A highly fluid crystalline L-arabinose and its production method

Abstract

The present application discloses a highly fluid crystalline L - arabinose and its production method. The specific preparation method of the highly fluid crystalline L - arabinose includes the following steps: Treatment of xylose mother liquor: Ferment the xylose mother liquor to obtain a pretreated solution; Preparation of crystallization raw material: Separate the arabinose - fractionated liquor from the pretreated solution as the crystallization raw material; Crystallization: Perform staged cooling crystallization on the crystallization raw material at different cooling rates, and perform crystal seeding for a certain period of time after the cooling is completed to obtain the L - arabinose crystals. By the method of the present application, arabinose with coarse particles and high fluidity can be obtained, which can be used as a powder feedstock in production or for preparing powder products, and can be directly applied to products such as solid preparations and solid beverages.

Description

Technical Field

[0001] This application belongs to the field of biochemistry, relates to the production technology of L-arabinose, and in particular to a crystalline L-arabinose with high fluidity and its preparation method. Background Art

[0002] L-arabinose (C5H10O5) is a pentose aldehyde sugar, also known as L(+)-arabinose. It was initially isolated from gum arabic as a monosaccharide. Free L-arabinose rarely exists in nature. It is usually combined with other monosaccharides and exists in the form of heteropolysaccharides in gums, hemicelluloses, bacterial polysaccharides, and certain glycosides. L-arabinose is a calorie-free sweetener and is increasingly widely used in the fields of food and medicine. It can be used as a pharmaceutical intermediate, for the preparation of bacterial culture media in the biochemical field, and for spice synthesis, etc. L-arabinose products, as food sweeteners, are increasingly favored by people, and their healthcare functions such as reducing blood sugar and preventing dental caries have also been confirmed by scientific research.

[0003] Since free L-arabinose exists less in nature, it mainly relies on industrial technology for production. In actual production, how to obtain L-arabinose particles with better fluidity is crucial. For example, Patent CN 116554239 A mentions a preparation method of L-arabinose granules. Its raw material is arabinose with a purity ≥99%. It is redissolved for recrystallization, and after centrifugal drying, granules are obtained to improve fluidity. The crystallization method adopted in Patent CN 101665524 B requires sugar boiling and crystallization 2 times or more. Each crystallization requires redissolving the sugar paste centrifuged in the previous crystallization, evaporating and concentrating it, and then crystallizing again. Patent CN116444584 A discloses two methods for preparing high-purity arabinose, both using finished arabinose as the raw material, decolorizing it again after dissolving the sugar, and further processing. However, these methods all require multiple crystallizations, increasing energy consumption and having a low yield, thus reducing production efficiency. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, this application provides an improved preparation process of L-arabinose, which can obtain arabinose with thick particles and high fluidity.

[0005] The specific technical solution of this application is as follows:

[0006] This application provides a preparation method of L-arabinose, which includes the following steps:

[0007] Treatment of xylose mother liquor: Ferment the xylose mother liquor to obtain a pretreatment solution;

[0008] Preparation of crystallization raw material: Separating the arabinose fraction liquid from the pretreatment liquid as the crystallization raw material;

[0009] Crystallization: Cooling the crystallization raw material at different cooling rates in stages for crystallization, and performing crystal aging for a certain period of time after the cooling is completed to obtain the L-arabinose crystals.

[0010] Further, in the crystallization step of the preparation method, it includes cooling at different cooling rates in stages for crystallization. The staged cooling sequentially includes a first cooling stage, a second cooling stage, and a third cooling stage. In the first cooling stage, the crystallization temperature is reduced to 55 °C. In the second cooling stage, the crystallization temperature is reduced to 45 °C. In the third cooling stage, the crystallization temperature is reduced to 28 - 35 °C.

[0011] More preferably, the cooling rates of the first cooling stage, the second cooling stage, and the third cooling stage increase sequentially.

[0012] Further, the crystallization step of the preparation method also includes performing crystal aging for a certain period of time after the staged cooling crystallization, and the crystal aging time is 12 - 48 h.

[0013] More preferably, the temperature of the crystal aging is 28 - 35 °C.

[0014] More preferably, the solid content of the L-arabinose crystals after crystal aging is ≥50%.

[0015] Further, in the xylose mother liquor treatment step of the preparation method, it includes removing the miscellaneous sugars in the xylose mother liquor by fermentation.

[0016] More preferably, the miscellaneous sugars at least include glucose and galactose.

[0017] Further, the xylose mother liquor treatment step of the preparation method also includes filtering to remove the impurities in the xylose mother liquor after fermentation.

[0018] More preferably, the impurities include gels, thalli, and macromolecular pigments.

[0019] Further, the xylose mother liquor treatment step of the preparation method also includes concentrating the xylose mother liquor after fermentation.

[0020] More preferably, the sugar concentration after concentration is 45% - 55% to obtain the pretreatment liquid.

[0021] Further, the crystallization raw material preparation step of the preparation method includes obtaining the arabinose fraction liquid by chromatographic separation.

[0022] Further preferably, the arabinose content of the arabinose fraction liquor is 70% - 80%.

[0023] Furthermore, in the step of preparing the crystallization raw material of the preparation method, decolorization treatment is also included for the arabinose fraction liquor.

[0024] Further preferably, the decolorization treatment is carried out using activated carbon.

[0025] Furthermore, in the step of preparing the crystallization raw material of the preparation method, desalting treatment is also included for the arabinose fraction liquor.

[0026] Further preferably, desalting treatment is carried out by means of ion exchange, electrodialysis and / or EDI electro - desalting.

[0027] Furthermore, in the step of preparing the crystallization raw material of the preparation method, concentration treatment is also included for the separated arabinose fraction liquor.

[0028] Further preferably, the crystallization raw material with a sugar concentration of 55% - 65% is obtained after concentration.

[0029] Furthermore, in the crystallization step of the preparation method, negative - pressure concentration is also included for the crystallization raw material before crystallization.

[0030] Further preferably, the crystallization raw material is concentrated to a sugar concentration of 72% - 78% through negative - pressure concentration.

[0031] Furthermore, in the crystallization step of the preparation method, seed crystals are added to the crystallization raw material before crystallization.

[0032] Further preferably, the seed crystals are arabinose with a mesh size of 80 - 100.

[0033] Further preferably, the addition amount of the seed crystals is 0.01% - 0.05% of the mass of the crystallization raw material.

[0034] Furthermore, in the preparation method, a step of centrifugal separation is also included after crystal cultivation.

[0035] Furthermore, in the preparation method, a step of drying is also included after crystal cultivation.

[0036] Further preferably, drying is carried out after the centrifugal separation.

[0037] Further preferably, the moisture content of the L - arabinose crystals after drying is < 0.5%.

[0038] This application also provides L - arabinose prepared by the preparation method described in any one of the above.

[0039] The present application also provides an L-arabinose, wherein the L-arabinose has an angle of repose <30°, a compression degree ≤10%, and a bulk density ≥0.8 g / cm 3 , the Hausner ratio is 1.00~1.11.

[0040] The present application also provides the preparation method or the use of the L-arabinose in the preparation of a powder product. Furthermore, the powder product includes a solid beverage or a solid preparation.

[0041] Effects of the Invention

[0042] The preparation method provided in this application has the following technical effects:

[0043] (1) The prior art generally adopts two crystallizations, while the technical solution of the present application adopts one crystallization, which can effectively shorten the production process and reduce the consumption of energy such as water, electricity, and steam, thereby improving production efficiency and saving energy;

[0044] (2) Compared with traditional sugar boiling crystallization, cooling crystallization reduces the residence time of sugar solution at high temperature, reduces the occurrence of Maillard reaction, isomerization, polymerization, decomposition and other reactions, thereby inhibiting the formation of crystallization inhibitors.

[0045] (3) During the arabinose crystal precipitation stage, the cooling rate is precisely controlled in stages, so that the arabinose particles appear to be long or short under an electron microscope, and the crystal surface is smooth. This morphology has better fluidity than slender needle-shaped crystals with rough surfaces, and is not prone to secondary breakage or agglomeration.

[0046] (4) Adding crystal growing steps and adjusting the crystal growing time can further increase the size of the crystal particles, improve fluidity, and increase the crystal yield to more than 60%.

[0047] The technical solution of the present application can obtain coarse-grained, high-fluidity arabinose, which can be directly used in the compounding of solid preparations, solid beverages, etc. without granulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the process flow of a method for preparing L-arabinose provided in this application. DETAILED DESCRIPTION

[0049] The specific embodiments of the present application will be described in more detail below in conjunction with examples. It should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to enable the scope of the present application to be fully communicated to those skilled in the art.

[0050] It should be noted that the term "comprising" or "including" mentioned throughout the specification and claims is an open-ended term and should thus be construed as "including but not limited to". The subsequent description in the specification is for the preferred embodiments of implementing the present application, but such description is for the purpose of explaining the general principles of the present application and not for limiting the scope of the present application. The scope of protection of the present application shall be determined by what is defined in the appended claims.

[0051] In one aspect of the present application, a method for preparing highly fluid L-arabinose is provided, which comprises the following steps:

[0052] Treatment of xylose mother liquor: Fermenting the xylose mother liquor to obtain a pretreatment solution;

[0053] Preparation of crystallization raw material: Separating the arabinose fraction liquor from the pretreatment solution as the crystallization raw material;

[0054] Crystallization: Cooling the crystallization raw material in stages at different cooling rates and performing crystal aging for a certain period of time after the cooling is completed to obtain the L-arabinose crystals.

[0055] In a specific embodiment, the xylose mother liquor in the present application is from the xylose mother liquor of agricultural and forestry waste, and the agricultural and forestry waste includes but is not limited to: corncobs, wheat straw, beet pulp, sugarcane bagasse, crop straws, plant stems, leaves and roots, bran, corn husks, etc., and any other agricultural and forestry waste containing pentose.

[0056] In a specific embodiment, in addition to L-arabinose, the xylose mother liquor also contains xylose, xylan, L-arabinose, glucose, galactose, mannose, rhamnose, etc.

[0057] In a specific embodiment, most of the other miscellaneous sugars in the xylose mother liquor except L-arabinose are removed by fermentation.

[0058] In some specific embodiments, the miscellaneous sugars at least include hexoses such as glucose and galactose.

[0059] In some specific embodiments, glucose and galactose can be removed by conventional fermentation means. For example, for the fermentation of glucose, ordinary baker's yeast or Saccharomyces cerevisiae can be used as the nutritional carbon source of the strain to generate carbon dioxide, water or ethanol by changing conditions. For the fermentation of galactose, strains capable of utilizing galactose can be screened and the fermentation conditions can be optimized for fermentation. Miscellaneous sugars with relatively low contents such as mannose and rhamnose can generate carbon dioxide and water during the fermentation of glucose and galactose and no additional treatment steps are required.

[0060] In a specific embodiment, the above step of treating the xylose mother liquor further includes a filtration step to filter and remove impurities in the xylose mother liquor after fermentation.

[0061] In a specific embodiment, other impurity sugars in the xylose mother liquor, as well as impurities such as gels, bacterial cells, and macromolecular pigments formed during the fermentation process, can be further removed through the filtration step.

[0062] In some specific embodiments, mechanical filtration equipment and / or membrane filtration equipment are used to remove impurities in the xylose mother liquor.

[0063] In a specific embodiment, the above-mentioned xylose mother liquor treatment step further includes a concentration step. In some preferred embodiments, after the xylose mother liquor is fermented and filtered, it is then concentrated.

[0064] In some specific embodiments, a pretreatment liquid with a sugar concentration of 45% - 55% is obtained after concentration, and operations for subsequent crystallization raw material preparation are carried out.

[0065] In a specific embodiment, the crystallization raw material preparation step of the preparation method includes obtaining an arabinose fraction liquid through chromatographic separation.

[0066] In some specific embodiments, the temperature of the chromatographic separation system is set to 60°C - 65°C, and a chromatographic fraction with an arabinose content of 70% - 80% after chromatographic separation is selected.

[0067] In some specific embodiments, the arabinose content of the arabinose fraction liquid obtained through chromatographic separation is 70% - 80%.

[0068] In a specific embodiment, the crystallization raw material preparation step further includes decolorizing the arabinose fraction liquid obtained through chromatographic separation.

[0069] In some specific embodiments, the decolorization treatment is carried out using activated carbon.

[0070] In some preferred embodiments, 0.05% - 0.5% (by mass percentage) of activated carbon is added to the arabinose fraction liquid obtained through chromatographic separation, stirred at 50°C - 65°C for 30 min - 60 min, and the waste carbon is removed through plate and frame filtration to obtain a decolorized liquid.

[0071] In a specific embodiment, the crystallization raw material preparation step further includes desalting the arabinose fraction liquid.

[0072] In some specific embodiments, after the above decolorization treatment, the decolorized liquid is further desalted.

[0073] In some specific embodiments, one or more of ion exchange, electrodialysis, and EDI electro - desalting methods are used for desalting treatment.

[0074] In some specific embodiments, the desalting treatment includes first using electrodialysis or EDI for desalting, and then performing ion exchange for desalting.

[0075] In a specific embodiment, salts and residual pigments are removed through desalting treatment.

[0076] In a specific embodiment, the preparation step of the crystallization raw material further includes concentrating the separated arabinose fraction liquid.

[0077] In some specific embodiments, after the above-mentioned decolorization treatment and / or desalting treatment, a concentration treatment is performed.

[0078] In some specific embodiments, MVR or triple-effect concentration is used for the concentration treatment.

[0079] In some specific embodiments, when the sugar concentration of the liquid material is lower than 60%, a triple-effect vacuum falling film evaporator is used for concentration, and when the sugar concentration of the liquid material is higher than 60%, vacuum single-effect concentration is used.

[0080] In some specific embodiments, the crystallization raw material with a sugar concentration of 55% - 65% is obtained after concentration.

[0081] In a specific embodiment, the above-mentioned crystallization raw material, preferably the crystallization raw material that has been decolorized, desalted, and concentrated, is further subjected to the subsequent crystallization step.

[0082] In the embodiments of the present application, the crystallization step includes staged cooling crystallization at different cooling rates.

[0083] In a specific embodiment, the staged cooling is to precisely control the corresponding cooling rate in different cooling stages, so that the crystal particles change from the original slender needle shape to thick and long or thick and short shapes.

[0084] In some specific embodiments, the staged cooling process includes three cooling stages, namely the first cooling stage, the second cooling stage, and the third cooling stage in sequence.

[0085] In some specific embodiments, in the first cooling stage, the temperature is lowered at an extremely slow rate, so that the already formed fine crystal nuclei grow slowly, preventing the temperature from dropping too fast and causing nucleation explosion to form a large number of fine and fragmented crystals. In the case of extremely slow cooling, the crystals precipitated as the supersaturation increases with the decrease in temperature preferentially attach to the existing crystal nuclei and grow, and it is not easy to form new crystal nuclei, resulting in fewer and larger crystal nuclei. In the second cooling stage, the crystal nuclei have grown, and the cooling rate can be appropriately increased to induce the newly precipitated crystals to continue to attach to the existing crystal nuclei and grow further. In the third cooling stage, the cooling rate is further increased to accelerate crystal precipitation and shorten the crystal precipitation time, so as to improve production efficiency.

[0086] In some specific embodiments, during the first cooling stage, the crystallization temperature is lowered to 55 °C, during the second cooling stage, the crystallization temperature is lowered to 45 °C, and during the third cooling stage, the crystallization temperature is lowered to 28 - 35 °C.

[0087] In some preferred embodiments, the cooling rate in the first cooling stage is 0.3 °C / h - 0.5 °C / h, the cooling rate in the second cooling stage is 0.5 °C / h - 1.0 °C / h, and the crystallization temperature is lowered to 28 - 35 °C at a rate of 1.0 °C / h - 1.5 °C / h in the third cooling stage.

[0088] In specific embodiments, the preparation method further includes subjecting the crystallization raw material to negative pressure concentration before the crystallization step.

[0089] In some specific embodiments, the negative pressure concentration includes subjecting the crystallization raw material to negative pressure concentration in a sugar boiling pan at a temperature of 60 °C - 70 °C.

[0090] In some specific embodiments, the crystallization raw material is concentrated to a sugar concentration of 72% - 78% through negative pressure concentration.

[0091] In specific embodiments, the preparation method further includes adding seed crystals to the crystallization raw material before the crystallization step.

[0092] In some specific embodiments, the seed crystals are arabinose with a mesh size of 80 - 100.

[0093] In some specific embodiments, the addition amount of the seed crystals is 0.01% - 0.05% of the mass of the crystallization raw material.

[0094] In some specific embodiments, it is necessary to ensure that the seed crystals do not melt. If the seed crystals melt, additional seed crystals are appropriately added.

[0095] In some specific embodiments, the crystallization raw material after adding the seed crystals is discharged into a crystallizer for the staged cooling crystallization.

[0096] In specific embodiments, the crystallization step further includes crystal ripening after the staged cooling crystallization.

[0097] In specific embodiments, crystal ripening is carried out at a crystal ripening temperature of 28 - 35 °C (i.e., the temperature after the end of the third cooling stage).

[0098] In specific embodiments, heat preservation and stirring are carried out at the crystal ripening temperature for a duration of 12 - 48 h.

[0099] In some preferred embodiments, the solid content of L - arabinose crystals in the sugar paste obtained after crystal ripening is ≥50%.

[0100] In a specific embodiment, the preparation method further includes a step of centrifugal separation after crystal cultivation.

[0101] In some specific embodiments, the L - arabinose sugar paste obtained after crystal cultivation is subjected to centrifugal separation. During the centrifugation process, when it is observed that no mother liquor is secreted, high - purity water is intermittently sprayed for washing until the crystals in the centrifuge turn white as observed through the sight glass and the washing liquid no longer secretes, then the centrifugation is stopped.

[0102] In a specific embodiment, the preparation method further includes a step of drying after crystal cultivation.

[0103] In some specific embodiments, after crystal cultivation, the above - mentioned centrifugal separation is first carried out, and then the L - arabinose crystals obtained after centrifugal separation are dried.

[0104] In some specific embodiments, the centrifuged L - arabinose crystals are fed into a fluidized bed for staged drying.

[0105] In some preferred embodiments, the temperature of the hot - air section for staged drying is 95°C - 105°C, the temperature of the warm - air section is 50°C - 60°C, and the temperature of the cold - air section is 20°C - 25°C. By adjusting the temperature, the discharge temperature and the ambient temperature in the packaging room are controlled to be <5°C.

[0106] In some specific embodiments, the moisture content of the L - arabinose crystals obtained after drying is <0.5%.

[0107] In some embodiments, the crystal morphology is observed using a scanning electron microscope, and the fluidity index and application conditions of the crystals are detected.

[0108] This application also provides L - arabinose prepared by the preparation method described in any one of the above.

[0109] This application also provides a kind of L - arabinose, the angle of repose of the L - arabinose <30°, for example, the angle of repose is 29°, 28°, 27°, 26°, 25°, 24°, 23°, 22°, 21°, 20°; the compressibility of the L - arabinose ≤10%, for example, the compressibility is 10%, 9.5%, 9%, 8.5%, 8%, 7.5%, 7%, 6.5%, 6%, 5.5%, 5%; the bulk density of the L - arabinose ≥0.8 g / cm 3 , for example, the bulk density is 0.8 g / cm 3 , 0.75 g / cm 3 , 0.7 g / cm 3 , 0.65 g / cm 3 , 0.6 g / cm 3 , 0.55 g / cm 3, 0.5 g / cm 3 , 0.4 g / cm 3 , the Hausner ratio of the L - arabinose is 1.00 - 1.11, for example, the Hausner ratio is 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11.

[0110] The L - arabinose provided by this application is a high - fluidity crystal, which can be used as powder feeding in production or be conveniently applied in the preparation of powder products (such as solid beverages, etc.).

[0111] Examples

[0112] This application generally and / or specifically describes the materials and experimental methods used in the experiments. In the following examples, the seed crystal used is L - arabinose produced by Jinan Shengquan Tanghetao Biotechnology Co., Ltd., with a purity ≥ 99% (meeting the standard QB / T 4321 - 2012) and passing through a 80 - mesh to 100 - mesh grinding and sieving. For the rest of the reagents or instruments used, if there is no special description, they are all conventional reagents or instruments that can be obtained through commercial purchase.

[0113] Example 1

[0114] (1) Treatment of xylose mother liquor: Ferment the xylose mother liquor to obtain a pretreatment solution.

[0115] (2) Preparation of crystallization raw material: After chromatographically separating the pretreatment solution obtained in the previous step, add activated carbon accounting for 0.1% of the mass of the sugar solution to the chromatographic fraction with an arabinose content of 75.43% at 60 °C, stir for 40 min and then filter to remove the activated carbon to obtain a decolorized sugar solution. After removing salts and some residual pigments from the decolorized sugar solution through an ion - exchange system, it is concentrated to a sugar concentration of 60% as the crystallization raw material.

[0116] (3) Crystallization: The crystallization raw material obtained in the previous step is negatively pressurized and concentrated in a vacuum reaction kettle. During the concentration process, the temperature of the sugar solution is 65 °C - 67 °C, and it is concentrated to a sugar concentration of 73%. Add arabinose with a mesh size of 80 - 100 meshes accounting for 0.03% of the mass of the bottom material as the seed crystal, stir evenly and then stop concentration. Start to cool down in stages: The first stage is to cool down from 65 °C - 67 °C to 55 °C at a cooling rate of 0.3 °C / h, the second stage is to cool down from 55 °C to 45 °C at a cooling rate of 0.75 °C / h, and the third stage is to cool down from 45 °C to 30 °C at a cooling rate of 1.2 °C / h. After cooling, keep stirring at 30 °C for 24 h for crystal cultivation to make the crystals continue to precipitate and the particles grow.

[0117] (4)Centrifugal drying: After the crystallization is completed, transfer the sugar paste to a centrifuge for centrifugation. During centrifugation, when no mother liquor is observed to secrete, intermittently spray high-purity water for washing until the crystals in the centrifuge turn white as observed through the sight glass and the washing liquid no longer secretes, then stop centrifugation. Transfer the centrifuged crystals to a fluidized bed for staged drying. The temperature of the hot air section is 95°C - 105°C, the temperature of the warm air section is 50°C - 60°C, and the temperature of the cold air section is 20°C - 25°C. Control the moisture content of the dried arabinose to be <0.5%. The yield of arabinose is 60.32%. Yield = mass of arabinose after drying / mass of arabinose in the crystallization raw material * 100%;

[0118] Example 2

[0119] The difference between Example 2 and Example 1 lies in the staged cooling rate in the crystallization step: in the first stage, cool from 65°C - 67°C to 55°C at a rate of 0.3°C / h; in the second stage, cool from 55°C to 45°C at a rate of 0.75°C / h; in the third stage, cool from 45°C to 30°C at a rate of 1.35°C / h.

[0120] Example 3

[0121] The difference between Example 3 and Example 1 lies in the staged cooling rate in the crystallization step: in the first stage, cool from 65°C - 67°C to 55°C at a rate of 0.3°C / h; in the second stage, cool from 55°C to 45°C at a rate of 0.75°C / h; in the third stage, cool from 45°C to 30°C at a rate of 1.5°C / h.

[0122] Example 4

[0123] The difference between Example 4 and Example 1 lies in the staged cooling rate in the crystallization step: in the first stage, cool from 65°C - 67°C to 55°C at a rate of 0.3°C / h; in the second stage, cool from 55°C to 45°C at a rate of 0.85°C / h; in the third stage, cool from 45°C to 30°C at a rate of 1.5°C / h.

[0124] Example 5

[0125] The difference between Example 5 and Example 1 lies in the staged cooling rate in the crystallization step: in the first stage, cool from 65°C - 67°C to 55°C at a rate of 0.3°C / h; in the second stage, cool from 55°C to 45°C at a rate of 1°C / h; in the third stage, cool from 45°C to 30°C at a rate of 1.5°C / h.

[0126] Example 6

[0127] Example 6 is different from Example 1 in that the stepwise cooling rate in the crystallization step is as follows: in the first stage, it is cooled from 65°C to 67°C to 55°C at a cooling rate of 0.4°C / h; in the second stage, it is cooled from 55°C to 45°C at a cooling rate of 1°C / h; in the third stage, it is cooled from 45°C to 30°C at a cooling rate of 1.5°C / h.

[0128] Example 7

[0129] Example 7 is different from Example 1 in that the stepwise cooling rate in the crystallization step is as follows: in the first stage, it is cooled from 65°C to 67°C to 55°C at a cooling rate of 0.5°C / h; in the second stage, it is cooled from 55°C to 45°C at a cooling rate of 1°C / h; in the third stage, it is cooled from 45°C to 30°C at a cooling rate of 1.5°C / h.

[0130] Example 8

[0131] Example 8 is different from Example 7 in that the seeding time in the crystallization step is 12 hours.

[0132] Example 9

[0133] Example 9 is different from Example 7 in that the seeding time in the crystallization step is 48 hours.

[0134] Comparative Example 1

[0135] Comparative Example 1 is different from Example 7 in that there is no seeding time in the crystallization step (the seeding time is 0 hours).

[0136] Comparative Example 2

[0137] Comparative Example 2 is different from Example 1 in that there is no seeding time in the crystallization step (the seeding time is 0 hours).

[0138] Comparative Example 3

[0139] Comparative Example 3 is different from Example 1 in that the stepwise cooling in the crystallization step is changed to continuous cooling at a fixed cooling rate of 1°C / h to 30°C, and seeding is carried out for 24 hours.

[0140] Comparative Example 4

[0141] Comparative Example 4 is different from Example 1 in that: the crystallization is carried out using finished arabinose with a sugar content of 99.1% as the raw material. The stepwise cooling in the crystallization step is changed to continuous cooling at a fixed cooling rate of 1°C / h to 50°C, without seeding, and directly centrifuged.

[0142] Comparative Example 5

[0143] (1) Xylose mother liquor treatment: The xylose mother liquor is fermented to obtain a pretreatment solution.

[0144] (2) Preparation of crystallization raw materials: After subjecting the pretreatment liquid obtained in the previous step to chromatographic separation, activated carbon accounting for 0.1% of the mass of the sugar solution was added to the chromatographic fraction with an arabinose content of 75.43% at 60 °C. After stirring for 40 min, the activated carbon was removed by filtration to obtain a decolorized sugar solution. After removing salts and some residual pigments from the decolorized sugar solution through an ion exchange system, it was concentrated to a sugar concentration of 60% and used as the crystallization raw material.

[0145] (3) Fed-batch crystallization: Half of the crystallization raw material obtained in the previous step was added to a vacuum reactor for negative pressure concentration. The concentration temperature was controlled at 65 °C - 67 °C. When the sugar concentration reached 72%, arabinose with a mesh size of 80 - 100 and accounting for 0.03% of the mass of the bottom material was added as crystal seeds. After stirring evenly, the remaining sugar solution was added dropwise, and the addition was controlled to be completed in about 11 hours.

[0146] (4) Centrifugal drying: After the addition was completed, the concentration was continued for 1 hour, and then it was transferred to a centrifuge for centrifugation. During centrifugation, when no mother liquor was observed to secrete, high-purity water was intermittently sprayed for washing until the crystals in the centrifuge turned white as observed through the sight glass and the washing liquid no longer secreted, then the centrifugation was stopped. The centrifuged crystals were transferred to a fluidized bed for staged drying. The temperature of the hot air section was 95 °C - 105 °C, the temperature of the warm air section was 50 °C - 60 °C, and the temperature of the cold air section was 20 °C - 25 °C. The water content of the dried arabinose was controlled to be <0.5%. The yield of arabinose was 47.93%.

[0147] Comparative Example 6

[0148] (1) Fed-batch crystallization: The finished arabinose with a content of 99.1% was dissolved at 60 °C to a sugar concentration of 50%. Half of it was added to a vacuum reactor for negative pressure concentration until the sugar concentration reached 59%. Arabinose with a mesh size of 80 - 100 and accounting for 0.03% of the mass of the bottom material was added as crystal seeds. After stirring evenly, the remaining sugar solution was added dropwise, and the addition was controlled to be completed in about 11 hours.

[0149] (2) Centrifugal drying: After the addition was completed, the concentration was continued for 1 hour, and then it was transferred to a centrifuge for centrifugation. During centrifugation, when no mother liquor was observed to secrete, high-purity water was intermittently sprayed for washing until the crystals in the centrifuge turned white as observed through the sight glass and the washing liquid no longer secreted, then the centrifugation was stopped. The centrifuged crystals were transferred to a fluidized bed for staged drying. The temperature of the hot air section was 95 °C - 105 °C, the temperature of the warm air section was 50 °C - 60 °C, and the temperature of the cold air section was 20 °C - 25 °C. The water content of the dried arabinose was controlled to be <0.5%. The yield of arabinose was 45.43%.

[0150] Comparative Example 7

[0151] The difference between Comparative Example 7 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooled from 65°C~67°C to 55°C, the cooling rate is 0.5°C / h, the second stage is cooled from 55°C to 45°C, the cooling rate is 1°C / h, the third stage is cooled from 45°C to 30°C, the cooling rate is 0.5°C / h, and the arabinose yield is 52.32%.

[0152] Comparative Example 8

[0153] The difference between Comparative Example 8 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooled from 65°C~67°C to 55°C, the cooling rate is 1.5°C / h, the second stage is cooled from 55°C to 45°C, the cooling rate is 1°C / h, the third stage is cooled from 45°C to 30°C, the cooling rate is 0.5°C / h, and the arabinose yield is 50.87%.

[0154] The performance of the arabinose obtained in each example and comparative example was tested according to the following method:

[0155] The dried arabinose was tested for bulk density, tap density, compression, Hausner ratio, and angle of repose, and the average value was obtained after three tests. The packaging application was tested on a three-sided peak powder packaging machine, especially to observe whether the packaging material was unloaded smoothly and whether the bag was stuck during the packaging process.

[0156] The main instruments and detection methods used in the above experiments and detection processes are as follows:

[0157] Electron microscope: TESCAN CLARA field emission scanning electron microscope;

[0158] Sugar concentration: tested with a handheld saccharimeter;

[0159] Arabinose content: HPLC detection, area normalization method calculation;

[0160] Solid content: The percentage of crystals obtained by centrifugation of the massecuite in the sugar boiling tank;

[0161] Angle of repose: The angle of repose tester complies with the national standard GB11986-89 and the international standard ISO4324-1977; three repetitive tests are performed for each test and the average value is taken. When the angle of repose is greater than 60°, no reading can be made, and at the same time, the compression is greater than 38%, and the Hausner ratio is greater than 1.60, the fluidity is judged to be very poor.

[0162] Bulk density: Detected by FT-103 natural loose bulk density meter, in line with standard GB / T 16913.3-1997.

[0163] Tap density: tested by HY-100A powder density tester.

[0164] Application detection: The finished arabinose was detected for its packaging situation on an automatic packaging machine for powder and granule preparations, and the fluidity of its feeding was observed. The equipment used was the DXD-F type three-side sealed powder bagging machine from Jinan Tianlu, taking 15 g per bag as an example.

[0165] The main parameters, test results, etc. of each example and comparative example are shown in Table 1 and Table 2.

[0166] Table 1

[0167]

[0168] Table 2

[0169]

[0170] It can be seen from the experimental results of the above examples and comparative examples that:

[0171] (1) By adopting the staged cooling crystallization method proposed in this application and continuing to carry out crystal cultivation after cooling, a relatively high product yield can be obtained, all of which can reach more than 50%. Moreover, the product has excellent fluidity, and the feeding is smooth during small-bag packaging without bag clamping. Especially when the cooling rate is relatively slow in the first and second stages of staged cooling (such as in Examples 1-5), the product yield is higher (up to more than 60% at most), and the fluidity is also better (repose angle < 30°, bulk density > 0.8 g / cm 3 )

[0172] (2) The results of Examples 1 and 9 and Comparative Examples 1 and 2 show that after the staged cooling is completed and centrifugation is carried out immediately without the crystal cultivation step, the repose angle of the product becomes larger than 45°, the fluidity is poor, and there will be jams during feeding when applied to small-bag packaging, resulting in occasional bag clamping of the material.

[0173] (3) The result of Comparative Example 3 shows that when the staged cooling crystallization method is not adopted and the whole cooling process is carried out at a constant rate and crystal cultivation is carried out, when the raw material arabinose content is relatively low, the yield can be > 50%, but the repose angle cannot be read, and the changed repose angle > 60°, and there is jamming during feeding when applied to small-bag packaging, resulting in bag clamping of the material, indicating that its fluidity is very poor.

[0174] (4) The result of Comparative Example 4 shows that when using the finished arabinose (purity > 99%) as the raw material for crystallization and the whole cooling process is carried out at a constant rate, when the temperature drops to 50 °C, due to high supersaturation, the sugar paste is viscous, the stirring current suddenly increases, and the load is too high, and centrifugation must be carried out. As a result, the product yield obtained is low and the fluidity is poor.

[0175] (5) Comparative Examples 5 and 6 adopt conventional fed-batch crystallization, and the product yield is low and the fluidity is relatively poor.

[0176] (6)Comparative Examples 7 and 8 show that the cooling rate during the staged cooling process is also important. If the cooling rate does not increase gradually stage by stage (such as when using a cooling rate that is fast first and then slow or slow at the beginning and end and fast in the middle), although the yield can reach 50% after 24 hours of crystal cultivation, the bulk density of the product is extremely low, the angle of repose > 60°, and the fluidity is extremely poor.

[0177] In summary, using a staged cooling with a cooling rate that is slow first and then fast can significantly improve the fluidity of the arabinose product, making its angle of repose < 40°, and when the cooling rate is extremely slow in the high-temperature stage, the angle of repose < 30°, and the bulk density > 0.8 g / cm 3 ; Further improving the fluidity and significantly increasing the yield to 60% through crystal cultivation. In actual production, an extremely slow cooling rate can be used within the range of the cooling rate according to application requirements to obtain higher fluidity; or, on the premise of meeting the application requirements, the cooling rate can be appropriately increased within the range to shorten the production time and improve production capacity.

[0178] The above are only the preferred embodiments of the present application, and are not intended to limit the present application in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present application without departing from the technical solution content of the present application still belong to the protection scope of the technical solution of the present application.

Claims

1. A method for preparing highly fluid L - arabinose crystals, which comprises the following steps: Treatment of xylose mother liquor: Fermenting the xylose mother liquor to obtain a pretreated solution; Preparation of crystallization raw material: Separating an arabinose - fractionated liquor from the pretreated solution as the crystallization raw material; Crystallization: Adding seed crystals to the crystallization raw material and performing staged cooling crystallization at different cooling rates, and carrying out crystal ripening for a certain period of time after the cooling is completed to obtain the L - arabinose crystals, wherein, the seed crystals are arabinose with a mesh size of 80 to 100; the staged cooling sequentially includes a first cooling stage, a second cooling stage, and a third cooling stage. In the first cooling stage, the crystallization temperature is reduced to 55 °C, in the second cooling stage, the crystallization temperature is reduced to 45 °C, and in the third cooling stage, the crystallization temperature is reduced to 28 - 35 °C. The cooling rate in the first cooling stage is 0.3 °C / h to 0.5 °C / h, the cooling rate in the second cooling stage is 0.5 °C / h to 1.0 °C / h, and the cooling rate in the third cooling stage is 1.0 °C / h to 1.5 °C / h, and the cooling rates in the first cooling stage, the second cooling stage, and the third cooling stage increase sequentially; the temperature for crystal ripening is 28 - 35 °C, and the crystal ripening time is 12 - 48 h.

2. The preparation method according to claim 1, wherein The solid content of the L - arabinose crystals obtained after crystal ripening is ≥50%.

3. The preparation method according to claim 1, wherein, In the step of treating the xylose mother liquor, it includes removing miscellaneous sugars in the xylose mother liquor by fermentation.

4. The preparation method according to claim 1, wherein The step of treating the xylose mother liquor further includes filtering to remove impurities in the xylose mother liquor after fermentation.

5. The preparation method according to claim 1, wherein, The step of treating the xylose mother liquor further includes concentrating the xylose mother liquor after fermentation.

6. According to the preparation method described in claim 1, wherein, In the step of preparing the crystallization raw material, the arabinose - fractionated liquor is obtained by chromatographic separation.

7. The preparation method according to claim 1, wherein, The step of preparing the crystallization raw material further includes performing decolorization treatment on the arabinose - fractionated liquor.

8. The preparation method according to claim 1, wherein, The step of preparing the crystallization raw material further includes performing desalting treatment on the arabinose - fractionated liquor.

9. The preparation method according to claim 1, wherein, The step of preparing the crystallization raw material further includes performing concentration treatment on the arabinose - fractionated liquor.

10. The preparation method according to claim 1, wherein, In the crystallization step, it further includes performing negative - pressure concentration on the crystallization raw material before crystallization.

11. According to the preparation method described in claim 1, wherein, The preparation method further includes a step of centrifugal separation after crystal ripening.

12. The preparation method according to claim 1, wherein, The preparation method further includes a step of drying after crystal ripening.

13. Use of the L - arabinose crystals prepared by the preparation method according to any one of claims 1 to 12 in the preparation of powder products.

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