Crystallization of allulose from supersaturated solutions

Abstract

The invention relates to a process for the crystallization of allulose comprising the steps of (a) providing a mother liquor comprising allulose having a temperature T0 within the range of from 20 to 60°C; an allulose purity p0 of at least 70 wt.-%; and a Brix value B0 of at least 75.0 °Bx; (b) crystallizing allulose from the mother liquor during a first time interval under substantially isothermal conditions until a pre- determined quantity q1 of allulose has been crystallized from the mother liquor; and (c) crystallizing allulose from the mother liquor during a second time interval following the first time interval, wherein at any time during the second time interval the temperature of the mother liquor is below T0.

Description

__________________________________________________________________________________ Crystallization of allulose from supersaturated solutions __________________________________________________________________________________

[0001] Priorities are claimed of European patent application no.24196897.3 that was filed on August 28, 2024, and of European patent application no.25151930.2 that was filed on January 15, 2025.

[0002] The invention relates to a process for the crystallization of allulose comprising the steps of (a) providing a mother liquor comprising allulose having a temperature T0 within the range of from 20 to 60°C; an allulose purity p0 of at least 70 wt.-%; and a Brix value B0 of at least 75.0 °Bx; (b) crystallizing allulose from the mother liquor during a first time interval under substantially isothermal conditions until a predetermined quantity q1 of allulose has been crystallized from the mother liquor; and (c) crys- tallizing allulose from the mother liquor during a second time interval following the first time interval, wherein at any time during the second time interval the temperature of the mother liquor is below T0.

[0003] Allulose is a low calory sweetener and there is a demand for allulose is crystalline form.

[0004] Various methods for providing solid allulose and crystalline allulose are known from the prior art.

[0005] US 20110237790 A1 relates to a method of producing D-psicose crystals from a D-psicose solution by using supersaturation.

[0006] US 20170313734 A1 and US 20190177351 A1 relate to method for producing high purity D- psicose crystals having a purity of 98% (w / w) or more and a grain size of MA200 or more.

[0007] US 20190330253 A1 relates to a method for producing D-allulose crystals that allows for a continuous production process and ensures a high yield.

[0008] US 20200040023 A1 and US 20230295209 A1 relate to a method for producing allulose crys- tals from an allulose syrup using seed crystals.

[0009] US 20200196648 A1 relates to functional saccharides having specific crystallinity, a method for preparing thereof, and a functional sweetener comprising the crystalline saccharides.

[0010] US 20200407389 A1 and US 20220315618 A1 relate to a method for preparing a crystalline functional sweetener, and more specifically, relates to a method for preparing a crystalline functional sweetener for raising the crystallization yield and increasing the particle size by controlling the content of impurities or production of impurities comprised in a solution for preparing the crystal.

[0011] US 20220162715 A1 relates to a process for drying allulose crystals.

[0012] US 20220332745 A1 relates to a preparation method for a D-psicose crystal containing 98% (w / w) or more D-psicose and 0.05% (w / w) or less ethanol based on 100% (w / w) of the entire crystal.

[0013] US 20230139835 A1 relates to a crystalline allulose with a defined particle size distribution, to a process for the production thereof, as well as to the use thereof.

[0014] US 20230159579 A1 relates to a process for the preparation of a solid allulose material com- prising crystalline allulose.

[0015] US 2023 0279037 A1 relates to a D-psicose crystal and a preparation method thereof. The method comprises: adding a seed crystal to a D-psicose solution and stirring uniformly, subjecting the solution to crystallization by gradient cooling and constant-temperature crystallization alternately at 50- 30°C, stopping the crystallization until the temperature of the solution is 30°C, separating the crystal by centrifugation, washing and drying, to obtain a D-psicose crystal.

[0016] US 20230287026 A1 relates to a method for preparing crystalline D-psicose by means of com- bining an evaporative crystallization method and a cooling crystallization method.

[0017] US 20230312631 A1 relates to an extrusion process for the preparation of a solid allulose com- position.

[0018] CN 110872332 B relates to a crystallization process of psicose. The crystallization process comprises the following steps: (1) carrying out primary crystallization by utilizing evaporative crystal- lization equipment, and (2) carrying out deep crystallization by utilizing cooling crystallization equip- ment. The process is divided into two steps of crystallization and comprises primary crystallization car- ried out by utilizing the evaporative crystallization equipment and deep crystallization carried out by utilizing the cooling crystallization equipment, so that the psicose crystal with a relatively large crystal size can be obtained, and an organic solvent is not used.

[0019] However, the known methods for providing crystalline allulose and the properties of the thus provided allulose are not satisfactory in every respect and there is a demand for improvements. It would be desirable to crystallize allulose from mother liquors within relatively short periods of time providing crystalline allulose with a high yield and a comparatively narrow particle size distribution. Crystalliza- tion should proceed in an economic manner and should allow for the preparation of crystalline allulose on an industrial scale.

[0020] It is an object of the invention to provide a process for the crystallization of allulose that has advantages over the processes of the prior art. It is a further object of the invention to provide crystalline allulose having advantages over the crystalline allulose of the prior art. SUMMARY OF THE INVENTION

[0021] This object has been achieved by the subject-matter of the patent claims.

[0022] It has been surprisingly found that allulose can be advantageously crystallized from aqueous solutions (mother liquors) in a two stage process comprising- an initial isothermal crystallization stage (first time interval) which can be performed under constant crystallization conditions, i.e. which does not necessarily require control, until a certain quantity of crystallized allulose has been obtained; and - a subsequent cooling crystallization stage (second time interval) where supersaturation of allulose is preferably closely monitored and kept within an advantageous range of the supersaturation ratio by controlling the temperature of the mother liquor in the course of cooling crystallization until a further quantity of crystallized allulose has been obtained, preferably by closed-loop controlling said tem- perature.

[0023] Further, it has been surprisingly found that the crystallized allulose that is obtained by the pro- cess according to the invention has a unique crystal habit that is characterized by certain x-ray reflections having certain intensity.

[0024] The two stage process according to the invention allows for crystallizing a significant quantity of allulose during the initial isothermal crystallization stage (first time interval) with good crystal prop- erties, especially a comparatively narrow particle size distribution, within a comparatively short period of time (first time interval). It has been found that secondary nucleation, which would be detrimental to the particle size distribution, can be suppressed during the initial isothermal crystallization stage such that a high yield of crystalline allulose can be obtained in an economic manner, especially within a short period of time (first time interval).

[0025] Secondary nucleation typically depends upon many factors including but not limited to stirrer geometry, stirring speed, type / shape of crystallizer, supersaturation, crystal size, crystal shape, weight fraction of crystal in the course of crystallization, solubility, purity of the liquid phase.

[0026] Further, the two stage process according to the invention allows for carefully adjusting crystal- lization conditions when it becomes relevant, namely during the subsequent cooling crystallization stage when secondary nucleation can be an issue that needs to be avoided or suppressed by keeping the system under appropriate crystallization conditions, especially within a certain range of the supersaturation ratio by controlling the temperature of the mother liquor, preferably by closed-loop controlling said temper- ature.

[0027] Therefore, the two stage process according to the invention likewise allows for crystallizing a significant quantity of allulose during the subsequent cooling crystallization stage with good crystal properties, especially a comparatively narrow particle size distribution, within a comparatively short period of time (second time interval). It has been found that secondary nucleation, which would be detrimental to the particle size distribution, can be suppressed during the subsequent cooling crystalli- zation stage by carefully adjusting supersaturation ratio, preferably within the range of from about 1.040 to about 1.065.

[0028] On the one hand, experimental data demonstrate that at lower supersaturation ratios, e.g., at about 1.035, crystallization is significantly slower. A direct comparison other otherwise identicalconditions revealed that compared to a supersaturation ratio of 1.050, crystallization at a supersaturation ratio of 1.035 is prolonged by about 43%. On the other hand, experimental data demonstrate that at higher supersaturation ratios, e.g., at about 1.070, the content of fine particles increases dramatically, likely due to secondary nucleation.

[0029] For example, it could be shown in experiments in accordance with the invention that at a super- saturation ratio of 1.050 (during the second stage, cooling crystallization) and at an initial allulose purity p0 of 92%, no detectable secondary nucleation occurred.

[0030] Still further, it has been surprisingly found that purity of allulose in the mother liquor has an impact on solubility of allulose and that this information can be advantageously used to effectively crys- tallize allulose. Purity of allulose decreases over time, because in the course of crystallization, allulose is continuously withdrawn from the liquid phase (mother liquor). Impurities that have been present from the very beginning in the mother liquor provided in step (a), e.g. fructose and / or glucose, remain in the mother liquor and due to the continuous withdrawal of allulose by crystallization and precipitation, the content of remaining impurities in the liquid phase (mother liquor) is relatively enriched over time.

[0031] Knowledge of the purity of allulose p(t) is necessary in order to correctly quantify the supersat- uration ratio. Preferably, the purity p(t) is not measured directly (e.g. sampling and HPLC analysis), but determined on the basis of the established mass balance, which is one of the great advantages of the process according to the invention.

[0032] It has been surprisingly found that particularly good results can be achieved when the mother liquor that is used as starting material for the isothermal crystallization stage (first time interval) has a maximal content of impurities. In this regard, a distinction is made between fructose as impurity on the one hand, and any impurity other than fructose on the other hand. It appears that impurities other than fructose inhibit crystallization of allulose. Preferably, the individual content of each individual impurity other than fructose is independently at most 10,000 ppmw (i.e. 1.0 wt.-%), preferably at most 9,000 ppmw, more preferably at most 8,000 ppmw, still more preferably at most 7,000 ppmw, yet more pref- erably at most 6,000 ppmw, even more preferably at most 5,000 ppmw, most preferably at most 4,000 ppmw, and in particular at most 3,000 ppmw.

[0033] The content of impurities other than fructose can be controlled by conventional measures, pref- erably by simulated moving bed (SMB) chromatography.

[0034] Furthermore, it has been surprisingly found that the content of impurities other than fructose can be controlled by adjusting the pH value of the raw syrup from which the mother liquor that is used as starting material for the isothermal crystallization stage (first time interval) is obtained, preferably by evaporation. It has been surprisingly found that formation of impurities which inhibits or slows down the crystallization can be reduced or even completely suppressed when the raw syrup prior to evapora- tion has a pH value within the range from about pH 4.0 to about pH 7.0.

[0035] The amount of precipitated crystalline allulose is preferably not measured directly (e.g. sam- pling, centrifugation and weight measurement), but instead determined via the decrease in the Brix value. The corresponding measurement signal B(t) can be converted directly into the amount of precip- itated crystalline allulose at time t, which is another one of the great advantages of the process according to the invention.

[0036] It is particularly advantageous when the Brix value B(t) is continuously measured online. The corresponding measurement signal B(t) is a parameter that is particularly suitable for controlling the process, especially the supersaturation ratio. During the initial cooling crystallization stage, the meas- urement signal B(t) is important to determine when the first time interval should be terminated. During the subsequent cooling crystallization stage (second time interval), the measurement signal B(t) is im- portant for control and regulation. In particular, the supersaturation ratio may be controlled and adjusted to stay within the desired range by regulating the temperature of the mother liquor according to the measurement signal B(t).

[0037] As the quantity of crystalline allulose can be monitored, the content of remaining impurities in the liquid phase (mother liquor) can be determined at any point in time of the process. The quantity of crystalline allulose can be measured directly. Preferably, the quantity of crystalline allulose is monitored indirectly based upon the Brix value (B(t)). It has been found that when the purity of allulose in the mother liquor at the start of the process (p0) is known, at any point in time t the quantity of crystalline allulose can be determined on the basis of the Brix value of the mother liquor measured at this point in time t, i.e. B(t). As allulose crystallizes and precipitates, the refractive index of the mother liquor changes. Likewise, the purity of allulose in the mother liquor at this point in time t, i.e. p(t), can be determined on the basis of the Brix value of the mother liquor measured at this point in time t, i.e. B(t), in knowledge of the purity of allulose in the mother liquor at the start of the process (p0).

[0038] Accordingly, as the corresponding purity of allulose may be determined from the content of impurities at any point in time, this information may be used in order to maintain proper supersaturation within the optimal range for the given purity of allulose. The lower the purity of allulose in the mother liquor, the higher its solubility (see Figure 1 and Figure 2). Supersaturation of allulose is therefore a function of purity of allulose in the mother liquor. Besides concentration of dry substance in the mother liquor (preferably in terms of Brix value), purity of allulose is additionally determined and used for controlling crystallization.

[0039] This is particularly relevant for the second stage, i.e. subsequent cooling crystallization. It is an essential advantage of the process according to the invention compared to known processes for crystal- lizing allulose that supersaturation can be controlled and kept within an optimized range taking into account the dry substance content of the mother liquor, preferably in terms of B(t), and additionally taking into account the momentarily given purity of allulose p(t). Both values can be derived from therefractive index; B(t) can be easily measured directly, and p(t) can be derived from B(t) in knowledge of p0.

[0040] Refractometry may be performed in accordance with ICUMSA Specification and Standard SPS- 3 (2000).

[0041] The process according to the invention provides excellent reproducibility with respect to particle size distribution (average particle size, coefficient of variation, aspect ratio) and space-time yield (mass of crystals per volume of liquid and time). In four independent experimental tests, the relative standard deviation of these parameters was below 6%.

[0042] Furthermore, even if the purity of allulose in the mother liquor at the start of the process (p0) is comparatively low, e.g. 90%, 80%, or even only 70%, the process according to the invention neverthe- less provides crystalline allulose with an excellent particle size distribution, especially with a low con- tent of fine particles, at high yield within reasonable periods of time. A purity of allulose in the mother liquor at the start of the process (p0) of below 98 wt.-% is particularly relevant because enzymatic pro- cesses for the conversion of fructose to allulose provide crude reaction products still containing exces- sive amounts of non-converted fructose and optionally other impurities. Purity of the thus obtained al- lulose can be significantly increased by work-up procedures involving e.g. simulated moving bed chro- matography and reverse osmosis. However, it can be laborious and inefficient from an economic per- spective to operate these work-up procedures under conditions providing allulose at very high purity, e.g. above 98 wt.-%. Thus, it is very advantageous when the subsequent crystallization process tolerates a certain amount of impurities, i.e. a lower purity of allulose in the mother liquor at the start of the process (p0). This significantly improves the overall efficiency of the process.

[0043] Moreover, it has been surprisingly found that at the end of the overall crystallization the viscos- ity of the suspension (magma) should preferably not exceed 20 Pa·s (determined in accordance with ICUMSA Specification and Standard SPS-5 (1994)).

[0044] Unexpectedly, additional advantages can be achieved when the energy that is entrained by agi- tation, e.g., stirring, is comparatively low. Best results have been achieved at energy dissipation rates of at most 1000 W·m-3, preferably at most 500 W·m-3.

[0045] The process according to the invention has economic advantages because high amounts of crys- talline allulose can be provided on large scale in short periods of time with high purity at low energy consumption and a high degree of crystallinity. As the crystalline allulose according to the invention can be prepared by the process according to the invention, the crystalline allulose likewise has the above advantages. Secondary nucleation can be suppressed and thus, the content of undesired fine corn is low, if any. Moreover, no or little crystal agglomerates are formed during crystallization, especially during crystal growth.

[0046] The crystalline allulose that is made available by the process according to the invention has unique crystal habit. It is characterized by a good average particle size with a narrow particle size dis- tribution and a good particle shape. The allulose crystals according to the invention have a good aspect ratio (b / l, breadth / length) so that needle crystals are avoided. The allulose crystals according to the in- vention have excellent processability as free flowing powders that can be advantageously used for pre- paring beverages and foodstuffs. After solid separation and drying, the allulose crystals that are obtained by crystallization can be commercialized as such. No grinding is needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 illustrates allulose saturation solubility in terms of dry substance content of allulose syrups having different purities as a function of temperature. The predominant impurity of the samples is fructose.

[0048] Figure 2 illustrates allulose saturation solubility in terms of Brix value of allulose syrups having different purities as a function of temperature. The predominant impurity of the samples is fructose.

[0049] Figure 3 illustrates space-time-yield (STY) as a function of the amount of allulose seed crystals. The average particle size of seeds amounted to 5.65 µm. Different quantities of seed crystals were used in relation to the quantity of allulose that was initially contained in the mother liquor.

[0050] Figures 4 and 5 illustrate Comparative Examples A1 and A2. Figures 6 to 9 illustrate Inventive Examples A3, A4, A5 and A6. In each case, Figure A shows photographs of the crystals, whereas Figure B shows a temperature time profile; Figures 6B, 7B, 8B and 9B additionally show the supersaturation time profiles.

[0051] Figure 10 illustrates Example B.

[0052] Figures 11, 12, 13 and 14 illustrate Example C.

[0053] Figure 15 and 16 illustrate preferred embodiments of the process according to the invention, as realized in Example D. DETAILED DESCRIPTION OF THE INVENTION

[0054] A first aspect of the invention relates to a process for the crystallization of allulose comprising the steps of (a) providing a mother liquor comprising allulose having - a temperature T0within the range of from 20 to 60°C; - an allulose purity p0of at least 70 wt.-%; and - a Brix value B0(temperature corrected, calibrated for sucrose) of at least 75.0 °Bx; (b) crystallizing allulose from the mother liquor during a first time interval under substantially isother- mal conditions until a predetermined quantity q1of allulose has been crystallized from the mother liquor; and(c) crystallizing allulose from the mother liquor during a second time interval following the first time interval, wherein at any time during the second time interval the temperature of the mother liquor is below T0.

[0055] The process according to the invention does typically not involve evaporation crystallization. Thus, in other words, the process according to the invention is preferably performed under atmospheric pressure.

[0056] For the purpose of the specification, "atmospheric pressure" is ambient air pressure, typically about 1013 hPa, which may vary depending upon altitude and weather conditions, e.g. from about 690 hPa to about 1070 hPa. For the purpose of the specification, "non-evaporative" means that no active measures are taken in order to alter, especially decrease the given atmospheric pressure, i.e. the given atmospheric pressure is preferably left unaltered (neither increased nor decreased).

[0057] Therefore, once the starting material (mother liquor) has been provided, the total volume of the mother liquor and the crystalline allulose remains essentially the same during the entire process. Water is not actively evaporated from the system. While it is contemplated that minor amounts of water may escape e.g. into the overhead atmosphere, crystallization of allulose does not rely upon increasing its concentration in the mother liquor by evaporating water, which would be the underlying principle of a conventional evaporation crystallization. As the process according to the invention does typically not involve evaporation crystallization but preferably only involves cooling crystallization, it requires less energy. This is because cooling requires less energy than evaporation so that the process according to the invention is advantageous also for economic reasons.

[0058] Avoiding evaporation crystallization has various advantages. Process control of non-evapora- tive crystallization is simpler, as only the crystal heat must be dissipated in order to keep the temperature constant.

[0059] In contrast, when crystallization is performed under evaporative conditions, the vacuum, the temperature and the addition of fresh feed solution must be controlled simultaneously in order to keep the temperature and the concentration constant. The following processes need to be considered for con- trol: (i) cooling of the solution by evaporation; (ii) change of vacuum, as evaporation creates pressure that can interfere with evaporation; (iii) heating of the solution by crystallization; (iv) concentration of the solution by evaporation of water; and (v) change of evaporation rate, as the addition of fresh feed solution, which only has a dry matter content of e.g.80 wt.-%, dilutes the mother liquor. This is much more complex than a non-evaporative isothermal crystallization in step (b) of the process according to the invention, which then only requires cooling to a temperature for seeding, addition of seeds, and dissipation of crystal heat.

[0060] The process according to the invention does not require any liquids other than water for crystal- lization, seeding and washing.

[0061] The process according to the invention can use various mother liquors as starting materials hav- ing a broad variety of different qualities. Different qualities may merely require different crystallization times, whereas all other parameters that are relevant for crystallization and that are to be adjusted may be adjusted in the same or analogous manner. Even when the mother liquors provided in step (a) have different qualities, the crystalline allulose products obtained by the process have comparable qualities. Particle size distribution and average particle size are nearly the same and no impurities can be detected in the crystals.

[0062] When seed crystals are used, the process according to the invention only requires low quantities of seed crystals which may be very small, e.g. DV50 of only about 5 µm.

[0063] The process according to the invention advantageously relies upon knowledge of - T0, p0 and B0 at the start of the process; - T(t), p(t) and B(t) at any point in time t during the process; and - solubility curves (calibration curves) that have been measured with mother liquors of known com- position, especially known allulose concentration and known allulose purity.

[0064] Based upon this information, it can be ensured, especially during cooling crystallization by adapting T(t), that the mother liquor is supersaturated within a desirable range of the supersaturation ratio. This can be achieved automatically based upon online measurements.

[0065] The process according to the invention allows for keeping supersaturation at a constant level during the cooling crystallization stage (step (c), second time interval), especially above a minimal threshold value, i.e. during the first isothermal crystallization stage and also during the subsequent cool- ing crystallization stage. This is particularly advantageous with respect to product quality and time. Secondary nucleation can thus be effectively avoided and crystalline product is obtained within short periods of time.

[0066] Compared to the crystallization processes of the prior art, the process according to the invention provides high yields within short periods of time. For example, when using seed magma a total yield of 52% crystalline allulose with excellent properties was obtained within 27.5 hours.

[0067] Allulose is also known as psicose. For the purpose of the specification, allulose is preferably present in form of D-allulose.

[0068] The process according to the invention comprises steps (a) through (c) that are preferably per- formed in consecutive alphabetical order. It is contemplated that additional measures may be taken be- fore step (a), during step (a), after step (a) and before step (b), during step (b), after step (b) and before step (c), during step (c) and / or after step (c).

[0069] For the purpose of the specification, a mother liquor is an aqueous solution of allulose from which allulose is crystallized. In the course of crystallization, allulose crystals are precipitated so that a suspension or slurry is formed consisting of a solid phase comprising allulose crystals and a liquid phasecomprising dissolved allulose. The liquid phase is referred to as mother liquor. The solid phase and the liquid phase may independently of one another contain additional substances such as carbohydrates (e.g. fructose and / or glucose) and other impurities. It is desirable that the majority of such additional sub- stances remain in solution of the mother liquor such that the solid phase consists of crystalline allulose, optionally amorphous allulose, and only minor amounts of such additional substances, if any.

[0070] Allulose purity refers to the content of allulose relative to the total dry solids content.

[0071] For the purpose of the specification, the Brix value (refractometric Brix) refers to the amount of allulose in the mother liquor and is the refractometric sucrose value of the mother liquor (juice, raw sugar solution). It is a unit of scale of a refractometer, which, through the index of refraction of light, expresses the concentration of dissolved solids in a sugar solution at 20°C. In other words, the Brix value is a calibration of the refractive index of a solution against dissolved sucrose. The Brix value is temperature corrected and calibrated for sucrose. Refractometers useful for measuring the Brix that au- tomatically provide temperature corrected values and that are calibrated for sucrose are commercially available e.g. Vaisala Polaris®PR23GP or PR53GP (Vaisala Oyi, Vantaa Finland); or VariRef (Schmidt Heansch GmbH & Co., Berlin, Germany).

[0072] In particularly preferred embodiments, the process according to the invention involves one or more of the following: (i) a raw syrup having a pH value within the range of from 4.5 to 7.0 is subjected to evaporation in order to provide the mother liquor in step (a); (ii) the initial purity p0 of allulose in the mother liquor provided in step (a) is greater than 70%, rela- tive to the total dry solids content of the mother liquor, preferably at most 98%; (iii) the individual content of each individual impurity other than fructose in the mother liquor pro- vided in step (a) is independently at most 1.0 wt.-%, relative to the total dry solids content of the mother liquor; (iv) the Brix value B at point in time t, i.e. B(t), is continuously measured, preferably by an online measurement; preferably, the supersaturation ratio of allulose is continuously derived from B(t); (v) during the cooling crystallization stage of step (c) (second time interval), the supersaturation ratio of allulose is kept within the range of from 1.040 to 1.065, preferably by adjusting the temperature of the mother liquor; (vi) the energy dissipation rate resulting from agitation, preferably stirring, during step (b) and / or step (c) is at most 1000 W·m-3, preferably at most 500 W·m-3; and / or (vii) at the end of the overall crystallization, the viscosity of the suspension (magma) does not exceed 20 Pa·s (determined in accordance with ICUMSA Specification and Standard SPS-5 (1994)). Step (a):

[0073] In step (a) of the process according to the invention, a mother liquor is provided which comprises allulose having- a temperature T0 within the range of from 20 to 60°C; - an allulose purity p0of at least 70 wt.-%; and - a Brix value B0(temperature corrected, calibrated for sucrose) of at least 75.0 °Bx.

[0074] The raw syrup that is preferably used as starting material for providing the mother liquor in step (a) can originate from various sources and may thus have different qualities. Allulose purity typically cannot be altered easily and is thus a parameter that is preferably accepted as it is given. Temperature and Brix value, however, can be altered - temperature can be adjusted to any desired value by means of a thermostat, whereas Brix value may adjusted by adding or evaporating water, respectively.

[0075] In preferred embodiments, the mother liquor originates from an enzymatic converter in which fructose was enzymatically converted to allulose and the conversion product was subsequently purified, preferably involving chromatography, and concentrated, preferably involving evaporation of water (for the purpose of the specification also referred to as "fresh mother liquor").

[0076] In other preferred embodiments, the mother liquor originates from the overhead solution that remains after solid liquid separation of crystallized allulose obtained by the process according to the invention and that is preferably subsequently concentrated, preferably involving evaporation of water. Preferably, such solid liquid separation is achieved by means of centrifugation (for the purpose of the specification also referred to as "centrifuge discharge").

[0077] In further preferred embodiments, the mother liquor originates from mixtures of fresh mother liquor with centrifuge discharge in any mixing ratio, preferably within the range from 90:10 to 10:90, more preferably 80:20 to 20:80, still more preferably 70:30 to 30:70, yet more preferably 65:35 to 35:65, even more preferably 60:40 to 40:60, most preferably 55:45 to 45:55, and in particular about 50:50 (v / v).

[0078] Step (a) preferably involves measuring allulose purity, Brix value and temperature of the raw syrup that is preferably used as starting material and subsequently adjusting these parameters to satisfy the above requirements, i.e. to fall within the above ranges.

[0079] Preferably, the mother liquor provided in step (a) is obtained by evaporating water from a raw syrup.

[0080] Preferably, the raw syrup from which the mother liquor provided in step (a) is preferably ob- tained by evaporation of water prior to evaporation has a pH value of at least 1.5, preferably at least 2.0, more preferably at least 2.5, still more preferably at least 3.0, yet more preferably at least 3.5, even more preferably at least 4.0, and most preferably at least 4.5.

[0081] Preferably, the raw syrup from which the mother liquor provided in step (a) is preferably ob- tained by evaporation of water prior to evaporation has a pH value of at least 4.6, preferably at least 4.8, more preferably at least 5.0, still more preferably at least 5.2, yet more preferably at least 5.4, even more preferably at least 5.6, and most preferably at least 5.8.

[0082] Preferably, the raw syrup from which the mother liquor provided in step (a) is preferably ob- tained by evaporation of water prior to evaporation has a pH value of at most 9.5, preferably at most 9.0, more preferably at most 8.5, still more preferably at most 8.0, yet more preferably at most 7.5, even more preferably at most 7.0, and most preferably at most 6.5.

[0083] Preferably, the raw syrup from which the mother liquor provided in step (a) is preferably ob- tained by evaporation of water prior to evaporation has a pH value within the range of from 3.0 to 9.0, preferably 3.5 to 8.5, more preferably 4.0 to 8.0, still more preferably 4.5 to 7.5, even more preferably 5.0 to 7.0, most preferably 5.5 to 6.5.

[0084] Experimental evidence indicates that below about pH 4.0 byproducts are formed in the course of concentrating an raw syrup from which the mother liquor provided in step (a) is preferably obtained by evaporating water. Said byproducts decelerate crystallization. Further, experimental evidence indi- cates that above about pH 7.0 the liquid phase discolors significantly, e.g. becomes brownish.

[0085] Step (a) preferably involves measuring pH value of the raw syrup from which the mother liquor provided in step (a) is preferably obtained and subsequently adjusting this parameter to satisfy the above requirements, i.e. to fall within the above ranges, e.g. by adding acid or base. The mother liquor provided in step (a) is preferably provided by evaporating water from the thus pH-adjusted raw syrup.

[0086] Preferably, the mother liquor provided in step (a) essentially consists of allulose, optionally fructose, optionally glucose, optionally inorganic salts, and optionally minor impurities.

[0087] Preferably, the allulose has been obtained by enzymatic conversion of fructose such that the fructose optionally contained in the mother liquor is preferably residual fructose that was not enzymat- ically converted and that was not quantitatively separated from allulose in subsequent work-up of the reaction product of the enzymatic conversion.

[0088] As the fructose in turn may either have been obtained from sucrose (invert sugar) or from glu- cose by enzymatic isomerization, the glucose optionally contained in the mother liquor is preferably residual glucose that was not quantitatively separated from allulose in subsequent work-up of the reac- tion product of the enzymatic conversion.

[0089] Inorganic salts may be contained in the mother liquor provided in step (a). Allulose has prefer- ably been purified by chromatography, preferably by simulated moving bed chromatography, and the composition preferably has been subjected to ion exchange. The content of residual amounts of inor- ganic salts at the given pH value results in an electric conductivity of the mother liquor provided in step (a), which is preferably at most 17.5 µS / cm, more preferably at most 15 µS / cm, still more preferably at most 12.5 µS / cm, yet more preferably at most 10 µS / cm, even more preferably at most 7.5 µS / cm, most preferably at most 5.0 µS / cm, and in particular at most 2.5 µS / cm,

[0090] Preferably, allulose, optionally present fructose, optionally present glucose and optionally pre- sent inorganic salts have a total content of at least 96.0 wt.-%, preferably at least 97.0 wt.-%, morepreferably at least 97.5 wt.-%, still more preferably at least 98.0 wt.-%, yet more preferably at least 98.5 wt.-%, even more preferably at least 99.0 wt.-%, most preferably at least 99.5 wt.-%, and in particular at least 99.8 wt.-%, of the total dry solids content of the mother liquor provided in step (a).

[0091] Preferably, the content of fructose is at most 22.5 wt.-%, preferably at most 20 wt.-%, more preferably at most 17.5 wt.-%, still more preferably at most 15 wt.-%, yet more preferably at most 12.5 wt.-%, even more preferably at most 10 wt.-%, most preferably at most 7.5 wt.-%, and in particular at most 5.0 wt.-% of the total dry solids content of the mother liquor provided in step (a).

[0092] Preferably, the content of fructose is at most 5.0 wt.-%, preferably at most 4.5 wt.-%, more preferably at most 4.0 wt.-%, still more preferably at most 3.5 wt.-%, yet more preferably at most 3.0 wt.-%, even more preferably at most 2.5 wt.-%, most preferably at most 2.0 wt.-%, and in particular at most 1.5 wt.-% of the total dry solids content of the mother liquor provided in step (a).

[0093] Preferably, the content of glucose is at most 3.5 wt.-%, preferably at most 3.0 wt.-%, more preferably at most 2.5 wt.-%, still more preferably at most 2.0 wt.-%, yet more preferably at most 1.5 wt.-%, even more preferably at most 1.0 wt.-%, most preferably at most 0.5 wt.-%, and in particular at most 0.1 wt.-% of the total dry solids content of the mother liquor provided in step (a).

[0094] Minor impurities that may be additionally contained in the mother liquor provided in step (a) may include but are not limited to chemical degradation products of allulose that are formed at elevated temperatures such as caramelization products, hydroxymethyl furfural (HMF), and the like. The total content of such impurities, however, is typically very low or even fully neglectable.

[0095] For the purpose of the specification, sucrose, fructose, and glucose are not to be considered as impurities.

[0096] Preferably, the mother liquor provided in step (a) has a total content of impurities of at most 3.0 wt.-%, preferably at most 2.5 wt.-%, more preferably at most 2.0 wt.-%, still more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, and even more preferably at most 0.8 wt.-% of the total dry solids content of the mother liquor provided in step (a). Preferably, the mother liquor provided in step (a) has a total content of impurities of at most 0.6 wt.-%, preferably at most 0.5 wt.-%, more preferably at most 0.4 wt.-%, still more preferably at most 0.3 wt.-%, yet more preferably at most 0.2 wt.-%, and even more preferably at most 0.1 wt.-% of the total dry solids content of the mother liquor provided in step (a).

[0097] Preferably, the mother liquor provided in step (a) has an individual content of each individual impurity other than fructose independently of at most 1.0 wt.-% of the total dry solids content of the mother liquor provided in step (a). In other words, any individual constituent of the mother liquor pro- vided in step (a) that is present besides allulose and optionally fructose has a maximal individual content of 1.0 wt.-%. Preferably, the mother liquor provided in step (a) has an individual content of each indi- vidual impurity other than fructose of independently at most 0.9 wt.-%, more preferably at most 0.8 wt.-%, still more preferably at most 0.7 wt.-%, yet more preferably at most 0.6 wt.-%, and even more pref- erably at most 0.5 wt.-% of the total dry solids content of the mother liquor provided in step (a). Prefer- ably, the mother liquor provided in step (a) has an individual content of each individual impurity other than fructose of independently at most 0.4 wt.-%, preferably at most 0.3 wt.-%, more preferably at most 0.2 wt.-%, still more preferably at most 0.1 wt.-%, yet more preferably at most 0.05 wt.-%, and even more preferably at most 0.01 wt.-% of the total dry solids content of the mother liquor provided in step (a).

[0098] Preferably, the impurities comprise allulose dimer, allulose-fructose disaccharide, allulose-glu- cose disaccharide, allulose tetramer, diallulose anhydride, levulinic acid, γ-hydroxy valeric acid (GVA), furfural, hydroxymethyl furfural (HMF), 2,5-dimethylfurane, 2,5-furane dicarboxylic acid (FDCA), 5- hydroxymethyl furane 2-carboxylic acid, 2,5-formyl furane carboxylic acid, 2,5-furane dialdehyde, 2,5- bis-(hydroxy-methyl)furane, bis(5-formyl-2-furfuryl)ether), furane-2-carboxylic acid, furane-3-carbox- ylic acid, 5-hydroxyfurfural, 2,5-dihydro-2,5-dimethoxyfurane, (2R)-5-oxotetrahydro-2-furane carbox- ylic acid, bis(5-methyl furfuryl)ether, 5,5ʹ-methylene-di(furane-2-carboxylic acid), or any combination thereof.

[0099] Preferably, the impurities comprise lactic acid, maltol, furaneol, allosone, glucosone, 1-desox- yglucosone, 3-desoxyglucosone, 3-desoxygalactosone, formic acid, acetic acid, propionic acid, glyoxal, or any combination thereof.

[0100] Preferably, the impurities comprise 2,3-butanedione, acetaldehyde, 2-keto-D-glucose (glu- cosone), 3-desoxyglucosone, or any combination thereof.

[0101] In particularly preferred embodiments, the impurities comprise 2,3-butanedione (diacetyl), i.e. CH3C(=O)C(C=O)CH3.

[0102] In particularly preferred embodiments, the impurities comprise acetaldehyde, i.e. CH3C(=O)H.

[0103] In particularly preferred embodiments, the impurities comprise 2-keto-D-glucose (glucosone), i.e..

[0104] In particularly preferred embodiments, the impurities comprise allosone, i.e..

[0105] In particularly preferred embodiments, the impurities comprise 3-desoxyglucosone, i.e..

[0106] Preferably, the mother liquor provided in step (a) has a content of hydroxymethyl furfural (HMF) within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor. Preferably, the mother liquor provided in step (a) has a content of hydroxymethyl furfural (HMF) of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

[0107] Preferably, the mother liquor provided in step (a) has a content of 2,3-butanedione within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor. Preferably, the mother liquor provided in step (a) has a content of 2,3-butanedione of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

[0108] Preferably, the mother liquor provided in step (a) has a content of acetaldehyde within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor. Preferably, the mother liquor provided in step (a) has a content of acetaldehyde of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

[0109] Preferably, the mother liquor provided in step (a) has a content of 2-keto-D-glucose within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor. Preferably, the mother liquor provided in step (a) has a content of 2-keto-D-glucose of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

[0110] Preferably, the mother liquor provided in step (a) has a content of allosone within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor. Preferably, the mother liquor provided in step (a) has a content of allosone of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

[0111] Preferably, the mother liquor provided in step (a) has a content of 3-desoxyglucosone within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor. Preferably, the mother liquor provided in step (a) has a content of 3-desoxyglucosone of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

[0112] Preferably, the mother liquor provided in step (a) is supersaturated; more preferably wherein the supersaturation ratio of allulose is at least 1.03, still more preferably within the range of from 1.03 to 1.15, yet more preferably 1.04 to 1.08.

[0113] Preferably, the supersaturation ratio of allulose in the mother liquor provided in step (a) is at least 1.035, more preferably at least 1.040, still more preferably at least 1.045, yet more preferably at least 1.050, even more preferably at least 1.055, most preferably at least 1.060, and in particular at least 1.065.

[0114] Preferably, the supersaturation ratio of allulose in the mother liquor provided in step (a) is at most 1.095, more preferably at most 1.090, still more preferably at most 1.085, yet more preferably at most 1.080, even more preferably at most 1.075, most preferably at most 1.070, and in particular at most 1.065.

[0115] It has been surprisingly found that supersaturation is a function of both, allulose concentration in terms of Brix value and allulose purity.

[0116] The phenomenon of supersaturation is known to the skilled person. Supersaturation typically occurs in a metastable zone of the temperature-concentration diagram. Supersaturation is defined as the difference between the actual and the equilibrium concentration: Δc = c - c*. The supersaturation ratio is c / c* > 1. The level of supersaturation determines the agglomeration, shape, and purity of the crystals. Crystal growth mainly occurs in the metastable zone where the concentration is higher than in saturation but below the concentration where spontaneous nucleation occurs. Primary nucleation takes place whenthe solution does not contain any crystals. Secondary nucleation is defined as the generation of nuclei with the presence of crystals.

[0117] The water solubility of allulose at 25°C is about 1 kg / L total volume (about 2.91 g / g water), whereas glucose dissolves at about 0.9 kg / L and fructose at about 1.1 kg / L (about 4 g / g water). As the content of allulose in the mother liquor provided in step (a) significantly exceeds the content of fructose and especially also the content of glucose, if any, it is reasonable to relate supersaturation to allulose, even if residual amounts of fructose and / or glucose are present.

[0118] Further, allulose, glucose and fructose have a very similar influence on refractive index. Thus, it is reasonable to relate the Brix value of the mother liquor to the total dry solids content. It is likewise reasonable to correlate the change of the Brix value of the mother liquor over time with the correspond- ing change of the allulose content in the mother liquor over time. The momentarily given purity of allulose p(t) can thus be derived from p0 based upon the momentarily measured value for B(t).

[0119] Solubility of allulose in presence of fructose (and optionally glucose) can be determined by routine experimentation (see Figure 1 and Figure 2).

[0120] Thus, the momentarily given supersaturation ratio may be derived from B(t) in knowledge of p0 and in knowledge of the dependence of allulose solubility on allulose purity p(t) (see Figure 1 and Figure 2).

[0121] For the purpose of the specification, supersaturation is related to the allulose that is present in the liquid phase, i.e. mother liquor.

[0122] For the purpose of the specification, the supersaturation ratio of the mother liquor is defined as the ratio of the concentration of allulose in solution under the given conditions divided by the solubility of allulose in solution under the given conditions, especially temperature and purity.

[0123] Preferably, the concentration of allulose in solution under the given conditions (i.e. the numer- ator of the supersaturation ratio) is determined on the basis of the refractive index of the mother liquor, preferably on the basis of the Brix value B(t). When the initial Brix value of the mother liquor provided in step (a), i.e. B0, and the initial purity of allulose in the mother liquor provided in step (a), i.e. p0, are known, the concentration of allulose in the mother liquor at any point in time t can be derived from B(t). The measured Brix value B(t) will typically be lower than the initial Brix value B0, and the difference B0- B(t) results from the amount of allulose that has been crystallized and precipitated from the begin- ning of the process (B0, p0) until the point in time t when B(t) is measured. Thus, the change of the concentration of allulose in solution is a function of and reflected by the change of the Brix value B(t) vs. B0.

[0124] Preferably, the solubility of allulose in solution under the given conditions (i.e. the denominator of the supersaturation ratio) is determined on the basis of B(t), p(t), p0, and solubility curves (calibration curves) that are measured by routine experimentation for known allulose solutions containing variousknown amounts of known impurities, especially fructose, at various known temperatures (see Figure 1 and Figure 2). However, p(t) is preferably not directly measured by derived from p0and the amount of allulose that has been crystallized and precipitated meanwhile, which amount can be derived from B(t) and B0. Thus, the change of the concentration of allulose in solution results in a change of the purity of allulose p(t) and is a function of and reflected by the change of the Brix value B(t) vs. B0 taking into account the initial purity of allulose p0. Once p(t) is known, the corresponding solubility of allulose in solution can be derived from the solubility curves (calibration curves).

[0125] The metastable zone can be determined for a given temperature by routine experiments. On the one hand, it can be determined at what concentration spontaneous nucleation occurs by concentrating a given allulose solution under reduced pressure at constant temperature. On the other hand, it can be determined at what concentration saturation is achieved by adding allulose crystals to a given allulose solution at constant temperature until the added allulose crystals are not dissolved any longer. When these measurements are performed at different temperatures, the temperature-concentration diagram may be plotted and the supersaturation ratio of a given allulose solution may be quantified.

[0126] For a given allulose solution, allulose concentration and supersaturation ratio, respectively, may be determined by different analytical methods. Preferably, the supersaturation ratio of allulose in the mother liquor provided in step (a) is determined by measuring refractive index or Brix value of the solution. Alternatively, the supersaturation ratio can be determined by means IR spectroscopy or Raman spectroscopy. Preferably, the supersaturation ratio of allulose in the mother liquor provided in step (a) is determined by measuring the Brix value.

[0127] Preferably, the supersaturation ratio of allulose in the mother liquor provided in step (a) is de- termined - by measuring allulose purity p0 of the mother liquor provided in step (a); - by measuring Brix value B0 of the mother liquor provided in step (a); - by measuring temperature T0of the mother liquor provided in step (a); - by determining allulose concentration in the mother liquor provided in step (a) from the measured values for p0and B0; and - by determining allulose solubility at the measured purity p0and at the measured temperature T0from calibration curves that have been measured with mother liquors of known allulose concentration and known allulose purity.

[0128] Preferably, the mother liquor provided in step (a) has a critical Brix value B0crwhich is defined by formula (1): ^^ 2^^^^^^ = 53.71 + 0.399 ∙ ^^^^ + 0.375 ∙ ^^^^ − 0.001551 ∙ ^^^^ − 0.003302 ∙ ^^2^^ + 0.001185 ∙ ^^^^ ∙ ^^^^(1) whereinT0 is the given temperature of the mother liquor in °C and p0is the given allulose purity of the mother liquor in percentage points; and wherein the ratio B0 / B0cris at least 1.03.

[0129] Preferably, the ratio B0 / B0cr is at least 1.04, preferably at least 1.05, more preferably at least 1.06, still more preferably at least 1.07, yet more preferably at least 1.08, even more preferably at least 1.09, most preferably at least 1.10, and in particular at least 1.11.

[0130] Preferably, the ratio B0 / B0cr is at most 1.13, preferably at most 1.12, more preferably at most 1.11, still more preferably at most 1.10, yet more preferably at most 1.09, even more preferably at most 1.08, most preferably at most 1.07, and in particular at most 1.06.

[0131] Preferably, the ratio B0 / B0cr is within the range of from 1.03 to 1.15, preferably 1.04 to 1.08.

[0132] Preferably, the temperature of the mother liquor T0 is set to a value that ensures supersaturation within the desired range.

[0133] In preferred embodiments, the optimal value for T0 is determined by formula (2) ^^ = −7.1 − 0.763 ∙^^^^ − 1.031 ∙ ^^ + 0.02166 ∙ (^^ 2 ^^ + 0.00821 ∙ ^^2^^^^^^) ^^^^(2) wherein B0 is the given Brix value of the mother liquor (starting material); p0 is the given allulose purity of the mother liquor (starting material); and G is a predetermined threshold value.

[0134] Preferably, the predetermined threshold value G is within the range of 1.03 to 1.15, preferably 1.04 to 1.08.

[0135] For example, when the value for B is 83.4 °Bx, when the value for p is 93 wt.-%, and when0 0 the predetermined threshold value G is 1.04, the optimal value for T can be calculated as follows:0 ^^ = −7.1 − 0.763 ∙− 1.031 ∙ 93 + 0.02166 ∙ (83.4 ^^1.04 1.04)+ 0.00821 ∙ 932 = 46.1°C.

[0136] In step (a) of the process according to the invention, a mother liquor may then be provided which comprises allulose having - a temperature T0of 46.1°C; - an allulose purity p0of 93 wt.-%; and - a Brix value B0of 83.4 °Bx.

[0137] During the initial isothermal crystallization in step (b) of the process according to the invention, the temperature is kept essentially constant. However, purity and Brix value decrease due to crystalliza- tion of allulose, because remaining impurities enrich in solution thereby leading to decreased purity of dissolved allulose, whereas crystallization and precipitation of allulose reduces the amount of dissolved allulose thereby leading to decreased Brix values. It has been surprisingly found that crystallization may be performed under isothermal conditions until a predetermined quantity of crystalline allulose has been obtained. Once this stage has been reached, however, the mode of crystallization should be changed in order to increase overall yield within minimized time periods without secondary nucleation.

[0138] During the subsequent cooling crystallization in step (c) of the process according to the inven- tion, the temperature is then adjusted, preferably by cooling. Preferably, the temperature of the mother liquor is adjusted as a function of one or more measured parameters, more preferably including p0 and / or B(t), still more preferably p0 and B(t). In the course of cooling crystallization, for any point in time t, the respective values for T(t), p(t) and B(t) can be determined, either directly by measurement or indi- rectly from the initial conditions and the current progress of crystallization (e.g. yield of crystalline allulose). Based upon this information, it can always be ensured that the system remains in the supersat- urated state within the desired range for the supersaturation ratio. During the cooling crystallization, the crystallization process can be controlled, preferably closed-loop controlled, preferably automatically by adjusting the temperature in order to specifically set how much above the solubility curve the concen- tration of allulose should be depending on its purity. If desirable, the value for the supersaturation ratio can be kept constant during isothermal crystallization and subsequent cooling crystallization. This al- lows to ensure crystal growth at all times.

[0139] Preferably, the controlled variable (reference variable) is the supersaturation and is regulated to a specific value. The manipulated variable is the reactor temperature. Preferably, the reactor temperature is also controlled (cascade control with external and internal control loop). The control of the supersat- uration results in a desired reactor temperature (manipulated variable from the outer control loop), which is controlled via the jacket temperature (manipulated variable from the inner control loop).

[0140] Preferably, T0is at least 20°C, preferably at least 21°C, more preferably at least 22°C, still more preferably at least 23°C, yet more preferably at least 24°C, even more preferably at least 25°C, most preferably at least 26°C, and in particular at least 27°C.

[0141] Preferably, T0is at least 28°C, preferably at least 29°C, more preferably at least 30°C, still more preferably at least 31°C, yet more preferably at least 32°C, even more preferably at least 33°C, most preferably at least 34°C, and in particular at least 35°C.

[0142] Preferably, T0is at most 55°C, preferably at most 54°C, more preferably at most 53°C, still more preferably at most 52°C, yet more preferably at most 51°C, even more preferably at most 50°C, most preferably at most 49°C, and in particular at most 48°C.

[0143] Preferably, T0is within the range of from 30 to 60°C.

[0144] Preferably, T0 is within the range of 30±10°C, preferably 30±9°C, more preferably 30±8°C, still more preferably 30±7°C, yet more preferably 30±6°C, even more preferably 30±5°C, most preferably 30±4°C, and in particular 30±3°C.

[0145] Preferably, T0 is within the range of 35±10°C, preferably 35±9°C, more preferably 35±8°C, still more preferably 35±7°C, yet more preferably 35±6°C, even more preferably 35±5°C, most preferably 35±4°C, and in particular 35±3°C.

[0146] Preferably, T0 is within the range of 40±10°C, preferably 40±9°C, more preferably 40±8°C, still more preferably 40±7°C, yet more preferably 40±6°C, even more preferably 40±5°C, most preferably 40±4°C, and in particular 40±3°C.

[0147] Preferably, T0 is within the range of 45±10°C, preferably 45±9°C, more preferably 45±8°C, still more preferably 45±7°C, yet more preferably 45±6°C, even more preferably 45±5°C, most preferably 45±4°C, and in particular 45±3°C.

[0148] Preferably, B0 is at least 75.2 °Bx, preferably at least 75.4 °Bx, more preferably at least 75.6 °Bx, and still more preferably at least 75.8 °Bx.

[0149] Preferably, B0 is at least 76.0 °Bx, preferably at least 76.2 °Bx, more preferably at least 76.4 °Bx, still more preferably at least 76.6 °Bx, yet more preferably at least 76.8 °Bx, even more preferably at least 77.0 °Bx, most preferably at least 77.2 °Bx, and in particular at least 77.4 °Bx.

[0150] Preferably, B0 is at least 77.6 °Bx, preferably at least 77.8 °Bx, more preferably at least 78.0 °Bx, still more preferably at least 78.2 °Bx, yet more preferably at least 78.4 °Bx, even more preferably at least 78.6 °Bx, most preferably at least 78.8 °Bx, and in particular at least 79.0 °Bx.

[0151] Preferably, B0 is at least 79.2 °Bx, preferably at least 79.4 °Bx, more preferably at least 79.6 °Bx, still more preferably at least 79.8 °Bx, yet more preferably at least 80.0 °Bx, even more preferably at least 80.2 °Bx, most preferably at least 80.4 °Bx, and in particular at least 80.6 °Bx.

[0152] Preferably, B0 is at least 80.8 °Bx, preferably at least 81.0 °Bx, more preferably at least 81.2 °Bx, still more preferably at least 81.4 °Bx, yet more preferably at least 81.6 °Bx, even more preferably at least 81.8 °Bx, most preferably at least 82.0 °Bx, and in particular at least 82.2 °Bx.

[0153] Preferably, B0is at least 82.4 °Bx, preferably at least 82.6 °Bx, more preferably at least 82.8 °Bx, still more preferably at least 83.0 °Bx, yet more preferably at least 83.2 °Bx, even more preferably at least 83.4 °Bx, most preferably at least 83.6 °Bx, and in particular at least 83.8 °Bx.

[0154] Preferably, B0is at least 84.0 °Bx, preferably at least 84.2 °Bx, more preferably at least 84.4 °Bx, still more preferably at least 84.6 °Bx, yet more preferably at least 84.8 °Bx, even more preferably at least 85.0 °Bx, most preferably at least 85.2 °Bx, and in particular at least 85.4 °Bx.

[0155] Preferably, B0 is at most 88.0 °Bx, preferably at most 87.8 °Bx, more preferably at most 87.6 °Bx, still more preferably at most 87.4 °Bx, yet more preferably at most 87.2 °Bx, even more preferably at most 87.0 °Bx, most preferably at most 86.8 °Bx, and in particular at most 86.6 °Bx.

[0156] Preferably, B0 is within the range of from 80.0 to 85.0 °Bx.

[0157] Preferably, the an allulose purity p0 of the mother liquor provided in step (a) is quantified.

[0158] Methods for determining allulose purity of a given solution are known to the skilled person and include e.g. HPLC analysis.

[0159] Preferably, p0 is at least 72.5 wt.-%, preferably at least 75.0 wt.-%, more preferably at least 77.5 wt.-%, still more preferably at least 80.0 wt.-%, yet more preferably at least 82.5 wt.-%, even more preferably at least 85.0 wt.-%, most preferably at least 87.5 wt.-%, and in particular at least 90.0 wt.-%, relative to the total dry solids content of the mother liquor.

[0160] Preferably, p0 is at most 99.0 wt.-%, preferably at most 98.0 wt.-%, more preferably at most 97.0 wt.-%, still more preferably at most 96.0 wt.-%, yet more preferably at most 95.0 wt.-%, even more preferably at most 94.0 wt.-%, most preferably at most 93.0 wt.-%, and in particular at most 92.0 wt.- %, relative to the total dry solids content of the mother liquor.

[0161] Preferably, p0 is within the range of from 80.0 to 100.0%.

[0162] Preferably, the mother liquor provided in step (a) has a pH value of at least 1.5, preferably at least 2.0, more preferably at least 2.5, still more preferably at least 3.0, yet more preferably at least 3.5, even more preferably at least 4.0, and most preferably at least 4.5.

[0163] Preferably, the mother liquor provided in step (a) has a pH value of at most 9.5, preferably at most 9.0, more preferably at most 8.5, still more preferably at most 8.0, yet more preferably at most 7.5, even more preferably at most 7.0, and most preferably at most 6.5.

[0164] Preferably, the mother liquor provided in step (a) has a pH value within the range of from 3.0 to 8.0, preferably 3.5 to 7.5, more preferably 4.0 to 7.0, still more preferably 4.5 to 6.5.

[0165] As already mentioned above, experimental evidence indicates that below about pH 4.0 byprod- ucts are formed in the course of concentrating a raw syrup that is used as starting material from which the mother liquor provided in step (a) is preferably obtained by evaporating water. Said byproducts decelerate crystallization. Further, experimental evidence indicates that above about pH 7.0 the liquid phase discolors significantly, e.g. becomes brownish.

[0166] Preferably, the mother liquor provided in step (a) has a density ρ0at 25.0°C within the range of from 1.37 to 1.47 kg / l. Densities ρ0at 25.0°C may thus amount to e.g. 1.38 kg / l, 1.39 kg / l, 1.40 kg / l, 1.41 kg / l, 1.42 kg / l, 1.43 kg / l, 1.44 kg / l, 1.45 kg / l, or 1.46 kg / l. Density ρ0may be determined in accord- ance with ICUMSA Specification and Standard SPS-4 (1998).

[0167] Preferably, the liquid phase of the mother liquor provided in step (a) has a viscosity η0 at 50.0°C within the range of from 0.040 to 5.000 Pa·s. Viscosities η0at 50.0°C may thus amount to e.g. 0.5 Pa·s,1.0 Pa·s, 1.5 Pa·s, 2.0 Pa·s, 2.5 Pa·s, 3.0 Pa·s, 3.5 Pa·s, 4.0 Pa·s, or 4.5 Pa·s. Viscosity η0may be determined in accordance with ICUMSA Specification and Standard SPS-5 (1994). Seeding

[0168] Preferably, the mother liquor provided in step (a) contains seed crystals of allulose.

[0169] Preferably, the seed crystals have been prepared by milling, preferably by air vortex milling, air jet milling, or pin milling.

[0170] Preferably, the content of the seed crystals is at least 0.01 ppmw, preferably at least 0.05 ppmw, more preferably at least 0.10 ppmw, still more preferably at least 0.15 ppmw, yet more preferably at least 0.20 ppmw, even more preferably at least 0.25 ppmw, most preferably at least 0.30 ppmw, and in particular at least 0.35 ppmw, relative to the allulose dry solids content of the mother liquor.

[0171] Preferably, the content of the seed crystals is at most 0.9 wt.-%, preferably at most 0.8 wt.-%, more preferably at most 0.7 wt.-%, still more preferably at most 0.6 wt.-%, yet more preferably at most 0.5 wt.-%, even more preferably at most 0.4 wt.-%, most preferably at most 0.3 wt.-%, and in particular at most 0.2 wt.-%, relative to the allulose dry solids content of the mother liquor.

[0172] It has been found that crystallization of allulose according to the process of the invention obeys the so-called d3-rule correlating weight and size of seed crystals with weight and size of product crystalswherein d50,p means size of product crystals [e.g. in µm] d50,s means size of seed crystals [e.g. in µm] mp means weight of product crystals [e.g. in kg] ms means weight of seed crystals [e.g. in kg].

[0173] This formula allows to determine, e.g., the amount of seed crystals of a given size that is needed in order to achieve at a desired yield (weight of product crystals) a certain size of product crystals. However, this rule is only valid when the number of crystals is not altered, i.e. when beyond seeding there is neither primary nucleation nor secondary nucleation.

[0174] The amount of seed crystals also affects space-time-yield. The more seed material, the higher the space-time-yield (see Figure 3).

[0175] Preferably, the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 of X µm, and wherein the content of the seed crystals is within the range of from (X·0.0114)3to (X·0.0116)3wt.-%, preferably (X·0.0113)3to (X·0.0117)3, more preferably (X·0.0112)3to (X·0.0118)3, still more preferably (X·0.0111)3to (X·0.0119)3, yet more preferably(X·0.0110)3to (X·0.0120)3, even more preferably (X·0.0109)3to (X·0.0121)3, most preferably (X·0.0108)3to (X·0.0122)3, and in particular (X·0.0107)3to (X·0.0123)3, relative to the allulose dry solids content of the mother liquor.

[0176] Preferably, the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 of at least 5 µm, preferably at least 10 µm, more preferably at least 15 µm, still more preferably at least 20 µm, yet more preferably at least 25 µm, even more preferably at least 30 µm, most preferably at least 35 µm, and in particular at least 40 µm.

[0177] Preferably, the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 of at most 85 µm, preferably at most 80 µm, more preferably at most 75 µm, still more preferably at most 70 µm, yet more preferably at most 65 µm, even more preferably at most 60 µm, most preferably at most 55 µm, and in particular at most 50 µm.

[0178] Preferably, the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 within the range of 20±18 µm, preferably 20±16 µm, more preferably 20±14 µm, still more preferably 20±12 µm, yet more preferably 20±10 µm, even more preferably 20±8 µm, most preferably 20±6 µm, and in particular 20±4 µm.

[0179] Preferably, the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 within the range of 30±18 µm, preferably 30±16 µm, more preferably 30±14 µm, still more preferably 30±12 µm, yet more preferably 30±10 µm, even more preferably 30±8 µm, most preferably 30±6 µm, and in particular 30±4 µm.

[0180] Preferably, the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 within the range of 40±18 µm, preferably 40±16 µm, more preferably 40±14 µm, still more preferably 40±12 µm, yet more preferably 40±10 µm, even more preferably 40±8 µm, most preferably 40±6 µm, and in particular 40±4 µm.

[0181] The seed crystals may be added as solids or suspensions / slurries. When the seed crystals are added as suspensions / slurries, the liquid phase preferably does not contain ethanol, preferably not any organic solvents.

[0182] In preferred embodiments, the seed crystals are added as suspensions / slurries that have been obtained by a previous crystallization process, preferably in accordance with the invention. Thus, seed- ing is preferably achieved by means of seed crystals suspended in mother liquor (i.e. seed magma, seed massecuite, crystal foot, footing, crystal base, heel, and the like).

[0183] Preferably, said seed crystals suspended in mother liquor are obtained from fresh mother liquor.

[0184] Although less preferred, it is contemplated that said seed crystals suspended in mother liquor may instead be obtained from centrifuge discharge. Under these circumstances, however, the discharge is preferably purified, preferably involving chromatography, and concentrated, preferably involving evaporation of water, before seed crystals are obtained therefrom.

[0185] In preferred embodiments, a portion of the composition that has been obtained in step (b) as a suspension / slurry is recycled to the process and used for seeding in step (a). Thus, seeding in step (a) is preferably achieved by means of seed crystals suspended in mother liquor (i.e. seed magma, seed mas- secuite, crystal foot, footing, crystal base, heel, and the like) that have been obtained in step (b).

[0186] In preferred embodiments, a portion of the composition that has been obtained in step (c) as a suspension / slurry is recycled to the process and used for seeding in step (a). Thus, seeding in step (a) is preferably achieved by means of seed crystals suspended in mother liquor (i.e. seed magma, seed mas- secuite, crystal foot, footing, crystal base, heel, and the like) that have been obtained in step (c).

[0187] Preferably, the process according to the invention does not involve ethanol, preferably not any organic solvents. Step (b):

[0188] In step (b) of the process according to the invention, allulose is crystallized from the mother liquor during a first time interval under substantially isothermal conditions until a predetermined quan- tity q1 of allulose has been crystallized from the mother liquor.

[0189] Preferably, step (b) is controlled, preferably with respect to temperature. Preferably, the temper- ature during step (b) (first time interval) is closed-loop controlled and kept essentially constant in order to maintain substantially isothermal conditions. A feed-back controlled loop is preferred, as crystalliza- tion enthalpy and entrained heat by stirring and / or agitation influence the temperature. Thus, in order to maintain the temperature at a constant level, active counter measures are typically necessary and these counter measures are preferably closed-loop controlled.

[0190] Step (b) of the process according to the invention is typically performed under non-evaporative conditions and at atmospheric pressure. Thus, step (b) of the process according to the invention is pref- erably performed under non-evaporative conditions.

[0191] Preferably, in step (b) the mother liquor is agitated, preferably by stirring. Preferably, stirring speed is optimized and the degree of supersaturation is adjusted accordingly. In preliminary tests, stir- ring speed is preferably minimized just avoiding sedimentation of crystals but still ensuring sufficient heat transfer. In subsequent tests, supersaturation of allulose is then increased until secondary nucleation is observed (threshold supersaturation). In the process according to the invention, supersaturation is then preferably adjusted to a value slightly below said threshold supersaturation. It has been found that sec- ondary nucleation of allulose highly depends upon stirring speed and likely also on stirrer geometry.

[0192] Preferably, the energy dissipation rate by stirring in step (b) is at most 800 W·m-3, preferably at most 700 W·m-3, more preferably at most 600 W·m-3, still more preferably at most 500 W·m-3, yet more preferably at most 400 W·m-3, even more preferably at most 300 W·m-3, most preferably at most 200 W·m-3, and in particular at most 100 W·m-3.

[0193] Preferably, the energy dissipation rate by stirring in step (b) is at most 90 W·m-3, preferably at most 80 W·m-3, more preferably at most 70 W·m-3, still more preferably at most 60 W·m-3, yet more preferably at most 50 W·m-3, even more preferably at most 40 W·m-3, most preferably at most 35 W·m-3, and in particular at most 30 W·m-3.

[0194] For the purpose of the specification, energy dissipation rate by stirring is preferably defined as the power dissipated by the impeller normalized by the fluid volume P / V, whereas a power number P0 is a characteristic impeller drag coefficient:

[0195] In the above formulas, ρ is the density (kg·m-3), N is the impeller speed (s-1), D is the impeller diameter (m), V is the fluid volume (m3), and P is the impeller power (J·s-1). Dynamic similarity is commonly compared using energy dissipation rate, or the amount of energy transferred from the impel- ler to the fluid. The energy dissipation rate can affect the growth rate of crystals by changing the size of the diffuse boundary layer and, correspondingly, the mass transfer rate of bulk solute to the crystal sur- face. A lack of dynamic similarity could be manifested through a change in the crystal habit or aspect ratios, manipulating the independent crystal face growth rates. Additionally, secondary nucleation may be promoted if the energy dissipation rate is not sufficient to maintain the crystal growth rate, causing the system to maintain or increase its level of supersaturation (see McKeown, R., Derdour, L., Dell'Orco, P. and Wertman, J. (2019). CRYSTALLIZATION DESIGN AND SCALE-UP. In Chemical Engineer- ing in the Pharmaceutical Industry (eds D.J. Ende and M.T. Ende), https: / / doi.org / 10.1002 / 9781119600800.ch24).

[0196] Preliminary experiments have shown that for optimal results, i.e. suppression of secondary nu- cleation, the average specific energy input over the entire crystallization period should be at most 50 W·m-3, preferably at most 45 W·m-3, more preferably at most 40 W·m-3, still more preferably at most 35 W·m-3, yet more preferably at most 30 W·m-3, even more preferably at most 25 W·m-3, most prefer- ably at most 20 W·m-3, but in particular greater than 0 W·m-3.

[0197] In preferred embodiments, step (b) is performed batchwise.

[0198] In other preferred embodiments, step (b) is performed semi-batchwise or continuously.

[0199] Preferably, at any time during the first time interval the temperature of the mother liquor is within the range of T0 ±3.0°C, preferably T0 ±2.7°C, more preferably T0 ±2.4°C, still more preferably T0 ±2.1°C, yet more preferably T0 ±1.8°C, even more preferably T0 ±1.5°C, most preferably T0 ±1.2°C, and in particular T0 ±0.9°C.

[0200] Preferably, step (b) involves determining the quantity of allulose that has been crystallized from the mother liquor at a time point within the first time interval.

[0201] Preferably, the quantity of allulose that has been crystallized is determined on the basis of re- fractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor; preferably Brix value.

[0202] Preferably, the quantity of allulose that has been crystallized is determined on the basis of the supersaturation ratio of the mother liquor. At the end of the first time interval the supersaturation ratio of the mother liquor is lower than it was at the beginning of the first time interval, i.e. in the mother liquor provided in step (a) at temperature T0. As the temperature during the first time interval is essen- tially kept constant (isothermal crystallization), during the first time interval the supersaturation ratio is essentially a function of B(t) and p(t). In preferred embodiments, this decrease of the supersaturation ratio in terms of the decrease of B(t) and the decrease of p(t) during the first time interval is taken as a measure for determining the end of the first time interval, i.e. predetermining the quantity of allulose q1 that has been crystalized.

[0203] Preferably, the quantity of allulose that has been crystallized is determined by weighing precip- itated solid.

[0204] Preferably, the predetermined quantity q1 of crystallized allulose is at least 7.5 wt.-%, preferably at least 10 wt.-%, more preferably at least 12.5 wt.-%, still more preferably at least 15 wt.-%, yet more preferably at least 17.5 wt.-%, even more preferably at least 20 wt.-%, most preferably at least 22.5 wt.- %, and in particular at least 25 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

[0205] Preferably, the predetermined quantity q1 of crystallized allulose is at most 35 wt.-%, preferably at most 32.5 wt.-%, more preferably at most 30 wt.-%, still more preferably at most 27.5 wt.-%, yet more preferably at most 25 wt.-%, even more preferably at most 22.5 wt.-%, most preferably at most 20 wt.-%, and in particular at most 17.5 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

[0206] Preferably, the predetermined quantity q1of crystallized allulose is within the range of 10 to 25 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

[0207] Preferably, at the end of the first time interval the mother liquor is supersaturated; more prefer- ably wherein the supersaturation ratio of allulose is within the range of from 1.01 to 1.07, still more preferably 1.02 to 1.06, yet more preferably 1.03 to 1.06.

[0208] Preferably, at the end of the first time interval, the supersaturation ratio of allulose is at least 1.025, more preferably at least 1.030, still more preferably at least 1.035, yet more preferably at least 1.040, even more preferably at least 1.045, most preferably at least 1.050, and in particular at least 1.055.

[0209] Preferably, at the end of the first time interval, the supersaturation ratio of allulose is at most 1.085, more preferably at most 1.080, still more preferably at most 1.075, yet more preferably at most 1.070, even more preferably at most 1.065, most preferably at most 1.060, and in particular at most 1.055.

[0210] Preferably, at any point in time during the first time interval of step (b), the mother liquor is supersaturated, i.e. the supersaturation ratio is at least 1.01.

[0211] Preferably, at any point in time during the first time interval of step (b), the supersaturation ratio of allulose is at least 1.025, more preferably at least 1.030, still more preferably at least 1.035, yet more preferably at least 1.040, even more preferably at least 1.045, most preferably at least 1.050, and in particular at least 1.055.

[0212] Preferably, at any point in time during the first time interval of step (b), the supersaturation ratio of allulose is at most 1.085, more preferably at most 1.080, still more preferably at most 1.075, yet more preferably at most 1.070, even more preferably at most 1.065, most preferably at most 1.060, and in particular at most 1.055.

[0213] At the end of the first time interval the supersaturation ratio of the mother liquor is lower than it was at the beginning of the first time interval, i.e. in the mother liquor provided in step (a) at temper- ature T0. Preferably, the relative difference of the supersaturation ratio at the beginning of the first time interval to the supersaturation ratio at the end of the first time interval is at least 0.01, preferably at least 0.02, more preferably at least 0.03, still more preferably at least 0.04, yet more preferably at least 0.05, even more preferably at least 0.06, most preferably at least 0.07, and in particular at least 0.08.

[0214] Preferably, supersaturation ratio of allulose is determined by measuring refractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor at the end of the first time interval; preferably Brix value.

[0215] Preferably, the supersaturation ratio of allulose in the mother liquor during the first time interval of step (b) is determined - in knowledge of initial allulose purity p0of the mother liquor provided in step (a); - in knowledge of initial Brix value B0of the mother liquor provided in step (a); - by measuring Brix value B(t) of the mother liquor during the first time interval of step (b); - by measuring temperature T(t) of the mother liquor during the first time interval of step (b); - by determining allulose purity p(t) in the mother liquor during the first time interval of step (b) from the measured values for p0, B0,and B(t); - by determining allulose concentration in the mother liquor during the first time interval of step (b) from the measured values for p0, B0, and B(t); and - by determining allulose solubility at the determined purity p(t) and at the measured temperature T(t) from calibration curves that have been measured with mother liquors of known allulose concentration and known allulose purity.

[0216] In the above context, "in knowledge" preferably means that the values of the parameters p0 and B0were previously determined or measured before step (b) was started, preferably measured; "measur- ing" preferably means that at point in time t the values of the parameters B(t) and T(t) are measured by a suitable methodology; and "determining" preferably means based upon known correlations, the values of the parameters p(t), allulose concentration and allulose solubility at the determined purity p(t) and at the measured temperature T(t) are derived from the known values of the parameters p0 and B0 and the measured values of the parameters B(t) and T(t). Suitable methodologies for measuring B(t) include measuring refractive index, Raman spectroscopy, infrared spectroscopy, and the like, preferably refrac- tive index. Suitable methodologies for measuring T(t) include direct temperature measurement with a thermometer.

[0217] Preferably, at the end of the first time interval the mother liquor has a Brix value B1 and a critical Brix value B1cr which is defined by formula (3): ^^^^^^^^ = 53.71 + 0.399 ∙ ^^^^ + 0.375 ∙ ^^ 2^^ − 0.001551 ∙ ^^^^ − 0.003302 ∙ ^^2^^ + 0.001185 ∙ ^^^^ ∙ ^^^^(3) wherein T1 is the given temperature of the mother liquor in °C, which essentially corresponds to T0, and p1 is the given allulose purity of the mother liquor in percentage points; and wherein the ratio B1 / B1cr is within the range of from 1.01 to 1.07, preferably 1.02 to 1.06, more prefer- ably 1.03 to 1.06.

[0218] Preferably, the given allulose purity p1 is defined by formula (4)wherein m0 is the total weight of the mother liquor provided in step (a) in kg, B0 is the Brix value of the mother liquor provided in step (a) in °Bx, p0 is the allulose purity of the mother liquor provided in step (a) in percentage points, and B1 is the Brix value of the mother liquor at the end of the first time interval in °Bx.

[0219] Preferably, the difference B0 / B0cr - B1 / B1cr is at least 0.005, preferably at least 0.010, more pref- erably at least 0.015.

[0220] Preferably, the difference B0 / B0cr- B1 / B1cris at most 0.07, preferably at most 0.06, more pref- erably at most 0.05.

[0221] Preferably, the first time interval lasts at least 5 hours, preferably at least 6 hours, more prefer- ably at least 7 hours, still more preferably at least 8 hours, yet more preferably at least 9 hours, even more preferably at least 10 hours, most preferably at least 12 hours, and in particular at least 15 hours.

[0222] Preferably, the first time interval lasts at most 60 hours, preferably at most 55 hours, more pref- erably at most 45 hours, still more preferably at most 40 hours, yet more preferably at most 35 hours, even more preferably at most 30 hours, most preferably at most 25 hours, and in particular at most 20 hours.

[0223] Preferably, the first time interval lasts at most 19 hours, preferably at most 18 hours, more pref- erably at most 17 hours, still more preferably at most 16 hours, yet more preferably at most 15 hours, even more preferably at most 14 hours, most preferably at most 13 hours, and in particular at most 12 hours.

[0224] Preferably, the first time interval lasts 10 to 60 hours.

[0225] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is below B0 (B1 < B0).

[0226] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is at least 75.2 °Bx, preferably at least 75.4 °Bx, more preferably at least 75.6 °Bx, and still more preferably at least 75.8 °Bx.

[0227] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is at least 76.0 °Bx, preferably at least 76.2 °Bx, more preferably at least 76.4 °Bx, still more preferably at least 76.6 °Bx, yet more preferably at least 76.8 °Bx, even more preferably at least 77.0 °Bx, most preferably at least 77.2 °Bx, and in particular at least 77.4 °Bx.

[0228] Preferably, at the end of the first time interval the Brix value of the mother liquor B1is at least 77.6 °Bx, preferably at least 77.8 °Bx, more preferably at least 78.0 °Bx, still more preferably at least 78.2 °Bx, yet more preferably at least 78.4 °Bx, even more preferably at least 78.6 °Bx, most preferably at least 78.8 °Bx, and in particular at least 79.0 °Bx.

[0229] Preferably, at the end of the first time interval the Brix value of the mother liquor B1is at least 79.2 °Bx, preferably at least 79.4 °Bx, more preferably at least 79.6 °Bx, still more preferably at least 79.8 °Bx, yet more preferably at least 80.0 °Bx, even more preferably at least 80.2 °Bx, most preferably at least 80.4 °Bx, and in particular at least 80.6 °Bx.

[0230] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is at least 80.8 °Bx, preferably at least 81.0 °Bx, more preferably at least 81.2 °Bx, still more preferably at least 81.4 °Bx, yet more preferably at least 81.6 °Bx, even more preferably at least 81.8 °Bx, most preferably at least 82.0 °Bx, and in particular at least 82.2 °Bx.

[0231] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is at least 82.4 °Bx, preferably at least 82.6 °Bx, more preferably at least 82.8 °Bx, still more preferably at least 83.0 °Bx, yet more preferably at least 83.2 °Bx, even more preferably at least 83.4 °Bx, most preferably at least 83.6 °Bx, and in particular at least 83.8 °Bx.

[0232] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is at least 84.0 °Bx, preferably at least 84.2 °Bx, more preferably at least 84.4 °Bx, still more preferably at least 84.6 °Bx, yet more preferably at least 84.8 °Bx, even more preferably at least 85.0 °Bx, most preferably at least 85.2 °Bx, and in particular at least 85.4 °Bx.

[0233] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is at most 88.0 °Bx, preferably at most 87.8 °Bx, more preferably at most 87.6 °Bx, still more preferably at most 87.4 °Bx, yet more preferably at most 87.2 °Bx, even more preferably at most 87.0 °Bx, most preferably at most 86.8 °Bx, and in particular at most 86.6 °Bx.

[0234] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is within the range of from 78.0 to 84.0 °Bx.

[0235] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is below B0 (B1 < B0), wherein the difference B0 - B1 is at least 0.1 °Bx, preferably is at least 0.2 °Bx, more preferably is at least 0.3 °Bx, still more preferably is at least 0.4 °Bx, yet more preferably is at least 0.5 °Bx, even more preferably is at least 0.6 °Bx, most preferably is at least 0.7 °Bx, and in particular is at least 0.8 °Bx.

[0236] Preferably, at the end of the first time interval the Brix value of the mother liquor B1 is below B0(B1< B0), wherein the difference B0- B1is at most 2.0 °Bx, preferably is at most 1.9 °Bx, more preferably is at most 1.8 °Bx, still more preferably is at most 1.7 °Bx, yet more preferably is at most 1.6 °Bx, even more preferably is at most 1.5 °Bx, most preferably is at most 1.4 °Bx, and in particular is at most 1.3 °Bx.

[0237] Preferably, at the end of the first time interval the allulose purity of the mother liquor p1is quantified. Methods for determining allulose purity of a given solution are known to the skilled person and include e.g. HPLC analysis.

[0238] In preferred embodiments, at the end of the first time interval the allulose purity of the mother liquor p1is quantified by analytical methods, preferably by HPLC.

[0239] In other preferred embodiments, at the end of the first time interval the allulose purity of the mother liquor p1is quantified on the basis of the allulose purity p0of the mother liquor provided in step(a) and on the basis of the predetermined quantity q1 of crystallized allulose. As by continuous crystal- lization of allulose from the mother liquor during step (b) (first time interval) allulose is continuously withdrawn from the mother liquor (solution, liquid phase) by crystallization and precipitation, the im- purities that were already contained from the very beginning in the mother liquor provided in step (a) are relatively enriched. Thus, as a consequence of enriched impurities, the allulose purity of the mother liquor p1 at the end of the first time interval is typically lower than the allulose purity p0 of the mother liquor provided in step (a). When the numerical values are known for p0 and q1, p1 may be calculated based upon the presumption that essentially no impurities are withdrawn together with allulose by crys- tallization. It has been confirmed by experimental tests and independent analysis that this presumption is applicable.

[0240] Alternatively, at the end of the first time interval the allulose purity of the mother liquor p1 is determined on the basis of m0, B0, p0 and B1 and formula (5):wherein m0is the total weight of the mother liquor provided in step (a) in kg, B0is the Brix value of the mother liquor provided in step (a) in °Bx, p0is the allulose purity of the mother liquor provided in step (a) in percentage points, and B1is the Brix value of the mother liquor at the end of the first time interval.

[0241] Preferably, at the end of the first time interval the allulose purity of the mother liquor p1is at least 72.5 wt.-%, preferably at least 75 wt.-%, more preferably at least 78.5 wt.-%, still more preferably at least 80 wt.-%, yet more preferably at least 82.5 wt.-%, even more preferably at least 85 wt.-%, most preferably at least 87.5 wt.-%, and in particular at least 90 wt.-%, relative to the total dry solids content of the mother liquor.

[0242] Preferably, at the end of the first time interval the allulose purity of the mother liquor p1 is at most 99.0 wt.-%, preferably at most 98.0 wt.-%, more preferably at most 97.0 wt.-%, still more prefer- ably at most 96.0 wt.-%, yet more preferably at most 95.0 wt.-%, even more preferably at most 94.0 wt.- %, most preferably at most 93.0 wt.-%, and in particular at most 92.0 wt.-%, relative to the total dry solids content of the mother liquor.

[0243] Preferably, at the end of the first time interval the allulose purity of the mother liquor p1 is within the range of from 80 to 100%, relative to the total dry solids content of the mother liquor.

[0244] Preferably, at the end of the first time interval the difference p0- p1is at least 0.05 wt.-%, pref- erably at least 0.1 wt.-%, more preferably at least 0.2 wt.-%, still more preferably at least 0.3 wt.-%, yet more preferably at least 0.4 wt.-%, even more preferably at least 0.5 wt.-%, most preferably at least 0.5 wt.-%, and in particular at least 0.7 wt.-%.

[0245] Preferably, step (b) involves measuring the temperature of the mother liquor at the time point t, i.e. T(t). Preferably, T(t) is measured continuously, preferably by an online measurement.

[0246] Preferably, step (b) involves measuring the Brix value of the mother liquor at the time point t, i.e. B(t). Preferably, B(t) is measured continuously, preferably by an online measurement. Step (c):

[0247] In step (c) of the process according to the invention, allulose is crystallized from the mother liquor during a second time interval following the first time interval, wherein at any time during the second time interval the temperature of the mother liquor is below T0.

[0248] Preferably, step (c) is closed-loop controlled. Preferably, the temperature during step (c) (second time interval) is actively adjusted as a function of one or more measured parameters. Preferably, adjust- ing the temperature is achieved by cooling. Preferably, the temperature of the mother liquor is adjusted as a function of one or more measured parameters, more preferably including p0 and / or B(t), still more preferably p0 and B(t).

[0249] Step (c) of the process according to the invention involves cooling crystallization.

[0250] The temperature of the mother liquor at the end of step (b), i.e. the isothermal crystallization stage, essentially corresponds to the temperature of the mother liquor provided in step (a), i.e. T0. In the course of step (c) - and if the process according to the invention involves additional steps beyond steps (a), (b) and (c), also in the course of such additional steps - the temperature of the mother liquor at any point in time t, i.e. T(t) does not exceed T0 (T(t) ≤ T0), preferably is below T0 (T(t) < T0). Thus, the process according to the invention preferably does not involve any heating except any heating that might be needed as counter measure for controlling the temperature during the cooling crystallization stage in order to properly adjust a certain temperature, preferably for closed-loop controlling said temperature. Preferably, in the course of step (c), T(t) is steadily decreased, i.e. may encompass intermittent phases where T(tm) = T(tn), but does not encompass any intermittent phases where T(tm) < T(tn), wherein tmis a first point in time during the second time interval of step (c) and tnis a second subsequent point in time during the second time interval of step (c).

[0251] Step (c) of the process according to the invention is typically performed under non-evaporative conditions and at atmospheric pressure. Thus, step (c) of the process according to the invention is pref- erably performed under non-evaporative conditions.

[0252] Preferably, in step (c) the mother liquor is agitated, preferably by stirring. Preferably, stirring speed is optimized and the degree of supersaturation is adjusted accordingly. In preliminary tests, stir- ring speed is preferably minimized just avoiding sedimentation of crystals but still ensuring sufficient heat transfer. In subsequent tests, supersaturation of allulose is then increased until secondary nucleation is observed (threshold supersaturation). In the process according to the invention, supersaturation is then preferably adjusted to a value slightly below said threshold supersaturation. It has been found that sec- ondary nucleation of allulose highly depends upon stirring speed and likely also on stirrer geometry.

[0253] Preferably, the energy dissipation rate by stirring in step (c) is at most 800 W·m-3, preferably at most 700 W·m-3, more preferably at most 600 W·m-3, still more preferably at most 500 W·m-3, yet more preferably at most 400 W·m-3, even more preferably at most 300 W·m-3, most preferably at most 200 W·m-3, and in particular at most 100 W·m-3.

[0254] Preferably, the energy dissipation rate by stirring in step (c) is at most 90 W·m-3, preferably at most 80 W·m-3, more preferably at most 70 W·m-3, still more preferably at most 60 W·m-3, yet more preferably at most 50 W·m-3, even more preferably at most 40 W·m-3, most preferably at most 35 W·m-3, and in particular at most 30 W·m-3.

[0255] Preferably, step (c) is performed batchwise.

[0256] Preferably, step (c) is performed batchwise or continuously.

[0257] In preferred embodiments, step (b) and step (c) of the process according to the invention are performed in the same crystallizer. Thus, under these circumstances, said crystallizer functions as iso- thermal crystallizer for step (b) and as cooling crystallizer for step (c). Suitable crystallizers are com- mercially available.

[0258] In other preferred embodiments, step (b) is performed in an isothermal crystallizer and step (c) is performed in a cooling crystallizer that is separate from the isothermal crystallizer. Suitable isothermal crystallizers and cooling crystallizers are commercially available.

[0259] Preferably, step (b) involves at the end of the first time interval transferring the suspension that is contained in the isothermal crystallizer into the cooling crystallizer.

[0260] Preferably, step (b) is performed in an isothermal crystallizer and step (c) is performed in a plurality of cooling crystallizers, preferably 2, 3, 4, 5 or more cooling crystallizers, that are separate from the isothermal crystallizer.

[0261] Preferably, step (b) involves at the end of the first time interval transferring the suspension that is contained in the isothermal crystallizer into the plurality of cooling crystallizers, preferably in equal fractions.

[0262] Figure 15 schematically illustrates a preferred embodiment of the process according to the in- vention which is performed in an isothermal crystallizer (1) and a separate cooling crystallizer (2).Figures 15A through C illustrate the time course of the process. Figure 15A illustrates step (a), wherein mother liquor (3) is provided in the isothermal crystallizer (1). Mother liquor (3) comprises allulose having a temperature T0, allulose purity p0and a Brix value B0. Figure 15B illustrates step (b), wherein within the isothermal crystallizer (1), isothermal crystallization during the first time interval yields allu- lose crystals (4) which are suspended in the remainder of mother liquor (3). Figure 15C illustrates step (c), wherein the product obtained in step (b) has been transferred into the cooling crystallizer (2). Within the cooling crystallizer, cooling crystallization during the second time interval increases the amount of allulose crystals (4) which are suspended in the remainder of mother liquor (3). In preferred embodi- ments, as shown, the product obtained in step (b) is completely transferred into a single cooling crystal- lizer. In other preferred embodiments, not shown, the product obtained in step (b) is divided into frac- tions that are separately transferred into a plurality of cooling crystallizers.

[0263] Preferably, step (c) involves mixing the product obtained in step (b), preferably the suspension, with another mother liquor.

[0264] Preferably, the another mother liquor originates from fresh mother liquor, centrifuge discharge or any mixture thereof; preferably a mixture of fresh mother liquor with centrifuge discharge in any mixing ratio, more preferably within the range from 90:10 to 10:90, more preferably 80:20 to 20:80, still more preferably 70:30 to 30:70, yet more preferably 65:35 to 35:65, even more preferably 60:40 to 40:60, most preferably 55:45 to 45:55, and in particular about 50:50 (v / v).

[0265] The another mother liquor is independent from the mother liquor provided in step (a).

[0266] The another mother liquor is independently characterized by a temperature T'0, an initial purity p'0, and a Brix value B'0.

[0267] For the purpose of the specification, all preferred embodiments of the mother liquor provided in step (a) likewise independently apply to the corresponding preferred embodiments of the another mother liquor.

[0268] The product obtained in step (b), i.e. at the end of the first time interval, is likewise characterized by temperature, purity and Brix value, namely by T1, p1, and B1.

[0269] Thus, when step (c) involves mixing the product obtained in step (b), preferably the suspension, with the another mother liquor, the temperature, purity and Brix value of the resultant mixture can be easily calculated from T'0and T1, from p'0and p1, and from B'0and B1, taking into account the volume and mass fraction of the another mother liquor and the product obtained in step (b), preferably the sus- pension.

[0270] For calculating the temperature of the resultant mixture (i.e., T1(mixture)) from T'0and T1, the mass and volume of the total suspension is relevant (liquid phase and solid phase altogether).

[0271] For calculating the purity of the resultant mixture (i.e., p1(mixture)) from p'0and p1, and likewise for calculating the Brix value of the resultant mixture (i.e., B1(mixture)) from B'0and B1, the mass andvolume of the liquid phase is relevant (ignoring the solid phase). The mass of the liquid phase can be calculated from the original mass of the mother liquor provided in step (a) (i.e. m0) minus the mass of the crystals at the end of step (b) (i.e. q1).

[0272] As the another mother liquid has no solid phase, the above distinction is only relevant for the product obtained in step (b).

[0273] The following equations are preferably used for calculating T1(mixture), p1(mixture), and B1(mixture):wherein m0 is the mass of the mother liquor provided in step (a) before mixing with the another mother liquor; T1is the temperature of the mother liquor at the end of step (b) before mixing with the another mother liquor; p1is the purity of the mother liquor at the end of step (b) before mixing with the another mother liquor; B1is the Brix value of the mother liquor at the end of step (b) before mixing with the another mother liquor; q1is the mass of crystals at the end of step (b) before mixing with the another mother liquor; m'0is the mass of the another mother liquor before mixing with the product obtained in step (b); T'0is the temperature of the another mother liquor before mixing with the product obtained in step (b); p'0is the purity of the another mother liquor before mixing with the product obtained in step (b); and B'0is the Brix value of the another mother liquor before mixing with the product obtained in step (b).

[0274] The thus calculated values for T1(mixture), p1(mixture), and B1(mixture)are then preferably used for T1, p1and B1in the same manner as for those embodiments of the process according to the invention wherein no another mother liquor is employed. Thus, all preferred embodiments according to the invention de- scribed on the basis of T1, p1and B1likewise analogously apply to such mixtures of product obtained in step (b) with another mother liquor, provided that the calculated values for T1(mixture), p1(mixture), and B1(mixture) are used for setting the values for T1, p1 and B1, respectively.

[0275] In preferred embodiments, the volume and / or mass of the product obtained in step (b), prefera- bly the suspension, is greater than the volume and / or mass of the another mother liquor.

[0276] In other preferred embodiments, the volume and / or mass of the another mother liquor is greater than the volume and / or mass of the product obtained in step (b), preferably the suspension.

[0277] When step (c) involves mixing the product obtained in step (b), preferably the suspension, the calculated results are then used for controlling and regulating step (c), instead of T1, p1, and B1.

[0278] Figure 16 schematically illustrates a preferred embodiment of the process according to the in- vention which is performed in an isothermal crystallizer (1) and a separate cooling crystallizer (2) and which involves mixing the product obtained in step (b) with another mother liquor. Figures 16A through C illustrate the time course of the process. Figure 16A illustrates step (a), wherein mother liquor (3) is provided in the isothermal crystallizer (1). Mother liquor (3) comprises allulose having a temperature T0, allulose purity p0 and a Brix value B0. Figure 16B illustrates step (b), wherein within the isothermal crystallizer (1), isothermal crystallization during the first time interval yields allulose crystals (4) which are suspended in the remainder of mother liquor (3). Another mother liquor (5) has been provided in the cooling crystallizer (2). Figure 16C illustrates step (c), wherein the product obtained in step (b) has been transferred into the cooling crystallizer (2) and mixed with the another mother liquor (5) provided therein. Within the cooling crystallizer, cooling crystallization during the second time interval increases the amount of allulose crystals (4) which are suspended in the remainder of the combination of mother liquor (3) and another mother liquor (5). It is contemplated that for mixing, the product obtained in step (b) may be added to the another mother liquor, or vice versa the another mother liquor may be added to the product obtained in step (b). In preferred embodiments, as shown, the product obtained in step (b) is completely transferred into a single cooling crystallizer. In other preferred embodiments, not shown, the product obtained in step (b) is divided into fractions that are separately transferred into a plurality of cooling crystallizers.

[0279] Upon mixing the another mother liquor with the product obtained in step (b) which already contains suspended crystalline allulose, the another mother liquor is seeded. Thus, seeding in step (c) is preferably achieved by means of seed crystals suspended in mother liquor (i.e. seed magma, seed mas- secuite, crystal foot, footing, crystal base, heel, and the like), namely by means of the product obtained in step (b).

[0280] Preferably, step (c) is performed until a predetermined quantity q2of allulose has been crystal- lized from the mother liquor.

[0281] Preferably, the quantity of allulose crystallized from the mother liquor during the second time interval is greater than the quantity of allulose crystallized from the mother liquor during the first time interval (q2- q1> q1).

[0282] Preferably, the predetermined quantity q2 of crystallized allulose is at least 25 wt.-%, preferably at least 27.5 wt.-%, more preferably at least 30 wt.-%, still more preferably at least 32.5 wt.-%, yet more preferably at least 35 wt.-%, even more preferably at least 37.5 wt.-%, most preferably at least 40 wt.- %, and in particular at least 42.5 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

[0283] Preferably, the predetermined quantity q2 of crystallized allulose is at most 67.5 wt.-%, prefer- ably at most 65 wt.-%, more preferably at most 62.5 wt.-%, still more preferably at most 60 wt.-%, yet more preferably at most 57.5 wt.-%, even more preferably at most 55 wt.-%, most preferably at most 52.5 wt.-%, and in particular at most 50 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

[0284] Preferably, the predetermined quantity q2 of crystallized allulose is within the range of 25 to 55 wt.-%, preferably 30 to 50 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

[0285] Preferably, the second time interval immediately follows the first time interval.

[0286] Preferably, the second time interval lasts at least 10 hours, preferably at least 12 hours, more preferably at least 14 hours, still more preferably at least 16 hours, yet more preferably at least 18 hours, even more preferably at least 20 hours, most preferably at least 22 hours, and in particular at least 24 hours.

[0287] Preferably, the second time interval lasts at most 80 hours, preferably at most 75 hours, more preferably at most 70 hours, still more preferably at most 65 hours, yet more preferably at most 60 hours, even more preferably at most 55 hours, most preferably at most 50 hours, and in particular at most 45 hours.

[0288] Preferably, the second time interval lasts at most at most 40 hours, preferably at most 35 hours, more preferably at most 30 hours, still more preferably at most 25 hours, yet more preferably at most 20 hours, even more preferably at most 15 hours, most preferably at most 12 hours, and in particular at most 10 hours.

[0289] Preferably, the second time interval lasts 10 to 80 hours.

[0290] Preferably, the second time interval is longer than the first time interval.

[0291] Preferably, the first time interval is longer than the second time interval.

[0292] Preferably, the second time interval immediately follows the first time interval, and wherein the first time interval and the second time interval together last at most 80 hours, preferably at most 75 hours, more preferably at most 70 hours, still more preferably at most 65 hours, yet more preferably at most 60 hours, even more preferably at most 55 hours, most preferably at most 50 hours, and in partic- ular at most 45 hours.

[0293] Preferably, the second time interval immediately follows the first time interval, and wherein the first time interval and the second time interval together last at most 40 hours, preferably at most 38 hours, more preferably at most 36 hours, still more preferably at most 34 hours, yet more preferably at most 32 hours, even more preferably at most 30 hours, most preferably at most 27.5 hours, and in par- ticular at most 25 hours.

[0294] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is below the Brix value of the mother liquor at the end of the first time interval B1 (B2 < B1).

[0295] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 68.0 °Bx, preferably at least 68.2 °Bx, more preferably at least 68.4 °Bx, still more preferably at least 68.6 °Bx, yet more preferably at least 68.8 °Bx, even more preferably at least 69.0 °Bx, most preferably at least 69.2 °Bx, and in particular at least 69.4 °Bx.

[0296] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 69.6 °Bx, preferably at least 69.8 °Bx, more preferably at least 70.0 °Bx, still more preferably at least 70.2 °Bx, yet more preferably at least 70.4 °Bx, even more preferably at least 70.6 °Bx, most preferably at least 70.8 °Bx, and in particular at least 71.0 °Bx.

[0297] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 71.2 °Bx, preferably at least 71.4 °Bx, more preferably at least 71.6 °Bx, still more preferably at least 71.8 °Bx, yet more preferably at least 72.0 °Bx, even more preferably at least 72.2 °Bx, most preferably at least 72.4 °Bx, and in particular at least 72.6 °Bx.

[0298] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 72.8 °Bx, preferably at least 73.0 °Bx, more preferably at least 73.2 °Bx, still more preferably at least 73.4 °Bx, yet more preferably at least 73.6 °Bx, even more preferably at least 73.8 °Bx, most preferably at least 74.0 °Bx, and in particular at least 74.2 °Bx.

[0299] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 74.4 °Bx, preferably at least 74.6 °Bx, more preferably at least 74.8 °Bx, still more preferably at least 75.0 °Bx, yet more preferably at least 75.2 °Bx, even more preferably at least 75.4 °Bx, most preferably at least 75.6 °Bx, and in particular at least 75.8 °Bx.

[0300] Preferably, at the end of the second time interval the Brix value of the mother liquor B2is at least 76.0 °Bx, preferably at least 76.2 °Bx, more preferably at least 76.4 °Bx, still more preferably at least 76.6 °Bx, yet more preferably at least 76.8 °Bx, even more preferably at least 77.0 °Bx, most preferably at least 77.2 °Bx, and in particular at least 77.4 °Bx.

[0301] Preferably, at the end of the second time interval the Brix value of the mother liquor B2is at least 77.6 °Bx, preferably at least 77.8 °Bx, more preferably at least 78.0 °Bx, still more preferably at least 78.2 °Bx, yet more preferably at least 78.4 °Bx, even more preferably at least 78.6 °Bx, most preferably at least 78.8 °Bx, and in particular at least 79.0 °Bx.

[0302] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 79.2 °Bx, preferably at least 79.4 °Bx, more preferably at least 79.6 °Bx, still more preferably at least 79.8 °Bx, yet more preferably at least 80.0 °Bx, even more preferably at least 80.2 °Bx, most preferably at least 80.4 °Bx, and in particular at least 80.6 °Bx.

[0303] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 80.8 °Bx, preferably at least 81.0 °Bx, more preferably at least 81.2 °Bx, still more preferably at least 81.4 °Bx, yet more preferably at least 81.6 °Bx, even more preferably at least 81.8 °Bx, most preferably at least 82.0 °Bx, and in particular at least 82.2 °Bx.

[0304] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 82.4 °Bx, preferably at least 82.6 °Bx, more preferably at least 82.8 °Bx, still more preferably at least 83.0 °Bx, yet more preferably at least 83.2 °Bx, even more preferably at least 83.4 °Bx, most preferably at least 83.6 °Bx, and in particular at least 83.8 °Bx.

[0305] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at least 84.0 °Bx, preferably at least 84.2 °Bx, more preferably at least 84.4 °Bx, still more preferably at least 84.6 °Bx, yet more preferably at least 84.8 °Bx, even more preferably at least 85.0 °Bx, most preferably at least 85.2 °Bx, and in particular at least 85.4 °Bx.

[0306] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is at most 88.0 °Bx, preferably at most 87.8 °Bx, more preferably at most 87.6 °Bx, still more preferably at most 87.4 °Bx, yet more preferably at most 87.2 °Bx, even more preferably at most 87.0 °Bx, most preferably at most 86.8 °Bx, and in particular at most 86.6 °Bx.

[0307] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is within the range of from 68.0 to 78.0 °Bx.

[0308] Preferably, at the end of the second time interval the Brix value of the mother liquor B2 is below the Brix value of the mother liquor at the end of the first time interval B1 (B2 < B1), wherein the difference B1- B2is at least 0.1 °Bx, preferably is at least 0.2 °Bx, more preferably is at least 0.3 °Bx, still more preferably is at least 0.4 °Bx, yet more preferably is at least 0.5 °Bx, even more preferably is at least 0.6 °Bx, most preferably is at least 0.7 °Bx, and in particular is at least 0.8 °Bx.

[0309] Preferably, at the end of the second time interval the Brix value of the mother liquor B2is below the Brix value of the mother liquor at the end of the first time interval B1(B2< B1), wherein the difference B1- B2is at most 2.0 °Bx, preferably is at most 1.9 °Bx, more preferably is at most 1.8 °Bx, still more preferably is at most 1.7 °Bx, yet more preferably is at most 1.6 °Bx, even more preferably is at most 1.5 °Bx, most preferably is at most 1.4 °Bx, and in particular is at most 1.3 °Bx.

[0310] Preferably, at the end of the second time interval the allulose purity of the mother liquor p2is at least 62.5 wt.-%, preferably at least 65 wt.-%, more preferably at least 67.5 wt.-%, still more preferably at least 70 wt.-%, yet more preferably at least 72.5 wt.-%, even more preferably at least 75 wt.-%, mostpreferably at least 77.5 wt.-%, and in particular at least 80 wt.-%, relative to the total dry solids content of the mother liquor.

[0311] Preferably, at the end of the second time interval the allulose purity of the mother liquor p2is at most 99.0 wt.-%, preferably at most 98.0 wt.-%, more preferably at most 97.0 wt.-%, still more prefer- ably at most 96.0 wt.-%, yet more preferably at most 95.0 wt.-%, even more preferably at most 94.0 wt.- %, most preferably at most 93.0 wt.-%, and in particular at most 92.0 wt.-%, relative to the total dry solids content of the mother liquor.

[0312] Preferably, at the end of the second time interval the allulose purity of the mother liquor p2 is within the range of from 70 to 100 wt.-%, relative to the total dry solids content of the mother liquor.

[0313] Preferably, at the end of the second time interval the difference p1 - p2 is at least 0.5 wt.-%, preferably at least 1.0 wt.-%, more preferably at least 1.5 wt.-%, still more preferably at least 2.0 wt.-%, yet more preferably at least 2.5 wt.-%, even more preferably at least 3.0 wt.-%, most preferably at least 3.5 wt.-%, and in particular at least 4.0 wt.-%.

[0314] Preferably, at the end of the second time interval the difference p0 - p2 is at least 4.5 wt.-%, preferably at least 5.0 wt.-%, more preferably at least 5.5 wt.-%, still more preferably at least 6.0 wt.-%, yet more preferably at least 6.5 wt.-%, even more preferably at least 7.0 wt.-%, most preferably at least 7.5 wt.-%, and in particular at least 8.0 wt.-%.

[0315] Preferably, step (c) involves determining the quantity of allulose that has been crystallized from the mother liquor at a time point t within the second time interval.

[0316] Preferably, the quantity of allulose that has been crystallized is determined on the basis of re- fractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor at the time point t, i.e. B(t); preferably Brix value.

[0317] Preferably, the quantity of allulose that has been crystallized is determined by weighing precip- itated solid.

[0318] Preferably, step (c) involves cooling the temperature of the mother liquor.

[0319] Preferably, cooling the temperature of the mother liquor is performed at a cooling rate with in the range of from 0.1 to 2.0°C / h.

[0320] Preferably, step (c) involves measuring the temperature of the mother liquor at the time point t, i.e. T(t). Preferably, T(t) is measured continuously, preferably by an online measurement.

[0321] Preferably, step (c) involves measuring the Brix value of the mother liquor at the time point t, i.e. B(t). Preferably, B(t) is measured continuously, preferably by an online measurement.

[0322] Preferably, step (c) involves determining the supersaturation ratio at the time point t. Preferably, the supersaturation ratio is determined continuously.

[0323] Preferably, step (c) involves measuring or determining allulose purity at the time point t, i.e. p(t). When p(t) is measured, p(t) is preferably measured continuously, preferably by an online meas- urement.

[0324] Preferably, step (c) involves controlling the temperature of the mother liquor, preferably closed- loop controlling said temperature.

[0325] Preferably, the temperature of the mother liquor is controlled automatically, preferably closed- loop controlled automatically.

[0326] Preferably, the temperature of the mother liquor is controlled, preferably closed-loop con- trolled, in dependence of - B(t), i.e. the Brix value of the mother liquor at the time point t in °Bx, and - p(t), i.e. the allulose purity in the mother liquor p(t) at a time point t.

[0327] Preferably, during the second time interval the temperature of the mother liquor is adjusted to maintain supersaturation ratio of allulose; more preferably wherein the supersaturation ratio of allulose is within the range of from 1.03 to 1.06, still more preferably 1.04 to 1.06.

[0328] Preferably, the temperature of the mother liquor is adjusted by cooling. Preferably, the temper- ature of the mother liquor is adjusted as a function of one or more measured parameters, more preferably including p0 and / or B(t), still more preferably p0 and B(t).

[0329] Preferably, at any point in time during the second time interval of step (c), the mother liquor is supersaturated, i.e. the supersaturation ratio is at least 1.01.

[0330] Preferably, at any point in time during the second time interval of step (c), the supersaturation ratio of allulose is at least 1.025, more preferably at least 1.030, still more preferably at least 1.035, yet more preferably at least 1.040, even more preferably at least 1.045, most preferably at least 1.050, and in particular at least 1.055.

[0331] Preferably, at any point in time during the second time interval of step (c), the supersaturation ratio of allulose is at most 1.085, more preferably at most 1.080, still more preferably at most 1.075, yet more preferably at most 1.070, even more preferably at most 1.065, most preferably at most 1.060, and in particular at most 1.055.

[0332] Preferably, the supersaturation ratio of allulose is determined by measuring refractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor; preferably Brix value.

[0333] Preferably, the supersaturation ratio of allulose in the mother liquor during the second time in- terval of step (c) is determined - in knowledge of initial allulose purity p0of the mother liquor provided in step (a); - in knowledge of initial Brix value B0of the mother liquor provided in step (a);- preferably in knowledge of allulose purity p1 of the mother liquor at the end of the first time interval in step (b); - preferably in knowledge of Brix value B1of the mother liquor at the end of the first time interval in step (b); - by measuring Brix value B(t) of the mother liquor during the second time interval of step (c); - by measuring temperature T(t) of the mother liquor during the second time interval of step (c); - by determining allulose purity p(t) in the mother liquor during the second time interval of step (c) from the measured values for p0, B0, and B(t); - by determining allulose concentration in the mother liquor during the second time interval of step (c) from the measured values for p0, B0, and B(t); and - by determining allulose solubility at the determined purity p(t) and at the measured temperature T(t) from calibration curves that have been measured with mother liquors of known allulose concentration and known allulose purity.

[0334] In the above context, "in knowledge" preferably means that the values of the parameters p0 and B0 were previously determined or measured before step (b) was started, preferably measured, and that preferably the values of the parameters p1 and B1 were previously determined or measured at the end of step (b) and before step (c) was started; "measuring" preferably means that at point in time t the values of the parameters B(t) and T(t) are measured by a suitable methodology; and "determining" preferably means that based upon known correlations, the values of the parameters p(t), allulose concentration and allulose solubility at the determined purity p(t) and at the measured temperature T(t) are derived from the known values of the parameters p0 and B0 and the measured values of the parameters B(t) and T(t). Suitable methodologies for measuring B(t) include measuring refractive index, Raman spectroscopy, infrared spectroscopy, and the like, preferably refractive index. Suitable methodologies for measuring T(t) include direct temperature measurement with a thermometer.

[0335] Preferably, step (c) involves determining the allulose purity in the mother liquor p(t) at a time point t within the second time interval.

[0336] It has been surprisingly found that allulose purity has an impact on allulose solubility and is thus an important parameter for supersaturation, especially in the course of step (c).

[0337] In preferred embodiments, allulose purity in the mother liquor p(t) at a time point t is determined by analysis, preferably by HPLC.

[0338] In other preferred embodiments, p(t) is defined by formula (6)wherein m0is the total weight of the mother liquor provided in step (a) in kg, B0is the Brix value of the mother liquor provided in step (a) in °Bx, p0is the allulose purity of the mother liquor provided in step (a) in percentage points, and B(t) is the Brix value of the mother liquor at the time point t in °Bx.

[0339] Preferably, step (c) involves the substeps (c1) determining the Brix value of the mother liquor B(t) at the time point t; (c2) determining a critical Brix value of the mother liquor B(t)crat the time point t which is defined by formula (7): ^^(^^) 2^^^^ = 53.71 + 0.399 ∙ ^^(^^) + 0.375 ∙ ^^(^^) − 0.001551 ∙ ^^(^^) − 0.003302 ∙ ^^(^^)2 + 0.001185 ∙ ^^(^^) ∙ ^^(^^)(7) wherein T(t) is the given temperature of the mother liquor at the time point t in °C; and p(t) is the given allulose purity of the mother liquor at the time point t in percentage points; (c3) determining the ratio B(t) / B(t)cr and comparing it with a predetermined threshold H value; when the ratio B(t) / B(t)cr deviates from the predetermined threshold H value: (c ) determining a target temperature of the mother liquor T , which is defined by formula (8)4 target ^^ = −7.1 − 0.763 ∙^^(^^) −1.031 ∙ ^^(^^) + 0.02166 ∙^^(^^) 2 ^^^^^^^^^^^^ ()+ 0.00821 ∙ ^^(^^)2^^ ^^ (8) wherein B(t) is the given Brix value of the mother liquor B(t) at the time point t; H is the predetermined threshold value; andp(t) is the given allulose purity of the mother liquor at the time point t; and (c5) adjusting the temperature of the mother liquor to Ttarget.

[0340] Preferably, the predetermined threshold value H is within the range of 1.03 to 1.06, preferably 1.04 to 1.06.

[0341] Preferably, in substep (c5) the temperature of the mother liquor is adjusted at a rate within the range of from ±0.1 to ±2.0°C / h.

[0342] As already mentioned above, when step (c) involves mixing the product obtained in step (b), preferably the suspension, with another mother liquor, the temperature, purity and Brix value of the resultant mixture can be easily calculated from T'0 and T1, from p'0 and p1, and from B'0 and B1, taking into account the volume and mass fraction of the another mother liquor and the product obtained in step (b), preferably the suspension.

[0343] Preferably, the temperature of the another mother liquor, i.e. T'0, is adjusted such that after mixing the product obtained in step (b) with the another mother liquor, the ratio B(t) / B(t)cr deviates from the predetermined threshold H by not more than ±0.005. The values for m0, T1, p1, B1, q1, m'0, and B'0 are known from corresponding measurements or can be derived from measurements by calculations, as described above.

[0344] When the ratio B(t) / B(t)cr is identical to the predetermined threshold H, cooling crystallization can be commenced and continued at the desired supersaturation. When the ratio B(t) / B(t)cr is close to the predetermined threshold H, the desired supersaturation can quickly be achieved. The temperature T'0 of the another mother liquor is preferably adjusted so that the temperature of the mixture of the product obtained in step (b) with the another mother liquor, i.e. T1(mixture), corresponds to the target temperature of the mother liquor, i.e. Ttarget, for controlling and regulating supersaturation.

[0345] In analogy to above formula (8), this means at the end of step (b): ^^^^^^^^^^^^^^= ^^^^(^^^^^^^^^^^^^^)=−7.1 − 0.763 ∙^^^^(^^^^^^^^^^^^^^)^^− 1.031 ∙ ^^^^(^^^^^^^^^^^^^^) + 0.02166^^ (^^^^^^ ) 2 ∙( ^^^^^^^^^^ )+ 0.00821 ∙ ^^ (^^^^^^^ )2^^^^ ^^^^^^^

[0346] T1(mixture) can be calculated from T1, m0, T'0and m'0: ′ ′ () (^^ ^^^^^^^ ^^^^ ∙ ^^^^ + ^^ ^^ ∙ ^^ ^^) ^^ ^^^^^^^ =(^^^^ + ^^′ ^^)

[0347] This equation can be resolved for T'0: ^^^ (^^^^^^^^^^^^^^) ∙ (^^ + ^^′) − (^^ ∙ ^^ )^^′=^ ^^ ^^ ^^ ^^^^^^′^^

[0348] Preferably, at the end of the second time interval the temperature of the mother liquor T2, wherein the difference T0- T2is at least 2.5°C, preferably at least 5.0°C, more preferably at least 7.5°C, still more preferably at least 10°C, yet more preferably at least 12.5°C, even more preferably at least 15°C, most preferably at least 17.5°C, and in particular at least 20°C.

[0349] Preferably, at the end of the second time interval the temperature of the mother liquor T2 is at least 3.0°C, preferably at least 4.0°C, more preferably at least 5.0°C, still more preferably at least 6.0°C, yet more preferably at least 7.0°C, even more preferably at least 8.0°C, most preferably at least 9.0°C, and in particular at least 10°C.

[0350] Preferably, at the end of the second time interval the temperature of the mother liquor T2 is at most 42°C, preferably at most 41°C, more preferably at most 40°C, still more preferably at most 39°C, yet more preferably at most 38°C, even more preferably at most 37°C, most preferably at most 36°C, and in particular at most 35°C.

[0351] Preferably, at the end of the second time interval the temperature of the mother liquor T2 is within the range of from 10 to 35°C.

[0352] In particularly preferred embodiments, the process according to the invention comprises the steps of (a) providing a mother liquor comprising allulose having a temperature T0 within the range of from 20 to 60°C; an allulose purity p0 of at least 70 wt.-%; and a Brix value B0 (temperature corrected, calibrated for sucrose) of at least 75.0 °Bx; wherein the mother liquor provided in step (a) is super- saturated; preferably wherein the supersaturation ratio of allulose is at least 1.03, more preferably within the range of from 1.03 to 1.15, still more preferably 1.04 to 1.08; (b) crystallizing allulose from the mother liquor during a first time interval under substantially isother- mal conditions until a predetermined quantity q1 of allulose has been crystallized from the mother liquor; wherein at the end of the first time interval the mother liquor is supersaturated; preferably wherein the supersaturation ratio of allulose is within the range of from 1.01 to 1.07, more prefer- ably 1.02 to 1.06, still more preferably 1.03 to 1.06; and (c) crystallizing allulose from the mother liquor during a second time interval following the first time interval, wherein at any time during the second time interval the temperature of the mother liquor is below T0, wherein step (c) involves controlling the temperature of the mother liquor, preferably closed-loop controlling said temperature, and wherein during the second time interval the temper- ature of the mother liquor is adjusted to maintain supersaturation ratio of allulose; preferably wherein the supersaturation ratio of allulose is within the range of from 1.03 to 1.06, more prefer- ably 1.04 to 1.06; preferably, the temperature of the mother liquor is adjusted by cooling; prefera- bly, the temperature of the mother liquor is adjusted as a function of one or more measured param- eters, more preferably including p0and / or B(t), still more preferably p0and B(t).

[0353] The process according to the invention advantageously controls the supersaturation ratio of al- lulose in order to provide optimized yield of crystalline allulose with optimized quality under economi- cally optimized conditions. As crystallization during step (b) (first time interval) is essentially isother- mal, the temperature of the mother liquor during step (b) (first time interval) essentially corresponds to T0. As crystallization during step (c) (second time interval) is performed as cooling crystallization, whereas lowering the temperature of the mother liquor is necessary in order to properly maintain and control the supersaturation ratio, the temperature of the mother liquor during step (c) (second time in- terval) is typically below T0. Preferred ranges for the supersaturation ratio during step (b) (first time interval) and (c) (second time interval) of the process according to the invention are compiled in the table here below as embodiments A1to A4and B1to B4: step (a) start of step (b) end of step (b) during step (c) A1> 1.06 1.03-1.06 1.03-1.06 2 A ≥ 1.07 1.03-1.06 1.03-1.06 A3≥ 1.08 1.03-1.06 1.03-1.06 A4≥ 1.09 1.03-1.06 1.03-1.06 B1> 1.06 1.04-1.06 1.04-1.06 B2≥ 1.07 1.04-1.06 1.04-1.06 B3≥ 1.08 1.04-1.06 1.04-1.06 B4≥ 1.09 1.04-1.06 1.04-1.06

[0354] In further particularly preferred embodiments, the process according to the invention comprises the steps of (a) providing a mother liquor comprising allulose having a temperature T within the range of from 200 to 60°C; an allulose purity p0 of at least 70 wt.-%; and a Brix value B0 (temperature corrected, calibrated for sucrose) of at least 75.0 °Bx; wherein the mother liquor provided in step (a) has a critical Brix value B which is defined by formula (1):0cr ^^ = 53.71 + 0.399 ∙ ^^ + 0.375 ∙ ^^ − 0.001551 ∙ ^^2 − 0.003302 ∙ ^^2^^^^^^ ^^ ^^ ^^ ^ + 0.001185 ∙ ^^^^ ∙ ^^^^^(1) wherein T is the given temperature of the mother liquor in °C and p is the given allulose purity0 0 of the mother liquor in percentage points; and wherein the ratio B / B is at least 1.03, preferably0 0cr within the range of from 1.03 to 1.15, more preferably 1.04 to 1.08; (b) crystallizing allulose from the mother liquor during a first time interval under substantially isother- mal conditions until a predetermined quantity q of allulose has been crystallized from the mother1 liquor; wherein at the end of the first time interval the mother liquor has a Brix value B and a1 critical Brix value B1crwhich is defined by formula (3): 22 ^^ = 53.71 + 0.399 ∙ ^^ + 0.375 ∙ ^^ − 0.001551 ∙ ^^ − 0.003302 ∙ ^^ + 0.001185 ∙ ∙^^ ^^^^(3)wherein T1 is the given temperature of the mother liquor in °C, which essentially corresponds to T0, and p1is the given allulose purity of the mother liquor in percentage points; and wherein the ratio B1 / B1cris within the range of from 1.01 to 1.07, preferably 1.02 to 1.06, more preferably 1.03 to 1.06; preferably wherein the given allulose purity p1 is defined by formula (4)wherein m0is the total weight of the mother liquor provided in step (a) in kg, B0is the Brix value of the mother liquor provided in step (a) in °Bx, p0is the allulose purity of the mother liquor pro- vided in step (a) in percentage points, and B1is the Brix value of the mother liquor at the end of the first time interval in °Bx; and (c) crystallizing allulose from the mother liquor during a second time interval following the first time interval, wherein at any time during the second time interval the temperature of the mother liquor is below T0, wherein step (c) involves controlling the temperature of the mother liquor, preferably closed-loop controlling said temperature; wherein step (c) involves determining the allulose purity in the mother liquor p(t) at a time point t within the second time interval; wherein p(t) is defined by formula (6)wherein m0 is the total weight of the mother liquor provided in step (a) in kg, B0 is the Brix value of the mother liquor provided in step (a) in °Bx, p0 is the allulose purity of the mother liquor pro- vided in step (a) in percentage points, and B(t) is the Brix value of the mother liquor at the time point t in °Bx; wherein step (c) involves the substeps(c1) determining the Brix value of the mother liquor B(t) at the time point t; (c2) determining a critical Brix value of the mother liquor B(t)crat the time point t which is defined by formula (7): ^^(^^) = 53.71 + 0.399 ∙ ^^(^^) + 0.375 ∙ ^^(^^) − 0.001551 ∙ ^^(^^)2 − 0.003302 ∙ ^^(^^)2^^^^ + 0.001185 ∙ ^^(^^) ∙ ^^(^^)(7) wherein T(t) is the given temperature of the mother liquor at the time point t in °C; and p(t) is the given allulose purity of the mother liquor at the time point t in percentage points; (c3) determining the ratio B(t) / B(t)cr and comparing it with a predetermined threshold H value; when the ratio B(t) / B(t) deviates from the predetermined threshold H value:cr (c4) determining a target temperature of the mother liquor Ttarget, which is defined by formula (8) ( ) ^^ ^^2( ) ^^ = −7.1 − 0.763 ∙ − 1.031 ∙ ^^ ^^ + 0.02166 ∙ + 0.00821 ∙ ^^(^^)^^^^^^^^^^^^^^(8) wherein B(t) is the given Brix value of the mother liquor B(t) at the time point t; H is the predetermined threshold value; and p(t) is the given allulose purity of the mother liquor at the time point t; and 5target(c ) adjusting the temperature of the mother liquor to T ; preferably wherein the predetermined threshold value H is within the range of 1.03 to 1.06, prefer- ably 1.04 to 1.06.

[0355] The process according to the invention may essentially consist of steps (a), (b) and (c). Step (d):

[0356] In preferred embodiments, the process according to the invention additionally comprises the step of (d) separating crystalline allulose from the mother liquor.

[0357] Crystalline allulose may be separated from the mother liquor by any known solid-liquid separa- tion technology such as centrifugation filtration, and the like.

[0358] Preferably, the thus separated crystalline allulose is subsequently dried, preferably under re- duced pressure and / or at elevated temperature.

[0359] It has been found that viscosity of the magma (liquid phase + allulose crystals, i.e. slurry, sus- pension) correlates with crystal content, temperature and dry substance content of the liquid phase. Pu- rity of the liquid phase may also have an impact on viscosity.

[0360] Preferably, the viscosity of the magma is at most 50 Pa·s, preferably at most 45 Pa·s, more preferably at most 40 Pa·s, still more preferably at most 35 Pa·s, yet more preferably at most 30 Pa·s,even more preferably at most 29 Pa·s, most preferably at most 28 Pa·s, and in particular at most 27 Pa·s, at any point in time during the process according to the invention. Viscosity of the magma may be measured by methods that are known to the skilled person, preferably in accordance with ICUMSA SPS-5 (1994) Part 3: Rheological Measurements on Molasses. Preferably, viscosity of the magma is measured by means of by means of process viscosimeter ReactaVisc RV3 (Gecko Instruments, Grasbrunn Germany).

[0361] Preferably, the color of the liquid phase is at most 15,000, preferably at most 14,000 IU, more preferably at most 13,000 IU, still more preferably at most 12,000 IU, yet more preferably at most 11,000 IU, even more preferably at most 10,000 IU, most preferably at most 9,000 IU, and in particular at most 8,000 IU, at any point in time during the process according to the invention. The color of the liquid phase may be measured by methods that are known to the skilled person, e.g. according to ICUMSA method GS1-7 (2024). Crystalline product:

[0362] Another aspect of the invention relates to a crystalline allulose that is obtained by or obtainable by the process according to the invention as described above; preferably wherein the crystalline allulose is characterized by an x-ray diffractogram determined at 23°C with Cu kα radiation within the range of from about 12.8 to about 76.5 °2θ comprising - a first x-ray reflection with the greatest intensity of all x-ray reflections and - a second x-ray reflection with the second greatest intensity of all x-ray reflections, wherein the first x-ray reflection or the second x-ray reflection is at 31.0±0.1 °2θ.

[0363] Another aspect of the invention relates to a crystalline allulose that is characterized by an x-ray diffractogram determined at 23°C with Cu kα radiation within the range of from about 12.8 to about 76.5 °2θ comprising - a first x-ray reflection with the greatest intensity of all x-ray reflections and - a second x-ray reflection with the second greatest intensity of all x-ray reflections, wherein the first x-ray reflection or the second x-ray reflection is at 31.0±0.1 °2θ.

[0364] For the purpose of the specification, unless expressly stated otherwise, all intensities of x-ray reflections are baseline corrected.

[0365] The crystallized allulose obtained in step (c) has essentially the same characteristics as the crys- tallized allulose obtained in step (d). For the purpose of the specification, the expressions "crystallized allulose obtained in step (c)" and "crystallized allulose obtained in step (d)" can be used interchangea- bly.

[0366] For the purpose of the specification, the following definitions likewise apply to the allulose crystallized by the process according to the invention, i.e. to crystallized allulose obtained in step (c) and to crystallized allulose obtained in step (d) (commonly referred to as "crystallized allulose"), andalso the crystalline allulose according to the invention. Thus, for the purpose of the specification, all preferred embodiments of the crystallized allulose described herein also analogously apply to corre- sponding embodiments of the crystalline allulose according to the invention.

[0367] Preferably, the first x-ray reflection is at one of 15.4±0.1 and 31.0±0.1 °2θ, and wherein the second x-ray reflection is at the other one of 15.4±0.1 and 31.0±0.1 °2θ.

[0368] Preferably, the first x-ray reflection is at 15.4±0.1 °2θ.

[0369] Preferably the second x-ray reflection is at 31.0±0.1 °2θ.

[0370] Preferably the x-ray diffractogram comprises - a third x-ray reflection having the third greatest intensity of all x-ray reflections and - a fourth x-ray reflection having the fourth greatest intensity of all x-ray reflections, wherein the third x-ray reflection or the fourth x-ray reflection is at 47.2±0.1 °2θ.

[0371] Preferably the third x-ray reflection is at 47.2±0.1 °2θ.

[0372] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X50,r determined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, of at least 50 µm, preferably at least 60 µm, more preferably at least 65 µm, still more preferably at least 70 µm, yet more preferably at least 75 µm, even more preferably at least 80 µm, most preferably at least 85 µm, and in particular at least 90 µm.

[0373] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X50,r determined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, of at most 600 µm, preferably at most 550 µm, more preferably at most 500 µm, still more preferably at most 450 µm, yet more preferably at most 400 µm, even more preferably at most 350 µm, most preferably at most 300 µm, and in particular at most 250 µm.

[0374] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X50,r determined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, within the range of 200±180 µm, preferably 200±160 µm, more preferably 200±140 µm, still more preferably 200±120 µm, yet more preferably 200±100 µm, even more preferably 200±80 µm, most preferably 200±60 µm, and in particular 200±40 µm.

[0375] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X50,rdetermined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, within the range of 300±180 µm, preferably 300±160 µm, more preferably 300±140 µm, still more preferably 300±120 µm, yet more preferably 300±100 µm, even more preferably 300±80 µm, most preferably 300±60 µm, and in particular 300±40 µm.

[0376] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X50,rdetermined by dynamic image analysis according to ISO 13322-2, preferably with adispersion pressure of 20 kPa, within the range of 400±180 µm, preferably 400±160 µm, more prefera- bly 400±140 µm, still more preferably 400±120 µm, yet more preferably 400±100 µm, even more pref- erably 400±80 µm, most preferably 400±60 µm, and in particular 400±40 µm.

[0377] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X10,r determined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, of at least 50 µm, preferably at least 60 µm, more preferably at least 65 µm, still more preferably at least 70 µm, yet more preferably at least 75 µm, even more preferably at least 80 µm, most preferably at least 85 µm, and in particular at least 90 µm.

[0378] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X10,r determined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, of at most 600 µm, preferably at most 550 µm, more preferably at most 500 µm, still more preferably at most 450 µm, yet more preferably at most 400 µm, even more preferably at most 350 µm, most preferably at most 300 µm, and in particular at most 250 µm.

[0379] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X10,r determined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, within the range of 200±180 µm, preferably 200±160 µm, more preferably 200±140 µm, still more preferably 200±120 µm, yet more preferably 200±100 µm, even more preferably 200±80 µm, most preferably 200±60 µm, and in particular 200±40 µm.

[0380] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X90,r determined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, of at least 50 µm, preferably at least 100 µm, more preferably at least 150 µm, still more preferably at least 200 µm, yet more preferably at least 250 µm, even more preferably at least 300 µm, most preferably at least 350 µm, and in particular at least 400 µm.

[0381] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X90,rdetermined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, of at most 1000 µm, preferably at most 950 µm, more preferably at most 900 µm, still more preferably at most 850 µm, yet more preferably at most 800 µm, even more preferably at most 750 µm, most preferably at most 700 µm, and in particular at most 650 µm.

[0382] Preferably, the crystallized allulose or crystalline allulose has a particle size distribution with a value for X90,rdetermined by dynamic image analysis according to ISO 13322-2, preferably with a dis- persion pressure of 20 kPa, within the range of 450±225 µm, preferably 450±200 µm, more preferably 450±175 µm, still more preferably 450±150 µm, yet more preferably 450±125 µm, even more preferably 450±100 µm, most preferably 450±75 µm, and in particular 450±50 µm.

[0383] Preferably, the crystallized allulose or crystalline allulose has a particle shape with a b / l value (breadth / length) determined by dynamic image analysis according to ISO 13322-2, preferably with adispersion pressure of 20 kPa, of at least 0.20, preferably at least 0.25, more preferably at least 0.30, still more preferably at least 0.35, yet more preferably at least 0.40, even more preferably at least 0.45, most preferably at least 0.50, and in particular at least 0.55.

[0384] Preferably, the crystallized allulose or crystalline allulose has a particle shape with a b / l value (breadth / length) determined by dynamic image analysis according to ISO 13322-2, preferably with a dispersion pressure of 20 kPa, of at most 1.00, preferably at most 0.95, more preferably at most 0.90, still more preferably at most 0.85, yet more preferably at most 0.80, even more preferably at most 0.75, most preferably at most 0.70, and in particular at most 0.65.

[0385] Preferably, the crystallized allulose or crystalline allulose has a particle shape with a b / l value (breadth / length) determined by dynamic image analysis according to ISO 13322-2, preferably with a dispersion pressure of 20 kPa, within the range of 0.60±0.40, preferably 0.60±0.35, more preferably 0.60±0.30, still more preferably 0.60±0.25, yet more preferably 0.60±0.20, even more preferably 0.60±0.15, most preferably 0.60±0.10, and in particular 0.60±0.05. LIST OF REFERENCE NUMERALS 1 - isothermal crystallizer 2 - cooling crystallizer 3 - mother liquor 4 - allulose crystals 5 - another mother liquor EXAMPLES

[0386] The following examples further illustrate the invention but are not to be construed as limiting its scope:

[0387] Example A - crystallization from different mother liquors under different conditions:

[0388] Examples A1 and A2 are comparative examples involving cooling crystallization. Examples A3, A4, A5 and A6 are inventive examples.

[0389] Experimental conditions and results are compiled in the table here below:comparative inventive Ex. A1 Ex. A2 Ex. A3 Ex. A4 Ex. A5 Ex. A6 seed d50 [µm] 8 8 5.65 8 4.5 5.65 seed weight [kg] 0.400 0.400 0.040 0.400 0.00038 0.030 (a) p0 [%] 90 98 84 86 99 95.3 B0 [%] 81.5 82 82.8 81.2 82.2 81.5 T0[°C] 43 51 36 32 41.5 38 t1[h] - - 25 20 16 17 (b) p1[%] - - 80.8 83 98.97 94.7 B1 [%] - - 81 78.9 81 80 T1 [°C] - - 36 32 41.5 38 t2 [h] - - 27 25 16 42 (c) p2 [%] - - 73 78.7 98.2 91.1 B2[%] - - 77.3 75.9 73.1 72.8 T2[°C] - - 24.4 23.7 23.6 20 ttotal[h] 105 (p) 105 53 45 32 59 product yield [%] n.d. 46% 45 45 50 50 product d50 [µm] - 453 (sfp) 337 (sfp) 296 (sfp) 303 (fp) 380 (fp) crystals Figure 4A 5A 6A 7A 8A 9A profile Figure 4B 5B 6B 7B 8B 9B p.: planned n.d.: not determined sfp.: semi-finished product containing agglomerates fp.: finished product not containing agglomerates

[0390] Comparative Examples A1 and A2 involved cooling crystallization at a cooling rate of 0.2°C / h for a planned duration of 105 h.

[0391] Under the conditions of Comparative Example A1, formation of fine crystals was observed thereby resulting in dissipation of a significant amount of heat. As cooling capacity was not sufficient, after about 80 h the cooling rate of 0.2°C / h could not be maintained any longer and in consequence, the total time of 105 h could not be achieved (see plateau in Figure 4B). Comparative Example A1 demon- strates the disadvantages that are observed when the cooling rate is static, i.e. not dynamically adjusted in accordance with the given supersaturation.

[0392] Under the conditions of Comparative Example A2, cooling capacity was sufficient and crystal size was relatively uniform. Allulose purity in the starting material was high and crystallization time was long.

[0393] Inventive Examples A3, A4, A5 and A6 demonstrate that the process according to the invention provides a uniform crystalline product within short crystallization times tolerating comparatively poor allulose purities in the starting material.

[0394] A comparison of Inventive Example A4 with Comparative Example A2 demonstrates the ad- vantages of the process according to the invention. Although in Inventive Example A4 the allulose purity in the starting material is inferior (86% vs. 98%), a significantly faster crystallization can be achieved with the same amount and quality of seeds (weight and size) (45 h vs.105 h).

[0395] Example B - preparation of mother liquors from raw syrups having different pH values:

[0396] Different mother liquors were provided by evaporating water from raw syrups. The influence of the pH value of the raw syrups prior to evaporation of water and after evaporation of water on space- time yield and crystal shape was investigated under otherwise identical conditions.

[0397] The results are compiled in the following table and shown in Figure 10 A through C: time space-time-yield ^̅^ [h] [kg Figure 1 crystal m-3h-1] [°C h-1] 0 Ex. B1 pH 4 prior to evaporation 55 10 0.37 A Ex. B2 pH 4 after evaporation 36 17 1 B Ex. B3 reference pH 6 32 20 1.2 C

[0398] It was found that an acidic pH prior to evaporation (Ex. B1, pH 4) significantly decreases space- time-yield and extends crystal length.

[0399] Thus, it is advantageous to adjust the pH value of the raw syrup prior to evaporation to a pH value above 4.

[0400] Example C - development of a crystallization model:

[0401] a) Theoretical considerations and fitting

[0402] Supersaturation influences the speed of crystal growth. Incorporation-limited crystal growth and diffusion-limited crystal growth can be distinguished. The following models have been developed to describe crystal growth: polynuclear (PN), mononuclear (MN), birth and spread (B+S), and Burton- Cabrera-Frank (BCF).

[0403] The growth rate of allulose crystals was approximated using the d³ rule and plotted against su- persaturation. Figure 11 shows the crystal growth rate as a function of supersaturation (n = 9). Different growth zones could be identified. As shown in Figure 11, the growth rate increases with increasing supersaturation. At a supersaturation ratio < 1.03 the slope of the growth rate is greater than within the range of from 1.03 to 1.06. This behavior can also be observed in the BCF model, where the slope of the growth rate flattens as supersaturation increases. At a supersaturation ratio > 1.06, the slope of the growth rate significantly increases. This behavior can also be observed in the PN model.

[0404] These experimental findings do not indicate that crystal growth is mainly limited by diffusion, as no purely linear increase in the growth rate is apparent and the growth rate shows a sharp increase above a supersaturation of 1.06, even though diffusion should increasingly limit the growth rate in this range in particular. The experimental data rather indicate that a combination of the BCF model and the PN model can be used to accurately describe crystal growth of allulose.

[0405] The following equations were sed for fitting: ^^

[0406] BCF (supersaturation ratio of allulose < 1.055): ^^^^^^^^ = ^^ ∙ (^^ − 1) ^^ ∙ ^^(^^−1)

[0407] PN (supersaturation ratio of allulose ≥ 1.055): ^^^^^^ = ^^′ ∙ (^^ − 1)^^

[0408] The following values were determined: A: 52.97, p: -1.50, B: -0.33, A’: 26447, and B’: 0.0094.

[0409] As shown in Figure 12, the simulation of the growth rate based on a combination of both models correlates very well with the actual value. Upper Figure 12 shows the course of the real and simulated growth rate versus supersaturation. Lower Figure 12 shows the course of the simulated growth rate versus the real growth rate. It appears that the BCF model provides a sufficiently accurate description of reality for a supersaturation ratio below 1.055 and the PN model for a supersaturation ratio of 1.055 and above.

[0410] The experimental data indicate that permanent crystallization in the PN range (≥ 1.055) is not advisable, as there may be an increased risk of secondary nucleation due to the rougher crystal surface. Therefore, crystallization below a supersaturation ratio of about 1.055 is advantageous. However, since secondary nucleation also depends on the crystal mass, seeding at a slightly higher supersaturation ratio of e.g. 1.065 is advantageous, as the reduction in process time is more important than the degree of secondary nucleation in this range.

[0411] Experiments confirmed that no increased fine particle formation is to be expected at a target supersaturation of 1.055.

[0412] Furthermore, increasing the stirrer speed to improve mass transfer should have no or only minor (positive) effects on the crystallization process, since crystallization should be mainly limited by the incorporation reaction in the target supersaturation range. Experiments confirmed that a higher stirrer speed had a negative impact, as secondary nucleation was increased.

[0413] b) Process model and fitting

[0414] In addition to the above theoretical considerations of crystal growth, a process model was de- veloped based on data from the crystal base and main crystallizations, which simulates the growth rate based on supersaturation, crystal volume fraction (Vc), and purity:

[0415] ^^ = ^^ ∙ (^^ − 1) ∙ (1 − ^^) ^^ ∙ ^^(^^∙(1−^^^^1)^^ )

[0416] The following values were determined: K: 370.8, n: 0.289, and L: -17.67.

[0417] The growth rates were again determined using the d3rule. The crystal volume fraction describes the volume fraction of the crystals in the total volume. A crystal density of 1589 kg m-3was assumed for this purpose. A total of 72 data points were available, with the data set randomly divided into training data (69%) and validation data (31%). The parameters K, n, and L were then determined using the training data.

[0418] Figure 13 shows the result of the modeling. The course of the simulated (y_pred) growth rate was compared to the actual (y) growth rate, including regression line, 95% confidence interval (CI) and prediction interval (PI).

[0419] The coefficient of determination of the regression (R²Reg) was approximately 0.91. This means that approximately 91% of the variability in the data can be explained by the model, which corresponds to a high degree of accuracy in the crystallization area.

[0420] The coefficient of determination of the validation data (R²Val) was approximately 0.80. This means that the difference between the two coefficients of determination is 0.11 and is therefore close to each other. Therefore, no overfitting can be assumed. In general, a difference between R²Reg and R²Val of less than 0.2 is recommended to guarantee sufficient model quality. In summary, the model should therefore be able to determine the crystal growth rate with an accuracy of approximately 80%.

[0421] To determine the universal validity of the model, three additional process data sets (batches K09012025, KRDA004, and K0069) were examined. The aim was to investigate the transfer of the model to different scales, designs (geometry, stirrer), and crystallization conditions.

[0422] Figure 14 shows the course of the simulated growth rate compared to the actual growth rate of the process data sets from the batches K09012025, KRDA004, and K0069.

[0423] Despite significant differences in the process conditions, the model has a mean coefficient of determination of 0.80 and thus corresponds exactly to the coefficient of determination of the validation data. It can therefore be concluded that the model initially has a sufficiently high quality to estimate the influence of changes in the process (e.g., by increasing the crystal base mass, reducing the purity in the raw syrup, increasing the target supersaturation) prior to process changes and to anticipate their influ- ence on crystallization.

[0424] In experiments the target supersaturation was increased from 1.040 to 1.050. According to the process model, this should have led to a reduction in the cooling phase of approximately 25% (9 hours). In reality, a reduction of 22% (8 hours) was observed, which is highly consistent with the prediction. This further supports the validity of the BCF model. Using the BCF model, an increase in the target supersaturation from 1.040 to 1.050 would have been expected to reduce the cooling phase by approxi- mately 26%. A further increase in the target supersaturation from 1.050 to 1.055 should reduce the cooling phase by approximately 9%.

[0425] Example D - crystal habit:

[0426] Crystallizations D1 through D5 were each performed in two stages in accordance with the in- vention.

[0427] A single crystallizer was used for both purposes, i.e., as isothermal crystallizer and also as cool- ing crystallizer. In accordance with the embodiment illustrated in Figure 16, step (b) was performed in an isothermal crystallizer and step (c) was performed in a cooling crystallizer that was separate from theisothermal crystallizer. Step (b) involved at the end of the first time interval transferring a fraction of the suspension that was contained in the isothermal crystallizer into the cooling crystallizer.

[0428] After isothermal crystallization (first stage, step (b)), the product obtained in step (b) was mixed with another mother liquor and cooling crystallization was continued starting from the mixture.

[0429] For practical reasons, due to the mixing with another mother liquor, temperature, Brix, viscosity and crystal content at the end of isothermal crystallization (first stage, step (b)) only resembled but were not absolutely identical to temperature, Brix, viscosity and crystal content at the start of subsequent cooling crystallization (second stage, step (c)).

[0430] Crystallization D6 was likewise performed in two stages in accordance with the invention as isothermal crystallization (first stage, step (b)) and subsequent cooling crystallization (second stage, step (c)). However, no another mother liquor was added. Thus, crystallization D6 was performed in accord- ance with the embodiment illustrated in Figure 15.

[0431] Details for crystallizations D1 through D6 are compiled in the below table: pstart Tstart Tend Bstart Bend ccstart ccend t [%] [°C] [%] [wt.-%] [h] 1. 98.8 44.4 44.4 83.4 79.6 0.0 27.0 17.5 D1 2. 99.0 45.1 34.0 82.1 77.6 10.6 45.9 7.5 1. 98.6 46.1 46.1 84.0 79.9 0.0 29.1 20.1 D2 2. 98.1 44.8 33.2 82.2 77.4 7.5 41.8 12.3 1. 99.0 47.1 47.1 84.3 80.0 0.0 31.0 21.2 D3 2. 96.6 46.6 35.7 83.0 78.9 10.4 45.1 12.6 1. 99.2 47.9 47.9 84.7 80.3 0.0 32.4 20.9 D4 2. 95.9 46.5 36.1 83.0 78.9 10.8 46.4 15.7 D5 1. 99.2 47.6 47.6 84.8 80.4 0.0 32.7 21.1 2. 94.1 44.2 32.5 82.4 78.0 11.0 46.8 21.2 D6 1. 94.7 38.2 38.2 81.9 80.8 0.0 8.8 30.0 2. 94.1 38.2 21.4 80.8 73.6 8.8 41.1 40.2 p: purity; T: temperature; B: Brix; cc: crystal content; t: duration

[0432] Representative samples were withdrawn from the crystallizer while stirring. Withdrawn samples were centrifuged for 15 minutes at room temperature by means of a filter centrifuge (Hermle SIEVA®3) at 1400 g. A filter tissue with a pore size of 20 µm was used (PP 2474, Otto Markert & Sohn GmbH). After 8 minutes, samples were washed during centrifugation with isopropanol (100%) at room temper- ature. After centrifugation, the content of the filter tissue was poured onto paper, evenly spread and dried under ambient conditions for at least 24 hours. Samples were not grinded.

[0433] Particle size distributions (PSD) were determined by image analysis according to ISO 13322-2 with a dispersion pressure of 20 kPa.

[0434] Crystal structures were characterized by X-ray diffraction (XRD) using Cu Kαirradiation (1.54056 Å) at room temperature.

[0435] The analytical details were as follows: - Diffractometer: PANalytical EMPYREAN, QS No.02397 - Geometry: Bragg-Brentano (reflection) - Detector: Pixcel (3D) - Radiation: Cu Kα (1.54056 Å) - Tube settings: 40 kV, 40 mA - Measuring range: 5-80° 2Theta - Step size: 0.013° 2Theta - Measuring time per step: 25 s - Sample preparation: none - Preparation: powder bed - Evaluation software: PANalytical HighScorePlus - Reference database: ICDD PDF-5+ (2025) / external standard comparisons - Evaluation according to: DIN EN 13925:2003: X-ray diffraction of polycrystalline and amorphous materials

[0436] Experimental results are compiled in the below table, wherein no.1 through 6 indicate in each diffractogram the six x-ray reflections having the greatest relative intensities (baseline corrected):PSD XRD sample [µm] baseline corrected X10,rX50,rX90b / l no.,rintensity [%] °2θ 1 100.0 18.8 2 61.8 15.4 3 37.0 23.0 D1{1} 144 243 361 0.681 4 33.3 32.0 5 26.7 15.2 6 25.7 29.8 1 100.0 15.4 2 42.9 31.0 3 25.6 47.2 D1{1+2} 169 288 409 0.623 4 14.8 18.9 5 10.9 32.0 6 10.5 38.8 1 100.0 15.4 2 36.7 30.9 3 17.2 47.1 D2{1+2} 213 357 522 0.577 4 10.4 15.3 5 1.4 34.0 6 1.2 55.3 1 100.0 15.4 2 37.8 30.9 3 18.2 47.2 D3{1+2} 172 310 476 0.572 4 2.2 40.7 5 2.0 48.0 6 1.9 20.5 1 100.0 15.3 2 36.0 30.9 3 17.4 47.1 D4{1+2} 189 358 560 0.582 4 9.0 18.8 5 6.7 48.0 6 5.2 38.8 1 100.0 15.3 2 39.6 30.9 3 18.6 47.1 D5{1+2} 147 280 450 0.544 4 16.0 15.3 5 3.1 23.0 6 1.6 40.6 1 100.0 15.5 2 50.2 31.1 3 35.0 15.4 D6{1+2} 295 531 767 0.638 4 28.4 47.3 5 24.2 31.0 6 11.2 47.2

[0437] Sample D1{1} was obtained (intermediate) after the first stage (isothermal crystallization, {1}) without subsequent second stage (cooling crystallization, {2}). Thus, sample D1{1} is a comparative example.

[0438] Samples D1{1+2} through D6{1+2} were obtained (final products) after the first stage (isother- mal crystallization, {1}) followed by the subsequent second stage (cooling crystallization, {2}). Thus, sample D1{1+2} through D6{1+2} are inventive examples.

[0439] As demonstrated, the x-ray reflection having the greatest intensity is at 15.4±0.1 °2θ, whereas the x-ray reflection having the second greatest intensity is at 31.0±0.1 °2θ. For samples D1{1+2} through D5{1+2}, the x-ray reflection having the third greatest intensity is at 47.2±0.1 °2θ, whereas for sample D6{1+2} it is the x-ray reflection having the fourth greatest intensity.

[0440] The crystallized allulose obtained by the process according to the invention is clearly distin- guished from crystallized allulose that is known from the prior art, e.g. from EP 3647317 A1 and WO 2024 / 144004.

[0441] In the below tables, relative intensities and °2θ values according to the prior art are summarized. While in some cases the x-ray reflection having the greatest intensity is also at 15.4±0.1 °2θ, the x-ray reflection having the second greatest intensity differs from 31.0±0.1 °2θ. Further, an x-ray reflection at 47.2±0.1 °2θ is not among the reflections having the greatest intensities, or does not even exist:

[0442] EP 3647317 A1, Table 4: Crystal of Example 1 Crystal of Example 2 Crystal of Example 3 relative relative relative intensity °2θ intensity °2θ intensity °2θ 100.0 18.78 100.0 15.27 100.0 15.28 97.6 15.24 30.5 18.77 30.5 18.79 18.8 30.84 20.2 30.87 23.3 30.87 9.5 28.37 9.7 22.90 12.1 22.90 9.0 31.87 9.1 31.88 7.6 33.93 4.1 47.06 7.0 47.08 4.6 47.09

[0443] WO 2024 / 144004 (AU 2023414816 A1), Table 2: Comp. Ex.1 Comp. Ex.2 Comp. Ex.3 Comp. Ex.4 Example 1 Example 2 rel. rel. rel. rel. rel. rel. int. °2θ int. °2θ int. °2θ int. °2θ int. °2θ int. °2θ 100 15.3 100 15.2 100 15.2 100 15.2 100 18.8 100 18.8 11.7 18.8 55.0 18.7 46.9 18.7 86.0 18.8 89.1 15.2 34.2 15.2 4.4 30.9 13.7 30.8 16.6 30.8 20.2 30.8 17.5 19.5 11.8 19.5 2.8 47.2 8.3 29.8 4.9 28.6 11.1 19.5 11.8 28.4 7.6 20.3

[0444] Example E - crystal stability upon storage and shipping:

[0445] Crystallized allulose that was prepared according to the process of the invention was packaged in big bags and stored at ambient temperature. The big bags had a volume of about 1000 liters and were completely filled with crystallized allulose.

[0446] Samples were taken from a top layer of the big bag, a middle layer of the big bag, and a bottom layer of the big bag. The aim of this study was to investigate the influence of packaging and storage on the crystal habit.

[0447] The samples were analyzed by XRD in accordance with Example D.

[0448] Results are compiled in the below table: sample no. baseline corrected intensity [%] °2θ @ 1 100.0 15.4 2 32.5 31.0 big bag 3 24.6 34.0 top layer 4 16.3 47.2 5 13.4 18.9 6 12.8 32.0 1 100.0 15.4 2 34.1 31.0 big bag 3 17.8 47.2 middle layer 4 8.0 18.9 5 6.5 20.5 6 5.8 34.0 1 100.0 15.5 2 46.4 31.1 big bag 3 23.2 47.3 bottom layer 4 9.6 19.0 5 9.1 39.9 6 7.6 34.1

Claims

Patent claims:

1. A process for the crystallization of allulose comprising the steps of (a) providing a mother liquor comprising allulose having a temperature T0within the range of from 20 to 60°C; an allulose purity p0 of at least 70 wt.-%; and a Brix value B0 (temperature corrected, calibrated for sucrose) of at least 75.0 °Bx; (b) crystallizing allulose from the mother liquor during a first time interval under substantially isothermal conditions until a predetermined quantity q1 of allulose has been crystallized from the mother liquor; and (c) crystallizing allulose from the mother liquor during a second time interval following the first time interval, wherein at any time during the second time interval the temperature of the mother liquor is below T0.

2. The process according to claim 1, wherein the mother liquor provided in step (a) is supersaturated; preferably wherein the supersaturation ratio of allulose is at least 1.03, more preferably within the range of from 1.03 to 1.15, still more preferably 1.04 to 1.

08.

3. The process according to claim 2, wherein the supersaturation ratio of allulose in the mother liquor provided in step (a) is at least 1.035, more preferably at least 1.040, still more preferably at least 1.045, yet more preferably at least 1.050, even more preferably at least 1.055, most preferably at least 1.060, and in particular at least 1.

065.

4. The process according to claim 2 or 3, wherein, the supersaturation ratio of allulose in the mother liquor provided in step (a) is at most 1.095, more preferably at most 1.090, still more preferably at most 1.085, yet more preferably at most 1.080, even more preferably at most 1.075, most pref- erably at most 1.070, and in particular at most 1.

065.

5. The process according to any of claims 2 to 4, wherein the supersaturation ratio of allulose is determined by measuring refractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor provided in step (a); preferably Brix value.

6. The process according to any of claims 2 to 5, wherein the supersaturation ratio of allulose is determined by measuring allulose purity p0of the mother liquor provided in step (a); by measuring Brix value B0of the mother liquor provided in step (a); by measuring temperature T0of the mother liquor provided in step (a); by determining allulose concentration in the mother liquor provided in step (a) from the measured values for p0and B0; and by determining allulose solubility at the measured purity p0and at the measured temperature T0from calibration curves that have been measured with mother liquors of known allulose concentration and known allulose purity.

7. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a critical Brix value B0crwhich is defined by formula (1): ^^ 2^^^^^^ = 53.71 + 0.399 ∙ ^^^^ + 0.375 ∙ ^^^^ − 0.001551 ∙ ^^^^ − 0.003302 ∙ ^^2^^ + 0.001185 ∙ ^^^^ ∙ ^^^^(1) wherein T0 is the given temperature of the mother liquor in °C and p0 is the given allulose purity of the mother liquor in percentage points; and wherein the ratio B0 / B0cr is at least 1.

03.

8. The process according to claim 7, wherein the ratio B0 / B0cr is at least 1.04, preferably at least 1.05, more preferably at least 1.06, still more preferably at least 1.07, yet more preferably at least 1.08, even more preferably at least 1.09, most preferably at least 1.10, and in particular at least 1.

11.

9. The process according to claim 7 or 8, wherein the ratio B0 / B0cr is at most 1.13, preferably at most 1.12, more preferably at most 1.11, still more preferably at most 1.10, yet more preferably at most 1.09, even more preferably at most 1.08, most preferably at most 1.07, and in particular at most 1.

06.

10. The process according to any of claims 7 to 9, wherein the ratio B0 / B0cr is within the range of from 1.03 to 1.15, preferably 1.04 to 1.

08.

11. The process according to any of the preceding claims, wherein T0 is at least 20°C, preferably at least 21°C, more preferably at least 22°C, still more preferably at least 23°C, yet more preferably at least 24°C, even more preferably at least 25°C, most preferably at least 26°C, and in particular at least 27°C.

12. The process according to any of the preceding claims, wherein T0 is at least 28°C, preferably at least 29°C, more preferably at least 30°C, still more preferably at least 31°C, yet more preferably at least 32°C, even more preferably at least 33°C, most preferably at least 34°C, and in particular at least 35°C.

13. The process according to any of the preceding claims, wherein T0 is at most 55°C, preferably at most 54°C, more preferably at most 53°C, still more preferably at most 52°C, yet more preferably at most 51°C, even more preferably at most 50°C, most preferably at most 49°C, and in particular at most 48°C.

14. The process according to any of the preceding claims, wherein T0is within the range of from 30 to 60°C.

15. The process according to any of the preceding claims, wherein T0 is within the range of 30±10°C, preferably 30±9°C, more preferably 30±8°C, still more preferably 30±7°C, yet more preferably 30±6°C, even more preferably 30±5°C, most preferably 30±4°C, and in particular 30±3°C.

16. The process according to any of claims 1 to 14, wherein T0 is within the range of 35±10°C, pref- erably 35±9°C, more preferably 35±8°C, still more preferably 35±7°C, yet more preferably 35±6°C, even more preferably 35±5°C, most preferably 35±4°C, and in particular 35±3°C.

17. The process according to any of claims 1 to 14, wherein T0 is within the range of 40±10°C, pref- erably 40±9°C, more preferably 40±8°C, still more preferably 40±7°C, yet more preferably 40±6°C, even more preferably 40±5°C, most preferably 40±4°C, and in particular 40±3°C.

18. The process according to any of claims 1 to 14, wherein T0 is within the range of 45±10°C, pref- erably 45±9°C, more preferably 45±8°C, still more preferably 45±7°C, yet more preferably 45±6°C, even more preferably 45±5°C, most preferably 45±4°C, and in particular 45±3°C.

19. The process according to any of the preceding claims, wherein B0 is at least 75.2 °Bx, preferably at least 75.4 °Bx, more preferably at least 75.6 °Bx, and still more preferably at least 75.8 °Bx.

20. The process according to any of the preceding claims, wherein B0 is at least 76.0 °Bx, preferably at least 76.2 °Bx, more preferably at least 76.4 °Bx, still more preferably at least 76.6 °Bx, yet more preferably at least 76.8 °Bx, even more preferably at least 77.0 °Bx, most preferably at least 77.2 °Bx, and in particular at least 77.4 °Bx.

21. The process according to any of the preceding claims, wherein B0 is at least 77.6 °Bx, preferably at least 77.8 °Bx, more preferably at least 78.0 °Bx, still more preferably at least 78.2 °Bx, yet more preferably at least 78.4 °Bx, even more preferably at least 78.6 °Bx, most preferably at least 78.8 °Bx, and in particular at least 79.0 °Bx.

22. The process according to any of the preceding claims, wherein B0 is at least 79.2 °Bx, preferably at least 79.4 °Bx, more preferably at least 79.6 °Bx, still more preferably at least 79.8 °Bx, yet more preferably at least 80.0 °Bx, even more preferably at least 80.2 °Bx, most preferably at least 80.4 °Bx, and in particular at least 80.6 °Bx.

23. The process according to any of the preceding claims, wherein B0is at least 80.8 °Bx, preferably at least 81.0 °Bx, more preferably at least 81.2 °Bx, still more preferably at least 81.4 °Bx, yet more preferably at least 81.6 °Bx, even more preferably at least 81.8 °Bx, most preferably at least 82.0 °Bx, and in particular at least 82.2 °Bx.

24. The process according to any of the preceding claims, wherein B0is at least 82.4 °Bx, preferably at least 82.6 °Bx, more preferably at least 82.8 °Bx, still more preferably at least 83.0 °Bx, yetmore preferably at least 83.2 °Bx, even more preferably at least 83.4 °Bx, most preferably at least 83.6 °Bx, and in particular at least 83.8 °Bx.

25. The process according to any of the preceding claims, wherein B0 is at least 84.0 °Bx, preferably at least 84.2 °Bx, more preferably at least 84.4 °Bx, still more preferably at least 84.6 °Bx, yet more preferably at least 84.8 °Bx, even more preferably at least 85.0 °Bx, most preferably at least 85.2 °Bx, and in particular at least 85.4 °Bx.

26. The process according to any of the preceding claims, wherein B0 is at most 88.0 °Bx, preferably at most 87.8 °Bx, more preferably at most 87.6 °Bx, still more preferably at most 87.4 °Bx, yet more preferably at most 87.2 °Bx, even more preferably at most 87.0 °Bx, most preferably at most 86.8 °Bx, and in particular at most 86.6 °Bx.

27. The process according to any of the preceding claims, wherein B0 is within the range of from 80.0 to 85.0 °Bx.

28. The process according to any of the preceding claims, wherein p0 is at least 72.5 wt.-%, preferably at least 75.0 wt.-%, more preferably at least 77.5 wt.-%, still more preferably at least 80.0 wt.-%, yet more preferably at least 82.5 wt.-%, even more preferably at least 85.0 wt.-%, most preferably at least 87.5 wt.-%, and in particular at least 90.0 wt.-%, relative to the total dry solids content of the mother liquor.

29. The process according to any of the preceding claims, wherein p0 is quantified, preferably by HPLC.

30. The process according to any of the preceding claims, wherein p0 is at most 99.0 wt.-%, preferably at most 98.0 wt.-%, more preferably at most 97.0 wt.-%, still more preferably at most 96.0 wt.- %, yet more preferably at most 95.0 wt.-%, even more preferably at most 94.0 wt.-%, most pref- erably at most 93.0 wt.-%, and in particular at most 92.0 wt.-%, relative to the total dry solids content of the mother liquor.

31. The process according to any of the preceding claims, wherein p0is within the range of from 80.0 to 100.0%.

32. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) essentially consists of allulose, optionally fructose, optionally glucose, optionally inorganic salts, and optionally minor impurities.

33. The process according to any of the preceding claims, wherein in the mother liquor provided in step (a), allulose, optionally present fructose, optionally present glucose and optionally present inorganic salts have a total content of at least 96.0 wt.-%, preferably at least 97.0 wt.-%, more preferably at least 97.5 wt.-%, still more preferably at least 98.0 wt.-%, yet more preferably atleast 98.5 wt.-%, even more preferably at least 99.0 wt.-%, most preferably at least 99.5 wt.-%, and in particular at least 99.8 wt.-%, of the total dry solids content of the mother liquor provided in step (a).

34. The process according to any of the preceding claims, wherein in the mother liquor provided in step (a), the content of fructose is at most 22.5 wt.-%, preferably at most 20 wt.-%, more prefer- ably at most 17.5 wt.-%, still more preferably at most 15 wt.-%, yet more preferably at most 12.5 wt.-%, even more preferably at most 10 wt.-%, most preferably at most 7.5 wt.-%, and in partic- ular at most 5.0 wt.-% of the total dry solids content of the mother liquor provided in step (a).

35. The process according to any of the preceding claims, wherein in the mother liquor provided in step (a), the content of fructose is at most 5.0 wt.-%, preferably at most 4.5 wt.-%, more preferably at most 4.0 wt.-%, still more preferably at most 3.5 wt.-%, yet more preferably at most 3.0 wt.- %, even more preferably at most 2.5 wt.-%, most preferably at most 2.0 wt.-%, and in particular at most 1.5 wt.-% of the total dry solids content of the mother liquor provided in step (a).

36. The process according to any of the preceding claims, wherein in the mother liquor provided in step (a), the content of glucose is at most 3.5 wt.-%, preferably at most 3.0 wt.-%, more preferably at most 2.5 wt.-%, still more preferably at most 2.0 wt.-%, yet more preferably at most 1.5 wt.- %, even more preferably at most 1.0 wt.-%, most preferably at most 0.5 wt.-%, and in particular at most 0.1 wt.-% of the total dry solids content of the mother liquor provided in step (a).

37. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a pH value of at least 1.5, preferably at least 2.0, more preferably at least 2.5, still more preferably at least 3.0, yet more preferably at least 3.5, even more preferably at least 4.0, and most preferably at least 4.

5.

38. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a pH value of at most 9.5, preferably at most 9.0, more preferably at most 8.5, still more preferably at most 8.0, yet more preferably at most 7.5, even more preferably at most 7.0, and most preferably at most 6.

5.

39. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a pH value within the range of from 3.0 to 8.0, preferably 3.5 to 7.5, more preferably 4.0 to 7.0, still more preferably 4.5 to 6.

5.

40. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) is obtained by evaporating water from a raw syrup.

41. The process according to claim 40, wherein the raw syrup prior to evaporation has a pH value of at least 1.5, preferably at least 2.0, more preferably at least 2.5, still more preferably at least 3.0,yet more preferably at least 3.5, even more preferably at least 4.0, and most preferably at least 4.

5.

42. The process according to claim 40 or 41, wherein the raw syrup prior to evaporation has a pH value of at least 4.6, preferably at least 4.8, more preferably at least 5.0, still more preferably at least 5.2, yet more preferably at least 5.4, even more preferably at least 5.6, and most preferably at least 5.

8.

43. The process according to any of claims 40 to 42, wherein the raw syrup prior to evaporation has a pH value of at most 9.5, preferably at most 9.0, more preferably at most 8.5, still more preferably at most 8.0, yet more preferably at most 7.5, even more preferably at most 7.0, and most preferably at most 6.

5.

44. The process according to any of claims 40 to 43, wherein the raw syrup prior to evaporation has a pH value within the range of from 3.0 to 9.0, preferably 3.5 to 8.5, more preferably 4.0 to 8.0, still more preferably 4.5 to 7.5, even more preferably 5.0 to 7.0, most preferably 5.5 to 6.

5.

45. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) contains seed crystals of allulose.

46. The process according to claim 45, wherein the seed crystals have been prepared by milling, pref- erably by air vortex milling, air jet milling, or pin milling.

47. The process according to claim 45 or 46, wherein the content of the seed crystals is at least 0.01 ppmw, preferably at least 0.05 ppmw, more preferably at least 0.10 ppmw, still more preferably at least 0.15 ppmw, yet more preferably at least 0.20 ppmw, even more preferably at least 0.25 ppmw, most preferably at least 0.30 ppmw, and in particular at least 0.35 ppmw, relative to the allulose dry solids content of the mother liquor.

48. The process according to any of claims 45 to 47, wherein the content of the seed crystals is at most 0.9 wt.-%, preferably at most 0.8 wt.-%, more preferably at most 0.7 wt.-%, still more pref- erably at most 0.6 wt.-%, yet more preferably at most 0.5 wt.-%, even more preferably at most 0.4 wt.-%, most preferably at most 0.3 wt.-%, and in particular at most 0.2 wt.-%, relative to the allulose dry solids content of the mother liquor.

49. The process according to any of claims 45 to 48, wherein the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 of X µm, and wherein the content of the seed crystals is within the range of from (X·0.0114)3to (X·0.0116)3wt.-%, prefer- ably (X·0.0113)3to (X·0.0117)3, more preferably (X·0.0112)3to (X·0.0118)3, still more prefera- bly (X·0.0111)3to (X·0.0119)3, yet more preferably (X·0.0110)3to (X·0.0120)3, even morepreferably (X·0.0109)3to (X·0.0121)3, most preferably (X·0.0108)3to (X·0.0122)3, and in partic- ular (X·0.0107)3to (X·0.0123)3, relative to the allulose dry solids content of the mother liquor.

50. The process according to any of claims 45 to 49, wherein the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 of at least 5 µm, preferably at least 10 µm, more preferably at least 15 µm, still more preferably at least 20 µm, yet more preferably at least 25 µm, even more preferably at least 30 µm, most preferably at least 35 µm, and in particular at least 40 µm.

51. The process according to any of claims 45 to 50, wherein the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 of at most 85 µm, preferably at most 80 µm, more preferably at most 75 µm, still more preferably at most 70 µm, yet more preferably at most 65 µm, even more preferably at most 60 µm, most preferably at most 55 µm, and in particular at most 50 µm.

52. The process according to any of claims 45 to 51, wherein the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 within the range of 20±18 µm, preferably 20±16 µm, more preferably 20±14 µm, still more preferably 20±12 µm, yet more preferably 20±10 µm, even more preferably 20±8 µm, most preferably 20±6 µm, and in particular 20±4 µm.

53. The process according to any of claims 45 to 52, wherein the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 within the range of 30±18 µm, preferably 30±16 µm, more preferably 30±14 µm, still more preferably 30±12 µm, yet more preferably 30±10 µm, even more preferably 30±8 µm, most preferably 30±6 µm, and in particular 30±4 µm.

54. The process according to any of claims 45 to 53, wherein the seed crystals have an average particle size DV(50) determined by laser diffraction according to ISO 13320 within the range of 40±18 µm, preferably 40±16 µm, more preferably 40±14 µm, still more preferably 40±12 µm, yet more preferably 40±10 µm, even more preferably 40±8 µm, most preferably 40±6 µm, and in particular 40±4 µm.

55. The process according to any of claims 45 to 54, wherein the seed crystals are added as solids.

56. The process according to any of claims 45 to 54, wherein the seed crystals are added as suspen- sion / slurry.

57. The process according to claim 56, wherein the liquid phase of said suspension / slurry does not contain ethanol, more preferably not any organic solvents.

58. The process according to claim 56 or 57, wherein the suspensions / slurries have been obtained by a previous crystallization process, preferably in accordance with the invention.

59. The process according to any of claims 56 to 58, wherein seeding is achieved by means of seed crystals suspended in mother liquor (i.e. seed magma, seed massecuite, crystal foot, footing, crys- tal base, heel, and the like).

60. The process according to any of the preceding claims, wherein step (b) is performed batchwise.

61. The process according to any of claims 1 to 59, wherein step (b) is performed semi-batchwise or continuously.

62. The process according to any of the preceding claims, wherein at any point in time during the first time interval of step (b), the mother liquor is supersaturated; preferably wherein the supersatura- tion ratio is at least 1.

01.

63. The process according to claim 62, wherein at any point in time during the first time interval of step (b), the supersaturation ratio of allulose is at least 1.025, more preferably at least 1.030, still more preferably at least 1.035, yet more preferably at least 1.040, even more preferably at least 1.045, most preferably at least 1.050, and in particular at least 1.

055.

64. The process according to claim 62 or 63, wherein at any point in time during the first time interval of step (b), the supersaturation ratio of allulose is at most 1.085, more preferably at most 1.080, still more preferably at most 1.075, yet more preferably at most 1.070, even more preferably at most 1.065, most preferably at most 1.060, and in particular at most 1.

055.

65. The process according to any of the preceding claims, wherein at any time during the first time interval the temperature of the mother liquor is within the range of T0 ±3.0°C, preferably T0 ±2.7°C, more preferably T0 ±2.4°C, still more preferably T0 ±2.1°C, yet more preferably T0 ±1.8°C, even more preferably T0 ±1.5°C, most preferably T0 ±1.2°C, and in particular T0 ±0.9°C.

66. The process according to any of the preceding claims, wherein step (b) involves determining the quantity of allulose that has been crystallized from the mother liquor at a time point within the first time interval.

67. The process according to claim 66, wherein the quantity of allulose that has been crystallized is determined on the basis of refractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor; preferably Brix value.

68. The process according to claim 66 or 67, wherein the quantity of allulose that has been crystallized is determined by weighing precipitated solid.

69. The process according to any of the preceding claims, wherein the predetermined quantity q1 of crystallized allulose is at least 7.5 wt.-%, preferably at least 10 wt.-%, more preferably at least 12.5 wt.-%, still more preferably at least 15 wt.-%, yet more preferably at least 17.5 wt.-%, even more preferably at least 20 wt.-%, most preferably at least 22.5 wt.-%, and in particular at least 25 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

70. The process according to any of the preceding claims, wherein the predetermined quantity q1 of crystallized allulose is at most 35 wt.-%, preferably at most 32.5 wt.-%, more preferably at most 30 wt.-%, still more preferably at most 27.5 wt.-%, yet more preferably at most 25 wt.-%, even more preferably at most 22.5 wt.-%, most preferably at most 20 wt.-%, and in particular at most 17.5 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

71. The process according to any of the preceding claims, wherein the predetermined quantity q1 of crystallized allulose is within the range of 10 to 25 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

72. The process according to any of the preceding claims, wherein at the end of the first time interval the mother liquor is supersaturated; preferably wherein the supersaturation ratio of allulose is within the range of from 1.01 to 1.07, more preferably 1.02 to 1.06, still more preferably 1.03 to 1.

06.

73. The process according to claim 72, wherein at the end of the first time interval, the supersaturation ratio of allulose is at least 1.025, more preferably at least 1.030, still more preferably at least 1.035, yet more preferably at least 1.040, even more preferably at least 1.045, most preferably at least 1.050, and in particular at least 1.

055.

74. The process according to claim 72 or 73, wherein at the end of the first time interval, the super- saturation ratio of allulose is at most 1.085, more preferably at most 1.080, still more preferably at most 1.075, yet more preferably at most 1.070, even more preferably at most 1.065, most pref- erably at most 1.060, and in particular at most 1.

055.

75. The process according to any of claims 72 to 74, wherein supersaturation ratio of allulose is de- termined by measuring refractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor at the end of the first time interval; preferably Brix value.

76. The process according to claim 74 or 75, wherein the supersaturation ratio of allulose in the mother liquor during the first time interval of step (b) is determined - in knowledge of initial allulose purity p0of the mother liquor provided in step (a); - in knowledge of initial Brix value B0of the mother liquor provided in step (a); - by measuring Brix value B(t) of the mother liquor during the first time interval of step (b); - by measuring temperature T(t) of the mother liquor during the first time interval of step (b);- by determining allulose purity p(t) in the mother liquor during the first time interval of step (b) from the measured values for p0, B0,and B(t); - by determining allulose concentration in the mother liquor during the first time interval of step (b) from the measured values for p0, B0, and B(t); and - by determining allulose solubility at the determined purity p(t) and at the measured tempera- ture T(t) from calibration curves that have been measured with mother liquors of known allu- lose concentration and known allulose purity.

77. The process according to any of claims 74 to 76, wherein the relative difference of the supersat- uration ratio at the beginning of the first time interval to the supersaturation ratio at the end of the first time interval is at least 0.01, preferably at least 0.02, more preferably at least 0.03, still more preferably at least 0.04, yet more preferably at least 0.05, even more preferably at least 0.06, most preferably at least 0.07, and in particular at least 0.

08.

78. The process according to any of the preceding claims, wherein at the end of the first time interval the mother liquor has a Brix value B and a critical Brix value B which is defined by formula1 1cr (3): ^^ = 53.71 + 0.399 ∙ ^^ + 0.375 ∙ ^^ − 0.001551 ∙ ^^2 − 0.003302 ∙ ^^2^^^^^^ ^^ ^^ ^^ ^^ + 0.001185 ∙ ^^^^ ∙ ^^^^(3) wherein T is the given temperature of the mother liquor in °C, which essentially corresponds to1 T , and p is the given allulose purity of the mother liquor in percentage points; and wherein the0 1 ratio B / B is within the range of from 1.01 to 1.07, preferably 1.02 to 1.06, more preferably1 1cr 1.03 to 1.

06.

79. The process according to claim 78, wherein the given allulose purity p is defined by formula (4)1wherein m is the total weight of the mother liquor provided in step (a) in kg, B is the Brix value0 0 of the mother liquor provided in step (a) in °Bx, p is the allulose purity of the mother liquor0provided in step (a) in percentage points, and B1 is the Brix value of the mother liquor at the end of the first time interval in °Bx.

80. The process according to any of the preceding claims, wherein the difference B0 / B0cr - B1 / B1cr is at least 0.005, preferably at least 0.010, more preferably at least 0.

015.

81. The process according to any of the preceding claims, wherein the difference B0 / B0cr - B1 / B1cr is at most 0.07, preferably at most 0.06, more preferably at most 0.

05.

82. The process according to any of the preceding claims, wherein the first time interval lasts at least 5 hours, preferably at least 6 hours, more preferably at least 7 hours, still more preferably at least 8 hours, yet more preferably at least 9 hours, even more preferably at least 10 hours, most prefer- ably at least 12 hours, and in particular at least 15 hours.

83. The process according to any of the preceding claims, wherein the first time interval lasts at most 60 hours, preferably at most 55 hours, more preferably at most 45 hours, still more preferably at most 40 hours, yet more preferably at most 35 hours, even more preferably at most 30 hours, most preferably at most 25 hours, and in particular at most 20 hours.

84. The process according to any of the preceding claims, wherein the first time interval lasts at most 18 hours, more preferably at most 17 hours, still more preferably at most 16 hours, yet more preferably at most 15 hours, even more preferably at most 14 hours, most preferably at most 13 hours, and in particular at most 12 hours.

85. The process according to any of the preceding claims, wherein the first time interval lasts 10 to 60 hours.

86. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1 is below B0 (B1 < B0).

87. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1 is at least 75.2 °Bx, preferably at least 75.4 °Bx, more preferably at least 75.6 °Bx, and still more preferably at least 75.8 °Bx.

88. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1is at least 76.0 °Bx, preferably at least 76.2 °Bx, more preferably at least 76.4 °Bx, still more preferably at least 76.6 °Bx, yet more preferably at least 76.8 °Bx, even more preferably at least 77.0 °Bx, most preferably at least 77.2 °Bx, and in par- ticular at least 77.4 °Bx.

89. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1is at least 77.6 °Bx, preferably at least 77.8 °Bx, morepreferably at least 78.0 °Bx, still more preferably at least 78.2 °Bx, yet more preferably at least 78.4 °Bx, even more preferably at least 78.6 °Bx, most preferably at least 78.8 °Bx, and in par- ticular at least 79.0 °Bx.

90. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1 is at least 79.2 °Bx, preferably at least 79.4 °Bx, more preferably at least 79.6 °Bx, still more preferably at least 79.8 °Bx, yet more preferably at least 80.0 °Bx, even more preferably at least 80.2 °Bx, most preferably at least 80.4 °Bx, and in par- ticular at least 80.6 °Bx.

91. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1 is at least 80.8 °Bx, preferably at least 81.0 °Bx, more preferably at least 81.2 °Bx, still more preferably at least 81.4 °Bx, yet more preferably at least 81.6 °Bx, even more preferably at least 81.8 °Bx, most preferably at least 82.0 °Bx, and in par- ticular at least 82.2 °Bx.

92. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1 is at least 82.4 °Bx, preferably at least 82.6 °Bx, more preferably at least 82.8 °Bx, still more preferably at least 83.0 °Bx, yet more preferably at least 83.2 °Bx, even more preferably at least 83.4 °Bx, most preferably at least 83.6 °Bx, and in par- ticular at least 83.8 °Bx.

93. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1 is at least 84.0 °Bx, preferably at least 84.2 °Bx, more preferably at least 84.4 °Bx, still more preferably at least 84.6 °Bx, yet more preferably at least 84.8 °Bx, even more preferably at least 85.0 °Bx, most preferably at least 85.2 °Bx, and in par- ticular at least 85.4 °Bx.

94. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1 is at most 88.0 °Bx, preferably at most 87.8 °Bx, more preferably at most 87.6 °Bx, still more preferably at most 87.4 °Bx, yet more preferably at most 87.2 °Bx, even more preferably at most 87.0 °Bx, most preferably at most 86.8 °Bx, and in par- ticular at most 86.6 °Bx.

95. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1is within the range of from 78.0 to 84.0 °Bx.

96. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1is below B0(B1< B0), wherein the difference B0- B1is at least 0.1 °Bx, preferably is at least 0.2 °Bx, more preferably is at least 0.3 °Bx, still morepreferably is at least 0.4 °Bx, yet more preferably is at least 0.5 °Bx, even more preferably is at least 0.6 °Bx, most preferably is at least 0.7 °Bx, and in particular is at least 0.8 °Bx.

97. The process according to any of the preceding claims, wherein at the end of the first time interval the Brix value of the mother liquor B1 is below B0 (B1 < B0), wherein the difference B0 - B1 is at most 2.0 °Bx, preferably is at most 1.9 °Bx, more preferably is at most 1.8 °Bx, still more prefer- ably is at most 1.7 °Bx, yet more preferably is at most 1.6 °Bx, even more preferably is at most 1.5 °Bx, most preferably is at most 1.4 °Bx, and in particular is at most 1.3 °Bx.

98. The process according to any of the preceding claims, wherein at the end of the first time interval the allulose purity of the mother liquor p1 is quantified, preferably by analysis, more preferably by HPLC.

99. The process according to any of the preceding claims, wherein at the end of the first time interval the allulose purity of the mother liquor p1 is quantified on the basis of the allulose purity p0 of the mother liquor provided in step (a) and on the basis of the predetermined quantity q1 of crystallized allulose.

100. The process according to any of the preceding claims, wherein at the end of the first time interval the allulose purity of the mother liquor p1 is at least 72.5 wt.-%, preferably at least 75 wt.-%, more preferably at least 78.5 wt.-%, still more preferably at least 80 wt.-%, yet more preferably at least 82.5 wt.-%, even more preferably at least 85 wt.-%, most preferably at least 87.5 wt.-%, and in particular at least 90 wt.-%, relative to the total dry solids content of the mother liquor.

101. The process according to any of the preceding claims, wherein at the end of the first time interval the allulose purity of the mother liquor p1 is at most 99.0 wt.-%, preferably at most 98.0 wt.-%, more preferably at most 97.0 wt.-%, still more preferably at most 96.0 wt.-%, yet more preferably at most 95.0 wt.-%, even more preferably at most 94.0 wt.-%, most preferably at most 93.0 wt.- %, and in particular at most 92.0 wt.-%, relative to the total dry solids content of the mother liquor.

102. The process according to any of the preceding claims, wherein at the end of the first time interval the allulose purity of the mother liquor p1is within the range of from 80 to 100%, relative to the total dry solids content of the mother liquor.

103. The process according to any of the preceding claims, wherein at the end of the first time interval the difference p0- p1is at least 0.05 wt.-%, preferably at least 0.1 wt.-%, more preferably at least 0.2 wt.-%, still more preferably at least 0.3 wt.-%, yet more preferably at least 0.4 wt.-%, even more preferably at least 0.5 wt.-%, most preferably at least 0.5 wt.-%, and in particular at least 0.7 wt.-%.

104. The process according to any of the preceding claims, wherein the temperature during step (b) (first time interval) is controlled, preferably closed-loop controlled, and kept essentially constant in order to maintain substantially isothermal conditions.

105. The process according to any of the preceding claims, wherein in step (b) the mother liquor is agitated, preferably by stirring.

106. The process according to claim 105, wherein the energy dissipation rate by stirring in step (b) is at most 800 W·m-3, preferably at most 700 W·m-3, more preferably at most 600 W·m-3, still more preferably at most 500 W·m-3, yet more preferably at most 400 W·m-3, even more preferably at most 300 W·m-3, most preferably at most 200 W·m-3, and in particular at most 100 W·m-3.

107. The process according to claim 105 or 106, wherein the energy dissipation rate by stirring in step (b) is at most 90 W·m-3, preferably at most 80 W·m-3, more preferably at most 70 W·m-3, still more preferably at most 60 W·m-3, yet more preferably at most 50 W·m-3, even more preferably at most 40 W·m-3, most preferably at most 35 W·m-3, and in particular at most 30 W·m-3.

108. The process according to any of the preceding claims, wherein step (c) is performed batchwise.

109. The process according to any of claims 1 to 107, wherein step (c) is performed semi-batchwise or continuously.

110. The process according to any of the preceding claims, wherein step (b) is performed in an iso- thermal crystallizer and step (c) is performed in a cooling crystallizer that is separate from the isothermal crystallizer.

111. The process according to claim 110, wherein step (b) involves at the end of the first time interval transferring the suspension that is contained in the isothermal crystallizer into the cooling crys- tallizer.

112. The process according to any of the preceding claims, wherein step (b) is performed in an iso- thermal crystallizer and step (c) is performed in a plurality of cooling crystallizers, preferably 2, 3, 4, 5 or more cooling crystallizers, that are separate from the isothermal crystallizer.

113. The process according to claim 112, wherein step (b) involves at the end of the first time interval transferring the suspension that is contained in the isothermal crystallizer into the plurality of cooling crystallizers, preferably in equal fractions.

114. The process according to any of the preceding claims, wherein step (c) involves mixing the prod- uct obtained in step (b), preferably the suspension, with another mother liquor.

115. The process according to claim 114, wherein the another mother liquor is fresh mother liquor, centrifuge discharge or any mixture thereof; preferably a mixture of fresh mother liquor withcentrifuge discharge in any mixing ratio, more preferably within the range from 90:10 to 10:90, more preferably 80:20 to 20:80, still more preferably 70:30 to 30:70, yet more preferably 65:35 to 35:65, even more preferably 60:40 to 40:60, most preferably 55:45 to 45:55, and in particular about 50:50 (v / v).

116. The process according to claim 114 or 115, wherein the volume and / or mass of the product ob- tained in step (b), preferably the suspension, is greater than the volume and / or mass of the another mother liquor.

117. The process according to claim 114 or 115, wherein the volume and / or mass of the another mother liquor is greater than the volume and / or mass of the product obtained in step (b), preferably the suspension.

118. The process according to any of the preceding claims, wherein step (c) is performed until a pre- determined quantity q2 of allulose has been crystallized from the mother liquor.

119. The process according to any of the preceding claims, wherein the quantity of allulose crystallized from the mother liquor during the second time interval is greater than the quantity of allulose crystallized from the mother liquor during the first time interval (q2 - q1 > q1).

120. The process according to claim 118 or 119, wherein the predetermined quantity q2 of crystallized allulose is at least 25 wt.-%, preferably at least 27.5 wt.-%, more preferably at least 30 wt.-%, still more preferably at least 32.5 wt.-%, yet more preferably at least 35 wt.-%, even more preferably at least 37.5 wt.-%, most preferably at least 40 wt.-%, and in particular at least 42.5 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

121. The process according to any of claim 118 to 120, wherein the predetermined quantity q2 of crys- tallized allulose is at most 67.5 wt.-%, preferably at most 65 wt.-%, more preferably at most 62.5 wt.-%, still more preferably at most 60 wt.-%, yet more preferably at most 57.5 wt.-%, even more preferably at most 55 wt.-%, most preferably at most 52.5 wt.-%, and in particular at most 50 wt.- %, relative to the total weight of the mother liquor provided in step (a) m0.

122. The process according to any of claims 118 to 121, wherein the predetermined quantity q2 of crystallized allulose is within the range of 25 to 55 wt.-%, preferably 30 to 50 wt.-%, relative to the total weight of the mother liquor provided in step (a) m0.

123. The process according to any of the preceding claims, wherein the second time interval immedi- ately follows the first time interval.

124. The process according to any of the preceding claims, wherein the second time interval lasts at least 10 hours, preferably at least 12 hours, more preferably at least 14 hours, still more preferablyat least 16 hours, yet more preferably at least 18 hours, even more preferably at least 20 hours, most preferably at least 22 hours, and in particular at least 24 hours.

125. The process according to any of the preceding claims, wherein the second time interval lasts at most 80 hours, preferably at most 75 hours, more preferably at most 70 hours, still more preferably at most 65 hours, yet more preferably at most 60 hours, even more preferably at most 55 hours, most preferably at most 50 hours, and in particular at most 45 hours.

126. The process according to any of the preceding claims, wherein the second time interval lasts at most 40 hours, preferably at most 35 hours, more preferably at most 30 hours, still more preferably at most 25 hours, yet more preferably at most 20 hours, even more preferably at most 15 hours, most preferably at most 12 hours, and in particular at most 10 hours.

127. The process according to any of the preceding claims, wherein the second time interval lasts 10 to 80 hours.

128. The process according to any of the preceding claims, wherein the second time interval is longer than the first time interval.

129. The process according to any of claims 1 to 127, wherein the first time interval is longer than the second time interval.

130. The process according to any of the preceding claims, wherein the second time interval immedi- ately follows the first time interval, and wherein the first time interval and the second time interval together last at most 80 hours, preferably at most 75 hours, more preferably at most 70 hours, still more preferably at most 65 hours, yet more preferably at most 60 hours, even more preferably at most 55 hours, most preferably at most 50 hours, and in particular at most 45 hours.

131. The process according to any of the preceding claims, wherein the second time interval immedi- ately follows the first time interval, and wherein the first time interval and the second time interval together last at most 40 hours, preferably at most 38 hours, more preferably at most 36 hours, still more preferably at most 34 hours, yet more preferably at most 32 hours, even more preferably at most 30 hours, most preferably at most 27.5 hours, and in particular at most 25 hours.

132. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2is below the Brix value of the mother liquor at the end of the first time interval B1(B2< B1).

133. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2is at least 68.0 °Bx, preferably at least 68.2 °Bx, more preferably at least 68.4 °Bx, still more preferably at least 68.6 °Bx, yet more preferably atleast 68.8 °Bx, even more preferably at least 69.0 °Bx, most preferably at least 69.2 °Bx, and in particular at least 69.4 °Bx.

134. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at least 69.6 °Bx, preferably at least 69.8 °Bx, more preferably at least 70.0 °Bx, still more preferably at least 70.2 °Bx, yet more preferably at least 70.4 °Bx, even more preferably at least 70.6 °Bx, most preferably at least 70.8 °Bx, and in particular at least 71.0 °Bx.

135. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at least 71.2 °Bx, preferably at least 71.4 °Bx, more preferably at least 71.6 °Bx, still more preferably at least 71.8 °Bx, yet more preferably at least 72.0 °Bx, even more preferably at least 72.2 °Bx, most preferably at least 72.4 °Bx, and in particular at least 72.6 °Bx.

136. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at least 72.8 °Bx, preferably at least 73.0 °Bx, more preferably at least 73.2 °Bx, still more preferably at least 73.4 °Bx, yet more preferably at least 73.6 °Bx, even more preferably at least 73.8 °Bx, most preferably at least 74.0 °Bx, and in particular at least 74.2 °Bx.

137. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at least 74.4 °Bx, preferably at least 74.6 °Bx, more preferably at least 74.8 °Bx, still more preferably at least 75.0 °Bx, yet more preferably at least 75.2 °Bx, even more preferably at least 75.4 °Bx, most preferably at least 75.6 °Bx, and in particular at least 75.8 °Bx.

138. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at least 76.0 °Bx, preferably at least 76.2 °Bx, more preferably at least 76.4 °Bx, still more preferably at least 76.6 °Bx, yet more preferably at least 76.8 °Bx, even more preferably at least 77.0 °Bx, most preferably at least 77.2 °Bx, and in particular at least 77.4 °Bx.

139. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2is at least 77.6 °Bx, preferably at least 77.8 °Bx, more preferably at least 78.0 °Bx, still more preferably at least 78.2 °Bx, yet more preferably at least 78.4 °Bx, even more preferably at least 78.6 °Bx, most preferably at least 78.8 °Bx, and in particular at least 79.0 °Bx.

140. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2is at least 79.2 °Bx, preferably at least 79.4 °Bx,more preferably at least 79.6 °Bx, still more preferably at least 79.8 °Bx, yet more preferably at least 80.0 °Bx, even more preferably at least 80.2 °Bx, most preferably at least 80.4 °Bx, and in particular at least 80.6 °Bx.

141. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at least 80.8 °Bx, preferably at least 81.0 °Bx, more preferably at least 81.2 °Bx, still more preferably at least 81.4 °Bx, yet more preferably at least 81.6 °Bx, even more preferably at least 81.8 °Bx, most preferably at least 82.0 °Bx, and in particular at least 82.2 °Bx.

142. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at least 82.4 °Bx, preferably at least 82.6 °Bx, more preferably at least 82.8 °Bx, still more preferably at least 83.0 °Bx, yet more preferably at least 83.2 °Bx, even more preferably at least 83.4 °Bx, most preferably at least 83.6 °Bx, and in particular at least 83.8 °Bx.

143. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at least 84.0 °Bx, preferably at least 84.2 °Bx, more preferably at least 84.4 °Bx, still more preferably at least 84.6 °Bx, yet more preferably at least 84.8 °Bx, even more preferably at least 85.0 °Bx, most preferably at least 85.2 °Bx, and in particular at least 85.4 °Bx.

144. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is at most 88.0 °Bx, preferably at most 87.8 °Bx, more preferably at most 87.6 °Bx, still more preferably at most 87.4 °Bx, yet more preferably at most 87.2 °Bx, even more preferably at most 87.0 °Bx, most preferably at most 86.8 °Bx, and in particular at most 86.6 °Bx.

145. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2 is within the range of from 68.0 to 78.0 °Bx.

146. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2is below the Brix value of the mother liquor at the end of the first time interval B1(B2< B1), wherein the difference B1- B2is at least 0.1 °Bx, preferably is at least 0.2 °Bx, more preferably is at least 0.3 °Bx, still more preferably is at least 0.4 °Bx, yet more preferably is at least 0.5 °Bx, even more preferably is at least 0.6 °Bx, most preferably is at least 0.7 °Bx, and in particular is at least 0.8 °Bx.

147. The process according to any of the preceding claims, wherein at the end of the second time interval the Brix value of the mother liquor B2is below the Brix value of the mother liquor at the end of the first time interval B1(B2< B1), wherein the difference B1- B2is at most 2.0 °Bx,preferably is at most 1.9 °Bx, more preferably is at most 1.8 °Bx, still more preferably is at most 1.7 °Bx, yet more preferably is at most 1.6 °Bx, even more preferably is at most 1.5 °Bx, most preferably is at most 1.4 °Bx, and in particular is at most 1.3 °Bx.

148. The process according to any of the preceding claims, wherein at the end of the second time interval the allulose purity of the mother liquor p2 is at least 62.5 wt.-%, preferably at least 65 wt.-%, more preferably at least 67.5 wt.-%, still more preferably at least 70 wt.-%, yet more pref- erably at least 72.5 wt.-%, even more preferably at least 75 wt.-%, most preferably at least 77.5 wt.-%, and in particular at least 80 wt.-%, relative to the total dry solids content of the mother liquor.

149. The process according to any of the preceding claims, wherein at the end of the second time interval the allulose purity of the mother liquor p2 is at most 99.0 wt.-%, preferably at most 98.0 wt.-%, more preferably at most 97.0 wt.-%, still more preferably at most 96.0 wt.-%, yet more preferably at most 95.0 wt.-%, even more preferably at most 94.0 wt.-%, most preferably at most 93.0 wt.-%, and in particular at most 92.0 wt.-%, relative to the total dry solids content of the mother liquor.

150. The process according to any of the preceding claims, wherein at the end of the second time interval the allulose purity of the mother liquor p2 is within the range of from 70 to 100 wt.-%, relative to the total dry solids content of the mother liquor.

151. The process according to any of the preceding claims, wherein at the end of the second time interval the difference p1 - p2 is at least 0.5 wt.-%, preferably at least 1.0 wt.-%, more preferably at least 1.5 wt.-%, still more preferably at least 2.0 wt.-%, yet more preferably at least 2.5 wt.-%, even more preferably at least 3.0 wt.-%, most preferably at least 3.5 wt.-%, and in particular at least 4.0 wt.-%.

152. The process according to any of the preceding claims, wherein at the end of the second time interval the difference p0 - p2 is at least 4.5 wt.-%, preferably at least 5.0 wt.-%, more preferably at least 5.5 wt.-%, still more preferably at least 6.0 wt.-%, yet more preferably at least 6.5 wt.-%, even more preferably at least 7.0 wt.-%, most preferably at least 7.5 wt.-%, and in particular at least 8.0 wt.-%.

153. The process according to any of the preceding claims, wherein in step (c) the mother liquor is agitated, preferably by stirring.

154. The process according to claim 153, wherein the energy dissipation rate by stirring in step (c) is at most 800 W·m-3, preferably at most 700 W·m-3, more preferably at most 600 W·m-3, still more preferably at most 500 W·m-3, yet more preferably at most 400 W·m-3, even more preferably at most 300 W·m-3, most preferably at most 200 W·m-3, and in particular at most 100 W·m-3.

155. The process according to claim 153 or 154, wherein the energy dissipation rate by stirring in step (c) is at most 90 W·m-3, preferably at most 80 W·m-3, more preferably at most 70 W·m-3, still more preferably at most 60 W·m-3, yet more preferably at most 50 W·m-3, even more preferably at most 40 W·m-3, most preferably at most 35 W·m-3, and in particular at most 30 W·m-3.

156. The process according to any of the preceding claims, wherein step (c) involves determining the quantity of allulose that has been crystallized from the mother liquor at a time point t within the second time interval.

157. The process according to claim 156, wherein the quantity of allulose that has been crystallized is determined on the basis of refractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor at the time point t, i.e. B(t); preferably Brix value.

158. The process according to claim 156 or 157, wherein the quantity of allulose that has been crystal- lized is determined by weighing precipitated solid.

159. The process according to any of the preceding claims, wherein step (c) involves cooling the tem- perature of the mother liquor.

160. The process according to claim 159, wherein cooling the temperature of the mother liquor is per- formed at a cooling rate with in the range of from 0.1 to 2.0°C / h.

161. The process according to any of the preceding claims, wherein step (c) involves measuring the temperature of the mother liquor at the time point t, i.e. T(t); preferably continuously, more pref- erably by an online measurement.

162. The process according to any of the preceding claims, wherein step (c) involves measuring the Brix value of the mother liquor at the time point t, i.e. B(t); preferably continuously, more pref- erably by an online measurement.

163. The process according to any of the preceding claims, wherein step (c) involves determining the supersaturation ratio at the time point t; preferably continuously.

164. The process according to any of the preceding claims, wherein step (c) involves measuring or determining allulose purity at the time point t, i.e. p(t); preferably continuously, more preferably by an online measurement.

165. The process according to any of the preceding claims, wherein step (c) involves controlling the temperature of the mother liquor, preferably closed-loop controlling said temperature.

166. The process according to claim 165, wherein the temperature of the mother liquor is controlled automatically, preferably closed-loop controlled automatically.

167. The process according to claim 165 or 166, wherein the temperature during step (c) (second time interval) is actively adjusted as a function of one or more measured parameters, preferably in- cluding p0and B(t).

168. The process according to any of claims 165 to 167, wherein the temperature of the mother liquor is controlled, preferably closed-loop controlled in dependence of B(t), i.e. the Brix value of the mother liquor at the time point t in °Bx, and p(t), i.e. the allulose purity in the mother liquor p(t) at a time point t.

169. The process according to any of the preceding claims, wherein during the second time interval the temperature of the mother liquor is adjusted to maintain supersaturation ratio of allulose; pref- erably wherein the supersaturation ratio of allulose is within the range of from 1.03 to 1.06, more preferably 1.04 to 1.

06.

170. The process according to any of the preceding claims, wherein at any point in time during the second time interval of step (c), the mother liquor is supersaturated; preferably wherein the su- persaturation ratio is at least 1.

01.

171. The process according to claim 170, wherein at any point in time during the second time interval of step (c), the supersaturation ratio of allulose is at least 1.025, more preferably at least 1.030, still more preferably at least 1.035, yet more preferably at least 1.040, even more preferably at least 1.045, most preferably at least 1.050, and in particular at least 1.

055.

172. The process according to claim 170 or 171, wherein at any point in time during the second time interval of step (c), the supersaturation ratio of allulose is at most 1.085, more preferably at most 1.080, still more preferably at most 1.075, yet more preferably at most 1.070, even more prefera- bly at most 1.065, most preferably at most 1.060, and in particular at most 1.

055.

173. The process according to any of claims 170 to 172, wherein during the second time interval of step (c) the supersaturation ratio of allulose in the mother liquor is determined - in knowledge of initial allulose purity p0 of the mother liquor provided in step (a); - in knowledge of initial Brix value B0of the mother liquor provided in step (a); - preferably in knowledge of allulose purity p1of the mother liquor at the end of the first time interval in step (b); - preferably in knowledge of Brix value B1of the mother liquor at the end of the first time interval in step (b); - by measuring Brix value B(t) of the mother liquor during the second time interval of step (c); - by measuring temperature T(t) of the mother liquor during the second time interval of step (c); - by determining allulose purity p(t) in the mother liquor during the second time interval of step (c) from the measured values for p0, B0,and B(t);- by determining allulose concentration in the mother liquor during the second time interval of step (c) from the measured values for p0, B0, and B(t); and - by determining allulose solubility at the determined purity p(t) and at the measured tempera- ture T(t) from calibration curves that have been measured with mother liquors of known allu- lose concentration and known allulose purity.

174. The process according to any of the preceding claims, wherein at any point in time during the second time interval of step (c), the temperature of the mother liquor is steadily decreased.

175. The process according to any of claims 169 to 174, wherein supersaturation ratio of allulose is determined by measuring refractive index, Brix value, IR spectroscopy or Raman spectroscopy of the mother liquor; preferably Brix value.

176. The process according to any of the preceding claims, wherein step (c) involves determining the allulose purity in the mother liquor p(t) at a time point t within the second time interval.

177. The process according to claim 176, wherein p(t) is defined by formula (6)∙100(6) wherein m0 is the total weight of the mother liquor provided in step (a) in kg, B0 is the Brix value of the mother liquor provided in step (a) in °Bx, p0 is the allulose purity of the mother liquor provided in step (a) in percentage points, and B(t) is the Brix value of the mother liquor at the time point t in °Bx.

178. The process according to claim 176 or 177, wherein step (c) involves the substeps (c1) determining the Brix value of the mother liquor B(t) at the time point t; (c2) determining a critical Brix value of the mother liquor B(t)cr at the time point t which is defined by formula (7): ^^(^^)^^^^ = 53.71 + 0.399 ∙ ^^(^^) + 0.375 ∙ ^^(^^) − 0.001551 ∙ ^^(^^)2 − 0.003302 ∙ ^^(^^)2 + 0.001185 ∙ ^^(^^)∙ ^^(^^)(7)wherein T(t) is the given temperature of the mother liquor at the time point t in °C; and p(t) is the given allulose purity of the mother liquor at the time point t in percentage points; (c3) deter- mining the ratio B(t) / B(t)crand comparing it with a predetermined threshold H value; when the ratio B(t) / B(t)cr deviates from the predetermined threshold H value: (c4) determining a target tem- perature of the mother liquor Ttarget, which is defined by formula (8) ^^ = −7.1 − 0.763 ∙ ^^(^^)− 1.031 ∙ ^^(^^) + 0.02166 ∙ ( ^^(^^)2 +0.00821 ∙ ^^(^^)2^^^^^^^^^^^^) ^^ ^^ (8) wherein B(t) is the given Brix value of the mother liquor B(t) at the time point t; H is the prede- termined threshold value; and p(t) is the given allulose purity of the mother liquor at the time point t; and (c5) adjusting the temperature of the mother liquor to Ttarget.

179. The process according to claim 178, wherein the predetermined threshold value H is within the range of 1.03 to 1.06, preferably 1.04 to 1.

06.

180. The process according to claim 178 or 179, wherein in substep (c5) the temperature of the mother liquor is adjusted at a rate within the range of from ±0.1 to ±2.0°C / h.

181. The process according to any of the preceding claims, wherein at the end of the second time interval the temperature of the mother liquor T2, wherein the difference T0- T2is at least 2.5°C, preferably at least 5.0°C, more preferably at least 7.5°C, still more preferably at least 10°C, yet more preferably at least 12.5°C, even more preferably at least 15°C, most preferably at least 17.5°C, and in particular at least 20°C.

182. The process according to any of the preceding claims, wherein at the end of the second time interval the temperature of the mother liquor T2is at least 3.0°C, preferably at least 4.0°C, more preferably at least 5.0°C, still more preferably at least 6.0°C, yet more preferably at least 7.0°C, even more preferably at least 8.0°C, most preferably at least 9.0°C, and in particular at least 10°C.

183. The process according to any of the preceding claims, wherein at the end of the second time interval the temperature of the mother liquor T2is at most 42°C, preferably at most 41°C, more preferably at most 40°C, still more preferably at most 39°C, yet more preferably at most 38°C, even more preferably at most 37°C, most preferably at most 36°C, and in particular at most 35°C.

184. The process according to any of the preceding claims, wherein at the end of the second time interval the temperature of the mother liquor T2is within the range of from 10 to 35°C.

185. The process according to any of the preceding claims, wherein the viscosity of the magma is at most 50 Pa·s, preferably at most 45 Pa·s, more preferably at most 40 Pa·s, still more preferablyat most 35 Pa·s, yet more preferably at most 30 Pa·s, even more preferably at most 29 Pa·s, most preferably at most 28 Pa·s, and in particular at most 27 Pa·s, at any point in time during the process.

186. The process according to any of the preceding claims, wherein the color of the liquid phase is at most 15,000, preferably at most 14,000 IU, more preferably at most 13,000 IU, still more prefer- ably at most 12,000 IU, yet more preferably at most 11,000 IU, even more preferably at most 10,000 IU, most preferably at most 9,000 IU, and in particular at most 8,000 IU, at any point in time during the process.

187. The process according to any of the preceding claims, which does not involve evaporation crys- tallization.

188. The process according to any of the preceding claims, which does not involve ethanol, preferably not any organic solvents.

189. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a total content of impurities of at most 3.0 wt.-%, preferably at most 2.5 wt.-%, more preferably at most 2.0 wt.-%, still more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, and even more preferably at most 0.8 wt.-% of the total dry solids content of the mother liquor provided in step (a).

190. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a total content of impurities of at most 0.6 wt.-%, preferably at most 0.5 wt.-%, more preferably at most 0.4 wt.-%, still more preferably at most 0.3 wt.-%, yet more preferably at most 0.2 wt.-%, and even more preferably at most 0.1 wt.-% of the total dry solids content of the mother liquor provided in step (a).

191. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) contains one or more impurities selected from allulose dimer, allulose-fructose disaccharide, allulose-glucose disaccharide, allulose tetramer, diallulose anhydride, levulinic acid, γ-hydroxy valeric acid (GVA), furfural, hydroxymethyl furfural (HMF), 2,5-dimethylfurane, 2,5-furane di- carboxylic acid (FDCA), 5-hydroxymethyl furane 2-carboxylic acid, 2,5-formyl furane carbox- ylic acid, 2,5-furane dialdehyde, 2,5-bis-(hydroxy-methyl)furane, bis(5-formyl-2-furfuryl)ether), furane-2-carboxylic acid, furane-3-carboxylic acid, 5-hydroxyfurfural, 2,5-dihydro-2,5-di- methoxyfurane, (2R)-5-oxotetrahydro-2-furane carboxylic acid, bis(5-methyl furfuryl)ether, 5,5ʹ- methylene-di(furane-2-carboxylic acid), or any combination thereof.

192. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) contains one or more impurities selected from lactic acid, maltol, furaneol, allosone,glucosone, 1-desoxyglucosone, 3-desoxyglucosone, 3-desoxygalactosone, formic acid, acetic acid, propionic acid, glyoxal, or any combination thereof.

193. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) contains one or more impurities selected from 2,3-butanedione, acetaldehyde, 2-keto-D-glu- cose (glucosone), 3-desoxyglucosone, or any combination thereof.

194. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of hydroxymethyl furfural (HMF) within the range of 1 to 10,000 ppmw, pref- erably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor.

195. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of hydroxymethyl furfural (HMF) of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

196. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of 2,3-butanedione within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more pref- erably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor.

197. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of 2,3-butanedione of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

198. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of acetaldehyde within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more pref- erably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor.

199. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of acetaldehyde of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably atmost 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

200. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of 2-keto-D-glucose within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more pref- erably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor.

201. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of 2-keto-D-glucose of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

202. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of allosone within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor.

203. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of allosone of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

204. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of 3-desoxyglucosone within the range of 1 to 10,000 ppmw, preferably 1 to 8,000 ppmw, more preferably 1 to 6,000 ppmw, yet more preferably 1 to 4,000 ppmw, even more preferably 1 to 2,000 ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the mother liquor.

205. The process according to any of the preceding claims, wherein the mother liquor provided in step (a) has a content of 3-desoxyglucosone of at most 1000 ppmw, preferably at most 800 ppmw, more preferably at most 600 ppmw, yet more preferably at most 400 ppmw, even more preferably at most 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the mother liquor.

206. The process according to any of the preceding claims, wherein step (b) is performed under non- evaporative conditions, preferably at atmospheric pressure.

207. The process according to any of the preceding claims, wherein step (c) is performed under non- evaporative conditions, preferably at atmospheric pressure.

208. A crystalline allulose that is characterized by an x-ray diffractogram determined at 23°C with Cu kα radiation within the range of from about 12.8 to about 76.5 °2θ comprising - a first x-ray reflection with the greatest intensity of all x-ray reflections and - a second x-ray reflection with the second greatest intensity of all x-ray reflections, wherein the first x-ray reflection or the second x-ray reflection is at 31.0±0.1 °2θ.

209. The crystalline allulose according to claim 208, wherein the first x-ray reflection is at one of 15.4±0.1 and 31.0±0.1 °2θ, and wherein the second x-ray reflection is at the other one of 15.4±0.1 and 31.0±0.1 °2θ.

210. The crystalline allulose according to claim 208 or 209, wherein the first x-ray reflection is at 15.4±0.1 °2θ.

211. The crystalline allulose according to any of claims 208 to 210, wherein the second x-ray reflection is at 31.0±0.1 °2θ.

212. The crystalline allulose according to any of claims 208 to 211, wherein the x-ray diffractogram comprises - a third x-ray reflection having the third greatest intensity of all x-ray reflections and - a fourth x-ray reflection having the fourth greatest intensity of all x-ray reflections, wherein the third x-ray reflection or the third x-ray reflection is at 47.2±0.1 °2θ.

213. The crystalline allulose according to claim 212, wherein the third x-ray reflection is at 47.2±0.1 °2θ.

214. The crystalline allulose according to any of claims 208 to 213, which has a particle size distribu- tion with a value for X50,r determined by dynamic image analysis according to ISO 13322-2 of at least 50 µm, preferably at least 60 µm, more preferably at least 65 µm, still more preferably at least 70 µm, yet more preferably at least 75 µm, even more preferably at least 80 µm, most pref- erably at least 85 µm, and in particular at least 90 µm.

215. The crystalline allulose according to any of claims 208 to 214, which has a particle size distribu- tion with a value for X50,rdetermined by dynamic image analysis according to ISO 13322-2 of at most 600 µm, preferably at most 550 µm, more preferably at most 500 µm, still more preferably at most 450 µm, yet more preferably at most 400 µm, even more preferably at most 350 µm, most preferably at most 300 µm, and in particular at most 250 µm.

216. The crystalline allulose according to any of claims 208 to 215, which has a particle size distribu- tion with a value for X50,rdetermined by dynamic image analysis according to ISO 13322-2 withinthe range of 200±180 µm, preferably 200±160 µm, more preferably 200±140 µm, still more pref- erably 200±120 µm, yet more preferably 200±100 µm, even more preferably 200±80 µm, most preferably 200±60 µm, and in particular 200±40 µm.

217. The crystalline allulose according to any of claims 208 to 215, which has a particle size distribu- tion with a value for X50,r determined by dynamic image analysis according to ISO 13322-2 within the range of 300±180 µm, preferably 300±160 µm, more preferably 300±140 µm, still more pref- erably 300±120 µm, yet more preferably 300±100 µm, even more preferably 300±80 µm, most preferably 300±60 µm, and in particular 300±40 µm.

218. The crystalline allulose according to any of claims 208 to 215, which has a particle size distribu- tion with a value for X50,r determined by dynamic image analysis according to ISO 13322-2 within the range of 400±180 µm, preferably 400±160 µm, more preferably 400±140 µm, still more pref- erably 400±120 µm, yet more preferably 400±100 µm, even more preferably 400±80 µm, most preferably 400±60 µm, and in particular 400±40 µm.

219. The crystalline allulose according to any of claims 208 to 218, which has a particle size distribu- tion with a value for X10,r determined by dynamic image analysis according to ISO 13322-2, pref- erably with a dispersion pressure of 20 kPa, of at least 50 µm, preferably at least 60 µm, more preferably at least 65 µm, still more preferably at least 70 µm, yet more preferably at least 75 µm, even more preferably at least 80 µm, most preferably at least 85 µm, and in particular at least 90 µm.

220. The crystalline allulose according to any of claims 208 to 219, which has a particle size distribu- tion with a value for X10,r determined by dynamic image analysis according to ISO 13322-2, pref- erably with a dispersion pressure of 20 kPa, of at most 600 µm, preferably at most 550 µm, more preferably at most 500 µm, still more preferably at most 450 µm, yet more preferably at most 400 µm, even more preferably at most 350 µm, most preferably at most 300 µm, and in particular at most 250 µm.

221. The crystalline allulose according to any of claims 208 to 220, which has a particle size distribu- tion with a value for X10,rdetermined by dynamic image analysis according to ISO 13322-2, pref- erably with a dispersion pressure of 20 kPa, within the range of 200±180 µm, preferably 200±160 µm, more preferably 200±140 µm, still more preferably 200±120 µm, yet more preferably 200±100 µm, even more preferably 200±80 µm, most preferably 200±60 µm, and in particular 200±40 µm.

222. The crystalline allulose according to any of claims 208 to 221, which has a particle size distribu- tion with a value for X90,rdetermined by dynamic image analysis according to ISO 13322-2, pref- erably with a dispersion pressure of 20 kPa, of at least 50 µm, preferably at least 100 µm, morepreferably at least 150 µm, still more preferably at least 200 µm, yet more preferably at least 250 µm, even more preferably at least 300 µm, most preferably at least 350 µm, and in particular at least 400 µm.

223. The crystalline allulose according to any of claims 208 to 222, which has a particle size distribu- tion with a value for X90,r determined by dynamic image analysis according to ISO 13322-2, pref- erably with a dispersion pressure of 20 kPa, of at most 1000 µm, preferably at most 950 µm, more preferably at most 900 µm, still more preferably at most 850 µm, yet more preferably at most 800 µm, even more preferably at most 750 µm, most preferably at most 700 µm, and in particular at most 650 µm.

224. The crystalline allulose according to any of claims 208 to 223, which has a particle size distribu- tion with a value for X90,r determined by dynamic image analysis according to ISO 13322-2, pref- erably with a dispersion pressure of 20 kPa, within the range of 450±225 µm, preferably 450±200 µm, more preferably 450±175 µm, still more preferably 450±150 µm, yet more preferably 450±125 µm, even more preferably 450±100 µm, most preferably 450±75 µm, and in particular 450±50 µm.

225. The crystalline allulose according to any of claims 208 to 224, which has a particle shape with a b / l value (breadth / length) determined by dynamic image analysis according to ISO 13322-2, preferably with a dispersion pressure of 20 kPa, of at least 0.20, preferably at least 0.25, more preferably at least 0.30, still more preferably at least 0.35, yet more preferably at least 0.40, even more preferably at least 0.45, most preferably at least 0.50, and in particular at least 0.

55.

226. The crystalline allulose according to any of claims 208 to 225, which has a particle shape with a b / l value (breadth / length) determined by dynamic image analysis according to ISO 13322-2, preferably with a dispersion pressure of 20 kPa, of at most 1.00, preferably at most 0.95, more preferably at most 0.90, still more preferably at most 0.85, yet more preferably at most 0.80, even more preferably at most 0.75, most preferably at most 0.70, and in particular at most 0.

65.

227. The crystalline allulose according to any of claims 208 to 226, which has a particle shape with a b / l value (breadth / length) determined by dynamic image analysis according to ISO 13322-2, preferably with a dispersion pressure of 20 kPa, within the range of 0.60±0.40, preferably 0.60±0.35, more preferably 0.60±0.30, still more preferably 0.60±0.25, yet more preferably 0.60±0.20, even more preferably 0.60±0.15, most preferably 0.60±0.10, and in particular 0.60±0.

05.

228. The crystalline allulose according to any of claims 208 to 227, which has been obtained or is obtainable by the process according to any of claims 1 to 207.

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