Process for the synthesis and purification of allulose

Abstract

The invention relates to a process for the preparation of an allulose product comprising enzymatic conversion of fructose into allulose; chromatographically separating the thus obtained crude product into (i) one or more allulose enriched fractions, (ii) a fructose enriched fraction, and optionally (iii) a purge fraction, preferably by simulated moving bed chromatography; and recirculating the fructose enriched fraction to the enzymatic conversion.

Description

Process for the synthesis and purification of allulose

[0001] Priority is claimed of European patent application no. 24 152 156.6 that was filed on January 16, 2024.

[0002] The invention relates to a process for the preparation of an allulose product comprising enzymatic conversion of fructose into allulose; chromatographically separating the thus obtained crude product into (i) one or more allulose enriched fractions, (ii) a fructose enriched fraction, and optionally (iii) a purge fraction, preferably by simulated moving bed chromatography; and recirculating the fructose enriched fraction to the enzymatic conversion.

[0003] The enzymatically catalyzed conversion of fructose into allulose is known from the prior art. Due to product inhibition and other factors affecting the enzymatically catalyzed conversion, the conversion is not complete. On the contrary, considerable amounts of residual fructose remain as not converted starting material in the crude product. As it is desirable to provide allulose products with high degree of purity, residual fructose needs to be separated from the allulose. This can be achieved by chromatography, typically by simulated moving bed (SMB) chromatography, providing an allulose enriched fraction and a fructose enriched fraction. As the fructose enriched fraction typically contains a significant amount of fructose, the fructose enriched fraction is advantageously recirculated into the process.

[0004] Depending upon the source of fructose that is used for providing the starting material, the starting material may contain other carbohydrates.

[0005] When the fructose is obtained from sucrose, sucrose may be cleaved into a 1: 1 mixture of fructose and glucose (invert sugar), and the glucose may be separated from the fructose, e.g. by chromatography. Preferably, the glucose may first be isomerized into fructose under enzymatic catalysis of a suitable isomerase and subsequently, merely the residual, i.e. not isomerized glucose may be separated from the fructose, e.g. by chromatography. In either case, the thus purified fructose may still contain certain amounts of glucose and / or sucrose.

[0006] When the fructose is obtained from starch or cellulose, the starch or cellulose may first be degraded into glucose and subsequently be isomerized into fructose under enzymatic catalysis of a suitable isomerase. Subsequently, the residual, i.e. not isomerized glucose may likewise be separated from the fructose, e.g. by chromatography. Under these circumstances, the thus purified fructose may still contain certain amounts of glucose and / or glucooligosaccharides and / or cellooligosaccharides.

[0007] Furthermore, depending upon the subsequent work-up measures and recirculation streams, additional byproducts and impurities may be formed, e.g. at elevated temperatures. The content of suchbyproducts and impurities in the allulose product should be as low as possible. Therefore, the chromatographic separation of allulose and fructose is typically optimized with respect to the purity of the allulose enriched fraction thereby compromising the purity of the fructose enriched fraction, which besides fructose should contain the majority of byproducts and impurities.

[0008] When after chromatographic separation of allulose and fructose the fructose enriched fraction is recirculated into the process, however, the byproducts and impurities are likewise recirculated and are enriched over time. Every recirculation step increases the overall content of byproducts and impurities in the circulation. In order to discharge the byproducts and impurities from the circulation, it is necessary from time to time to purge the byproducts and impurities along with the fructose enriched fraction thereby purging valuable fructose as well. This is disadvantageous from an economic perspective.

[0009] There is a demand for processes for the production of allulose from fructose that overcome these drawbacks of the prior art.

[0010] Simulated moving bed (SMB) chromatography is known to the skilled person and has been used in the preparation of allulose and allulose containing products (see e.g. N. Wagner et al., Org. Process Res. Dev. 2012, 16, 323-330; N. Wagner et al., Journal of Chromatography A, 1398 (2015) 47-56; N. Wagner et al., Angew. Chem. Int. Ed. 2015, 54, 4182-4186; N. Wagner et al., Chemical Engineering Science 137 (2015) 423-435; X. Wen et al., Process Biochemistry, vol. 119, 2022, pp. 29-38; US 4,692,514, US 4,880,920, US 2010 0213130, US 2017 0313734, US 2019 0177351, US 2019 0315790 (WO 2018 / 087261 Al), US 2019 0315791, US 20200157131, US 2020 0172945, US 2020 0377540, US 2020 0385415, US 2020 0407389, US 2021 0324434, US 2022 0315618, US 2022 0380400, US 2023 0046104, and US 2023 0058087).

[0011] WO 2021 146134 Al relates to a method comprising separating a mixture of allulose, fructose, glucose, and glucooligosaccharides, wherein the separating comprises using simulated moving bed chromatography, and recovering allulose at a high purity and yield.

[0012] WO 2022 239027 Al relates to a system and method for purifying D-allulose and / or fructose from a binary mixture.

[0013] EP 3 553 069 Al relates to a method for utilizing fructose raffinate obtained in the process for separating psicose conversion product with a high purity chromatography in the process for preparing psicose.

[0014] FR 3 061 413 Al relates to a process for the manufacture of D-allulose crystals which makes it possible to work continuously and to obtain a high yield. It further relates to the use of a nanofiltration unit in a process for producing D-allulose crystals in order to improve the yield and / or the quality of the crystals obtained.

[0015] US 11 401 292 B2 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.

[0016] It is an object of the invention to provide a process for the preparation of allulose from fructose that has advantages over the prior art. The process should allow for economic preparation of allulose products with high purity on industrial scale. Disposal of valuable substances such as residual fructose should be minimized.

[0017] This object has been achieved by the subject-matter of the patent claims.

[0018] A first aspect of the invention relates to a process for the preparation of an allulose product comprising the steps of(a) providing a starting composition comprising(a) fructose and(P) optionally, one or more impurities and / or glucose and / or sucrose;(b) contacting the starting composition with an allulose-3 -epimerase to convert fructose into allulose thereby obtaining a crude product comprising(a) allulose,(P) fructose, and(y) one or more impurities and / or glucose and / or sucrose;(c) optionally, subjecting the crude product to one or more pre-purification measures thereby obtaining a pre-purified product comprising(a) allulose,(P) fructose, and(y) one or more impurities and / or glucose and / or sucrose;(d) chromatographically separating the crude product or the pre-purified product into(a) one or more allulose enriched fractions (extract) each having independently of one another an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction;(P) a fructose enriched fraction (raffinate) having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; and(y) optionally, a purge fraction enriched with one or more impurities and / or glucose and / or sucrose;(e) optionally, subjecting the fructose enriched fraction to one or more concentration and / or purification measures thereby obtaining a concentrated and / or purified fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the concentrated and / or purified fructose enriched fraction;(f) recirculating the fructose enriched fraction or the concentrated and / or purified fructose enriched fraction to step (a) or (b); wherein the one or more impurities are any organic compounds other than allulose, fructose, glucose, and sucrose.

[0019] The process according to the invention comprises steps (a), (b), (d) and (f), and optionally also(c) and / or (e). In preferred embodiments, the process comprises steps (a), (b), (c), (d) and (f); or (a), (b),(d), (e) and (f); or (a), (b), (c), (d), (e) and (f).

[0020] Preferably, the process steps are performed in alphabetical order.

[0021] In preferred embodiments, the process is performed as a batch process.

[0022] In other preferred embodiments, the process is performed as a semi-batch process.

[0023] In further preferred embodiments, the process is performed continuously. The skilled person recognizes that under these circumstances, one or more of the process steps may be performed simultaneously or at least partially simultaneously.

[0024] Unless expressly stated otherwise, all percentages are weight percent. Unless expressly stated otherwise, all percentages are relative to the dry solid content of the respective process flow.

[0025] For the purpose of the specification, "and / or" means "either", "or" or "as well as", i.e. "A and / or B" means "either A hut not B", or "B but not A", or "A as well as B" .

[0026] Unless expressly stated otherwise, all carbohydrates are present in D-configuration. While it is contemplated that the U-configuration is also present, the D-configuration is preferred.

[0027] Unless expressly stated otherwise, impurities are any organic compounds other than allulose, fructose, glucose, and sucrose.

[0028] In preferred embodiments, in step (d) the crude product or the pre-purified product is chroma- tographically separated into(a) one or more allulose enriched fractions (extract) each having independently of one another an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction;(P) a fructose enriched fraction (raffinate) having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; and(y) a purge fraction enriched with one or more impurities and / or glucose and / or sucrose, i.e. the purge fraction is mandatory.

[0029] In preferred embodiments, the allulose product is solid, preferably at least partially crystalline.

[0030] In other preferred embodiments, the allulose product is liquid, preferably a syrup.

[0031] In step (a) of the process according to the invention, a starting composition is provided comprising (a) fructose and ( ) optionally, one or more impurities and / or glucose and / or sucrose.

[0032] Preferably, the starting composition has a fructose content of at least 40 wt.-%, preferably at least 60 wt.-%, more preferably at least 70 wt.-%, yet more preferably at least 80 wt.-%, even more preferably at least 90 wt.-%, most preferably at least 95 wt.-%, and in particular at least 98 wt.-%, relative to the dry solids content of the starting composition.

[0033] Preferably, the starting composition comprises glucose.

[0034] Preferably, the starting composition has a glucose content of at most 8.0 wt.-%, preferably at most 7.0 wt.-%, more preferably at most 6.0 wt.-%, yet more preferably at most 5.0 wt.-%, even more preferably at most 4.0 wt.-%, most preferably at most 3.0 wt.-%, and in particular at most 2.0 wt.-%, relative to the dry solids content of the starting composition.

[0035] Preferably, the starting composition has a glucose content of at least 0.0001 wt.-%, preferably at least 0.001 wt.-%, more preferably at least 0.01 wt.-%, yet more preferably at least 0.1 wt.-%, even more preferably at least 0.2 wt.-%, most preferably at least 0.3 wt.-%, and in particular at least 0.4 wt.- %, relative to the dry solids content of the starting composition.

[0036] Preferably, the starting composition comprises sucrose.

[0037] Preferably, the starting composition has a sucrose content of at most 1.8 wt.-%, preferably at most 1.6 wt.-%, more preferably at most 1.4 wt.-%, yet more preferably at most 1.2 wt.-%, even more preferably at most 1.0 wt.-%, most preferably at most 0.8 wt.-%, and in particular at most 0.6 wt.-%, relative to the dry solids content of the starting composition.

[0038] In step (b) pf the process according to the invention, the starting composition provided in step (a) is contacted with an allulose-3 -epimerase to convert fructose into allulose thereby obtaining a crude product comprising (a) allulose, ( ) fructose, and (y) one or more impurities and / or glucose and / or sucrose.

[0039] Suitable allulose-3 -epimerases and reaction conditions are known to the skilled person. Certain tagatose 3-epimerases can also be used (see e.g. S. Jiang et al., Review on D-Allulose: In vivo Metabolism, Catalytic Mechanism, Engineering Strain Construction, Bio-Production Technology, Front Bioeng Biotechnol. 2020 Feb 3:8:26, 1-10).

[0040] In preferred embodiments, at least one of the one or more impurities is formed in step (b), e.g. as a byproduct of the enzymatically catalyzed conversion.

[0041] In preferred embodiments, at least one of the one or more impurities is formed in one or more steps subsequent to step (b), e.g. during work-up at elevated temperature.

[0042] Preferably, the one or more impurities comprise allulose dimer, allulose-fructose disaccharide, allulose-glucose disaccharide, allulose tetramer, diallulose anhydride, levulinic acid, y-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-furanedialdehyde, 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-dimethoxyfurane, (2R)-5-oxotetrahydro- 2-furane carboxylic acid, bis(5-methyl furfuryl)ether, 5,5'-methylene-di(furane-2-carboxylic acid), or any combination thereof.

[0043] Preferably, the one or more impurities comprise lactic acid, maltol, furaneol, allosone, glucosone, 1 -desoxyglucosone, 3 -desoxyglucosone, 3-desoxygalactosone, formic acid, acetic acid, propionic acid, glyoxal, or any combination thereof.

[0044] Preferably, the one or more impurities comprise 2,3-butanedione, acetaldehyde, 2-keto-D-glu- cose (glucosone), 3 -desoxyglucosone, or any combination thereof.

[0045] In particularly preferred embodiments, the one or more impurities comprise 2,3-butanedione (diacetyl), i.e. CH3C(=O)C(C=O)CH3.

[0046] In particularly preferred embodiments, the one or more impurities comprise acetaldehyde, i.e. CH3C(=O)H.

[0047] In particularly preferred embodiments, the one or more impurities comprise 2-keto-D-glucose (glucosone), i.e.

[0048] In particularly preferred embodiments, the one or more impurities comprise allosone, i.e.

[0049] In particularly preferred embodiments, the one or more impurities comprise 3 -desoxyglucosone, i.e.

[0050] Preferably, the crude product has a total content of impurities of at least 0.0001 wt. -%, preferably at least 0.001 wt.-%, more preferably at least 0.01 wt.-%, yet more preferably at least 0.1 wt.-%, even more preferably at least 0.2 wt.-%, most preferably at least 0.3 wt.-%, and in particular at least 0.5 wt.- %, relative to the dry solids content of the crude product.

[0051] Preferably, the crude product has a total content of impurities of at most 7.0 wt.-%, preferably at most 6.0 wt.-%, more preferably at most 5.0 wt.-%, yet more preferably at most 4.0 wt.-%, even more preferably at most 3.0 wt.-%, most preferably at most 2.0 wt.-%, and in particular at most 1.0 wt.-%, relative to the dry solids content of the crude product.

[0052] Preferably, the crude product has an allulose content of at least 15 wt.-%, preferably at least 23 wt.-%, more preferably at least 32 wt.-%, yet more preferably at least 40 wt.-%, even more preferably at least 48 wt.-%, most preferably at least 57 wt.-%, and in particular at least 65 wt.-%, relative to the dry solids content of the crude product.

[0053] Preferably, the crude product has a fructose content of at most 85 wt.-%, preferably at most 77 wt.-%, more preferably at most 68 wt.-%, yet more preferably at most 60 wt.-%, even more preferably at most 52 wt.-%, most preferably at most 44 wt.-%, and in particular at most 35 wt.-%, relative to the dry solids content of the crude product.

[0054] Preferably, the crude product has a glucose content of at most 8.0 wt.-%, preferably at most 7.0 wt.-%, more preferably at most 6.0 wt.-%, yet more preferably at most 5.0 wt.-%, even more preferably at most 4.0 wt.-%, most preferably at most 3.0 wt.-%, and in particular at most 2.0 wt.-%, relative to the dry solids content of the crude product.

[0055] Preferably, the crude product has a sucrose content of at most 5.00 wt.-%, preferably at most 4.25 wt.-%, more preferably at most 3.50 wt.-%, yet more preferably at most 2.75 wt.-%, even more preferably at most 2.00 wt.-%, most preferably at most 1.25 wt.-%, and in particular at most 0.50 wt.- %, relative to the dry solids content of the crude product.

[0056] Preferably, the crude product 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 crude product.

[0057] Preferably, the crude product 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 crude product.

[0058] Preferably, the crude product 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 crude product.

[0059] Preferably, the crude product 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 4,000ppmw, 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 crude product.

[0060] Preferably, the crude product 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 crude product.

[0061] Preferably, the crude product 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 crude product.

[0062] In optional step (c) of the process according to the invention, the crude product obtained in step (b) is subjected to one or more pre-purification measures thereby obtaining a pre-purified product comprising (a) allulose, ( ) fructose, and (y) one or more impurities and / or glucose and / or sucrose.

[0063] Preferably, the one or more pre-purification measures comprise a filtration, preferably an ultrafiltration.

[0064] Suitable methods for filtration including ultrafiltration are known to the skilled person and suitable membranes are commercially available. Typical membranes and pore filters have separation limits between 0.1 and 0.01 pm.

[0065] Preferably, the one or more pre-purification measures comprise a demineralization and / or a decoloration (discoloration).

[0066] Suitable methods for demineralization are known to the skilled person and include but are not limited to ion exchange chromatography. Suitable ion exchange resins are commercially available.

[0067] Suitable methods for decoloration are likewise known to the skilled person and include but are not limited to adsorption. Suitable adsorbents such as active charcoal are commercially available.

[0068] In step (d) of the process according to the invention, the crude product obtained in step (b) or the pre-purified product obtained in optional step (c) is chromatographically separated into(a) one or more allulose enriched fractions each having independently of one another an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction;(P) a fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; and(y) optionally, a purge fraction enriched with one or more impurities and / or glucose and / or sucrose.

[0069] In preferred embodiments, the crude product obtained in step (b) or the pre-purified product obtained in optional step (c) that is subjected to chromatographic separation(a) has a dry solids content (dry substance content) within the range of 55.0± 15.0 wt.-%, preferably 55.0± 13.0 wt.-%, more preferably 55.0± 11.0 wt.-%, still more preferably 55.0±9.0 wt.-%, yet more preferably 55.0±7.0 wt.-%, even more preferably 55.0±6.0 wt.-%, most preferably 55.0±5.0 wt.-%, and in particular 55.0±4.0 wt.-%, relative to the total weight of the crude product and the prepurified product, respectively; and / or(P) has an allulose content within the range of 30.0±12.0 wt.-%, preferably 30.0±11.0 wt.-%, more preferably 30.0±10.0 wt.-%, still more preferably 30.0±9.0 wt.-%, yet more preferably 30.0±8.0 wt.-%, even more preferably 30.0±7.0 wt.-%, most preferably 30.0±6.0 wt.-%, and in particular 30.0±5.0 wt.-%, relative to the dry solids content of the crude product and the pre-purified product, respectively; and / or(y) has a fructose content within the range of 65.0±12.0 wt.-%, preferably 65.0±11.0 wt.-%, more preferably 65.0±10.0 wt.-%, still more preferably 65.0±9.0 wt.-%, yet more preferably 65.0±8.0 wt.- %, even more preferably 65.0±7.0 wt.-%, most preferably 65.0±6.0 wt.-%, and in particular 65.0±5.0 wt.-%, relative to the dry solids content of the crude product and the pre-purified product, respectively; and / or(5) has a glucose content within the range of 1.7±1.7 wt.-%, preferably 1.7±1.5 wt.-%, more preferably 1.7±1.3 wt.-%, still more preferably 1.7±1.1 wt.-%, yet more preferably 1.7±0.9 wt.-%, even more preferably 1.7±0.7 wt.-%, most preferably 1.7±0.5 wt.-%, and in particular 1.7±0.3 wt.-%, relative to the dry solids content of the crude product and the pre-purified product, respectively; and / or(a) has a sucrose content within the range of 0.50±0.50 wt.-%, preferably 0.50±0.45 wt.-%, more preferably 0.50±0.40 wt.-%, still more preferably 0.50±0.35 wt.-%, yet more preferably 0.50±0.30 wt.- %, even more preferably 0.50±0.25 wt.-%, most preferably 0.50±0.20 wt.-%, and in particular 0.50±0. 15 wt. -%, relative to the dry solids content of the crude product and the pre-purified product, respectively.

[0070] Preferably, chromatographic separation provides- one or more allulose enriched fractions (extract), wherein relative to the dry solids content of the one or more allulose enriched fractions, the content of allulose is within the range of from 90 to 100 wt.- %, the content of fructose is within the range of from 0 to 5 wt.-% (50000 ppmw), and the content of glucose is within the range of from 0 to 0.5 wt.-% (5000 ppmw);- a fructose enriched fraction (raffinate), wherein relative to the dry solids content of the fructose enriched fraction, the content of fructose is within the range of from 90 to 100 wt.-%, the content of allulose is within the range of from 0 to 5 wt.-% (50000 ppmw), and the content of glucose is within the range of from 0 to 1.5 wt.-% (15000 ppmw).

[0071] Preferably, chromatographic separation comprises at least one simulated moving bed chromatography (SMB), more preferably sequential simulated moving bed chromatography (SSMB). Simulated moving bed chromatography is common general knowledge (see e.g. A.E. Rodrigues et al.,Simulated Moving Bed Technology - Principles, Design and Process Applications, Elsevier, 2015). Sequential Simulated Moving Bed (SSMB) technology is a modified SMB technique featured by dividing a switching period into 3 sub-steps resulting in different flow patterns to reduce solvent consumption at high purity.

[0072] Suitable stationary phases for SMB are known to the skilled person. Preferred stationary phases are strong acid ion exchange resins in the calcium form. Suitable resins are commercially available, e.g. from Purolite® Corporation or Dow Chemicals, e.g. DOWEX® 50 WX4-400.

[0073] As illustrated in Figure 3, the SMB is characterized by the ratio of the volume of fresh water to the volume of feed, i.e. the water to feed ratio. According to the invention, a low value for the water to feed ratio (v / v) of the SMB is desirable.

[0074] Preferably, the water to feed ratio (v / v) of the SMB is at most 4.0, more preferably at most 3.7, still more preferably at most 3.4, yet more preferably at most 3.1, even more preferably at most 2.8, most preferably at most 2.5, and in particular at most 2.2.

[0075] Preferably, the water to feed ratio (v / v) of the SMB is at least 0.8, more preferably at least 0.9, still more preferably at least 1.0, yet more preferably at least 1.1, even more preferably at least 1.2, most preferably at least 1.3, and in particular at least 1.4.

[0076] A water to feed ratio (v / v) of the SMB within the range of from 1.5 to 3.6 is particularly preferred. In preferred embodiments, the water to feed ratio (v / v) of the SMB is within the range of from 1.5 to 2.0. In preferred embodiments, the water to feed ratio (v / v) of the SMB is within the range of from 2.0 to 3.6.

[0077] Further, as also illustrated in Figure 3, the SMB is characterized by the ratio of the volume of the extract (product) to the volume of the raffinate, i.e. the extract to raffinate ratio. The extract to raffinate ratio corresponds to the ratio of the volume of the allulose enriched fraction to the volume of the fructose enriched fraction.

[0078] Preferably, the extract to raffinate ratio (v / v) of the SMB is at most 1.6, more preferably at most 1.5, still more preferably at most 1.4, yet more preferably at most 1.3, even more preferably at most 1.2, most preferably at most 1.1, and in particular at most 1.0.

[0079] Preferably, the extract to raffinate ratio (v / v) of the SMB is 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.

[0080] In preferred embodiments, the extract to raffinate ratio (v / v) of the SMB is within the range of 0.64±0.40, preferably 0.64±0.35, more preferably 0.64±0.30, still more preferably 0.64±0.25, yet more preferably 0.64±0.20, even more preferably 0.64±0.15, most preferably 0.64±0.10, and in particular preferably 0.64±0.05.

[0081] In further preferred embodiments, the extract to raffinate ratio (v / v) of the SMB is within the range of 0.88±0.40, preferably 0.88±0.35, more preferably 0.88±0.30, still more preferably 0.88±0.25, yet more preferably 0.88±0.20, even more preferably 0.88±0. 15, most preferably 0.88±0.10, and in particular preferably 0.88±0.05.

[0082] In other preferred embodiments, the extract to raffinate ratio (v / v) of the SMB is within the range of 0.99±0.40, preferably 0.99±0.35, more preferably 0.99±0.30, still more preferably 0.99±0.25, yet more preferably 0.99±0.20, even more preferably 0.99±0.15, most preferably 0.99±0.10, and in particular preferably 0.99±0.05.

[0083] Preferably, the purity of allulose in the extract, i.e. in the allulose enriched fraction, is at least 93%, more preferably at least 94%, still more preferably at least 95%, yet more preferably at least 96%, even more preferably at least 97%, most preferably at least 98%, and in particular at least 99%.

[0084] A purity of allulose within the range of from 95 to 99 wt.-% is particularly preferred.

[0085] Preferably, the purity of allulose is determined by HPLC according to ICUMSA GS3-50.

[0086] The SMB is further characterized by the recovery of allulose, i.e. the amount of allulose in the extract (product) relative to the amount of allulose in the feed.

[0087] Preferably, the recovery of allulose is at least 79%, more preferably at least 80%, still more preferably at least 81%, yet more preferably at least 82%, even more preferably at least 83%, most preferably at least 84%, and in particular at least 85%.

[0088] Preferably, the recovery of allulose is at least 86%, more preferably at least 87%, still more preferably at least 88%, yet more preferably at least 89%, even more preferably at least 90%, most preferably at least 91%, and in particular at least 92%.

[0089] Preferably, the recovery of allulose is at least 93%, more preferably at least 94%, still more preferably at least 95%, yet more preferably at least 96%, even more preferably at least 97%, most preferably at least 98%, and in particular at least 99%.

[0090] In preferred embodiments, the process according to the invention includes a single simulated moving bed (SMB) chromatography, preferably a single sequential simulated moving bed chromatography (SSMB).

[0091] Preferably, in step (d) the crude product obtained in step (b) or the pre-purified product obtained in optional step (c) is then chromatographically separated into(a) an allulose enriched fraction having an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction;(P) a fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; and(y) a purge fraction enriched with one or more impurities and / or glucose and / or sucrose.

[0092] In flow direction of the crude product obtained in step (b) or the pre-purified product obtained in optional step (c), the allulose enriched fraction is preferably separated downstream of the fructose enriched fraction.

[0093] In preferred embodiments, the purge fraction is chromatographically separated upstream of the fructose enriched fraction, and the allulose enriched fraction is separated downstream of the fructose enriched fraction (purge -> fructose -> allulose).

[0094] In other preferred embodiments, the fructose enriched fraction is chromatographically separated upstream of the allulose enriched fraction, and the purge fraction is separated downstream of the allulose enriched fraction (fructose -> allulose -> purge).

[0095] In further preferred embodiments, a first purge fraction is chromatographically separated upstream of the fructose enriched fraction, the allulose enriched fraction is separated downstream of the fructose enriched fraction, and a second purge fraction is separated downstream of the allulose enriched fraction (first purge -> fructose -> allulose -> second purge).

[0096] When a purge fraction is separated upstream of the fructose enriched fraction, the flow of the purge fraction preferably amounts to at most 9.0 wt.-% of the flow of the fructose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

[0097] When a purge fraction is separated downstream of the allulose enriched fraction, the flow of the purge fraction preferably amounts to at most 9.0 wt.-% of the flow of the allulose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

[0098] In other preferred embodiments, the process according to the invention includes two simulated moving bed (SMB) chromatographies, preferably two sequential simulated moving bed chromatographies (SSMB).

[0099] Preferably, step (d) comprises then the sub-steps(di) chromatographically separating the crude product or the pre-purified product into (a) a first allulose enriched fraction and (P) an intermediate fraction enriched with (i) fructose as well as (ii) one or more impurities and / or glucose and / or sucrose;(d2) chromatographically separating the intermediate fraction into (a) a second allulose enriched fraction; ( ) the fructose enriched fraction; and (y) the purge fraction; and(ds) optionally, combining the first allulose enriched fraction and the second allulose enriched fraction with one another.

[0100] In preferred embodiments, in flow direction of the crude product obtained in step (b) or the prepurified product obtained in optional step (c), in sub-step (di) the first allulose enriched fraction is preferably separated downstream of the intermediate fraction.

[0101] In preferred embodiments, the purge fraction is chromatographically separated upstream of the intermediate fraction, and the first allulose enriched fraction is separated downstream of the intermediate fraction (purge -> intermediate -> first allulose).

[0102] In other preferred embodiments, the intermediate fraction is chromatographically separated upstream of the first allulose enriched fraction, and the purge fraction is separated downstream of the first allulose enriched fraction (intermediate -> first allulose -> purge).

[0103] In further preferred embodiments, a first purge fraction is chromatographically separated upstream of the intermediate fraction, the first allulose enriched fraction is separated downstream of the intermediate fraction, and a second purge fraction is separated downstream of the first allulose enriched fraction (first purge -> intermediate -> first allulose -> second purge).

[0104] When a purge fraction is separated upstream of the intermediate fraction, the flow of the purge fraction preferably amounts to at most 9.0 wt.-% of the flow of the intermediate fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.- 0 / / o.

[0105] When a purge fraction is separated downstream of the first allulose enriched fraction, the flow of the purge fraction preferably amounts to at most 9.0 wt.-% of the flow of the first allulose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

[0106] In other preferred embodiments, in flow direction of the crude product obtained in step (b) or the pre-purified product obtained in optional step (c), in sub-step (d2) the second allulose enriched fraction is separated downstream of the fructose enriched fraction.

[0107] In preferred embodiments, the purge fraction is chromatographically separated upstream of the fructose enriched fraction, and the second allulose enriched fraction is separated downstream of the fructose enriched fraction (purge -> fructose -> second allulose).

[0108] In other preferred embodiments, the fructose enriched fraction is chromatographically separated upstream of the second allulose enriched fraction, and the purge fraction is separated downstream of the second allulose enriched fraction (fructose -> second allulose -> purge).

[0109] In further preferred embodiments, a first purge fraction is chromatographically separated upstream of the fructose enriched fraction, the second allulose enriched fraction is separated downstreamof the fructose enriched fraction, and a second purge fraction is separated downstream of the second allulose enriched fraction (first purge -> fructose -> second allulose -> second purge).

[0110] When a purge fraction is separated upstream of the fructose enriched fraction, the flow of the purge fraction preferably amounts to at most 9.0 wt.-% of the flow of the fructose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

[0111] When a purge fraction is separated downstream of the second allulose enriched fraction, the flow of the purge fraction preferably amounts to at most 9.0 wt.-% of the flow of the second allulose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

[0112] Irrespective of whether the process includes a single or two simulated moving bed chromatographies, the fractions that are chromatographically separated from one another have preferred compositions that are defined hereinafter:

[0113] Preferably, the one or more allulose enriched fractions independently of one another have an allulose content of at least 87.5 wt.-%, preferably at least 90.0 wt.-%, more preferably at least 92.5 wt.- %, yet more preferably at least 95.0 wt.-%, even more preferably at least 97.5 wt.-%, most preferably at least 98.5 wt.-%, and in particular at least 99.0 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

[0114] Preferably, the one or more allulose enriched fractions independently of one another have a fructose content of at most 12.5 wt.-%, preferably at most 7.5 wt.-%, more preferably at most 5.0 wt.- %, yet more preferably at most 2.5 wt.-%, even more preferably at most 1.0 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

[0115] Preferably, the one or more allulose enriched fractions independently of one another have a total content of impurities of at most 2.0 wt.-%, preferably at most 1.8 wt.-%, more preferably at most 1.6 wt.-%, still more preferably at most 1.4 wt.-%, and yet more preferably at most 1.2 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

[0116] Preferably, the one or more allulose enriched fractions independently of one another have a total content of impurities of at most 1.0 wt.-%, preferably at most 0.8 wt.-%, more preferably at most 0.6 wt.-%, yet more preferably at most 0.4 wt.-%, even more preferably at most 0.2 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

[0117] Preferably, the one or more allulose enriched fractions independently of one another have a glucose content of at most 3.0 wt.-%, preferably at most 2.0 wt.-%, more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

[0118] Preferably, the one or more allulose enriched fractions independently of one another have a sucrose content of at most 3.0 wt.-%, preferably at most 2.0 wt.-%, more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

[0119] Preferably, the one or more allulose enriched fractions independently of one another have a dry solids content of at least 4.0 wt.-%, preferably at least 6.0 wt.-%, more preferably at least 8.0 wt.-%, still more preferably at least 10 wt.-%, yet more preferably at least 12 wt.-%, even more preferably at least 14 wt.-%, most preferably at least 16 wt.-%, and in particular at least 18 wt.-%, relative to the total weight of the one or more allulose enriched fractions.

[0120] Preferably, the one or more allulose enriched fractions independently of one another have a content of hydroxymethyl furfural (HMF) of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions. Preferably, the one or more allulose enriched fractions independently of one another have 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 one or more allulose enriched fractions.

[0121] Preferably, the one or more allulose enriched fractions independently of one another have a content of 2,3 -butanedione of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions. Preferably, the one or more allulose enriched fractions independently of one another have 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 one or more allulose enriched fractions.

[0122] Preferably, the one or more allulose enriched fractions independently of one another have a content of acetaldehyde of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably atmost 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions. Preferably, the one or more allulose enriched fractions independently of one another have 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 one or more allulose enriched fractions.

[0123] Preferably, the one or more allulose enriched fractions independently of one another have a content of 2-keto-D-glucose of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions. Preferably, the one or more allulose enriched fractions independently of one another have 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 one or more allulose enriched fractions.

[0124] Preferably, the one or more allulose enriched fractions independently of one another have a content of allosone of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions. Preferably, the one or more allulose enriched fractions independently of one another have 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 one or more allulose enriched fractions.

[0125] Preferably, the one or more allulose enriched fractions independently of one another have a content of 3 -desoxyglucosone of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions. Preferably, the one or more allulose enriched fractions independently of one another have 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 one or more allulose enriched fractions.

[0126] Preferably, the fructose enriched fraction has a fructose content of at least 70.0 wt.-%, preferably at least 72.5 wt.-%, more preferably at least 75.0 wt.-%, yet more preferably at least 77.5 wt.-%, evenmore preferably at least 80.0 wt.-%, most preferably at least 82.5 wt.-%, and in particular at least 85.0 wt.-%, relative to the dry solids content of the fructose enriched fraction.

[0127] Preferably, the fructose enriched fraction has a fructose content of at least 87.5 wt.-%, preferably at least 90.0 wt.-%, more preferably at least 92.5 wt.-%, yet more preferably at least 95.0 wt.-%, even more preferably at least 97.5 wt.-%, most preferably at least 98.5 wt.-%, and in particular at least 99.0 wt.-%, relative to the dry solids content of the fructose enriched fraction.

[0128] Preferably, the fructose enriched fraction has an allulose content of at most 12.5 wt.-%, preferably at most 7.5 wt.-%, more preferably at most 5.0 wt.-%, yet more preferably at most 2.5 wt.-%, even more preferably at most 1.0 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction.

[0129] Preferably, the fructose enriched fraction has a total content of impurities of at most 4.5 wt.-%, preferably at most 4.0 wt.-%, 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.-%, relative to the dry solids content of the fructose enriched fraction.

[0130] Preferably, the fructose enriched fraction has a total content of impurities of at most 1.0 wt.-%, preferably at most 0.8 wt.-%, more preferably at most 0.6 wt.-%, yet more preferably at most 0.4 wt.- %, even more preferably at most 0.2 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction.

[0131] Preferably, the fructose enriched fraction has a glucose content of at most 3.0 wt.-%, preferably at most 2.0 wt.-%, more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction.

[0132] Preferably, the fructose enriched fraction has a sucrose content of at most 3.0 wt.-%, preferably at most 2.0 wt.-%, more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction.

[0133] Preferably, the fructose enriched fraction, preferably second purge fraction, has a dry solids content of at least 5.0 wt.-%, preferably at least 10 wt.-%, more preferably at least 15 wt.-%, still more preferably at least 20 wt.-%, yet more preferably at least 25 wt.-%, even more preferably at least 30 wt.- %, most preferably at least 35 wt.-%, and in particular at least 40 wt.-%, relative to the total weight of the fructose enriched fraction.

[0134] Preferably, the fructose enriched fraction has a content of hydroxymethyl furfural (HMF) of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the fructoseenriched fraction. Preferably, the fructose enriched fraction 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 fructose enriched fraction.

[0135] Preferably, the fructose enriched fraction has a content of 2,3-butanedione of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the fructose enriched fraction. Preferably, the fructose enriched fraction 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 fructose enriched fraction.

[0136] Preferably, the fructose enriched fraction has a content of acetaldehyde of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the fructose enriched fraction. Preferably, the fructose enriched fraction 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 fructose enriched fraction.

[0137] Preferably, the fructose enriched fraction has a content of 2-keto-D-glucose of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the fructose enriched fraction. Preferably, the fructose enriched fraction 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 fructose enriched fraction.

[0138] Preferably, the fructose enriched fraction has a content of allosone of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the fructose enriched fraction. Preferably, the fructose enriched fraction 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 atmost 200 ppmw, most preferably at most 100 ppmw, and in particular at most 50 ppmw, relative to the dry solids content of the fructose enriched fraction.

[0139] Preferably, the fructose enriched fraction has a content of 3 -desoxyglucosone of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 3,000 ppmw, most preferably at most 2,000 ppmw, and in particular at most 1,500 ppmw, relative to the dry solids content of the fructose enriched fraction. Preferably, the fructose enriched fraction 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 fructose enriched fraction.

[0140] It is contemplated that the purge fraction may have a total content of impurities that is higher than the total content of impurities of the one or more allulose enriched fractions.

[0141] It is contemplated that the purge fraction may have a total content of impurities that is higher than the total content of impurities of the fructose enriched fraction.

[0142] Preferably, the purge fraction has a total content of impurities of at least 0.001 wt.-%, preferably at least 0.01 wt.-%, more preferably at least 0.1 wt.-%, yet more preferably at least 0.5 wt.-%, even more preferably at least 1.0 wt.-%, most preferably at least 1.5 wt.-%, and in particular at least 2.0 wt.-%, relative to the dry solids content of the purge fraction.

[0143] Preferably, the purge fraction has an allulose content of at most 5.0 wt.-%, preferably at most 3.5 wt.-%, more preferably at most 2.0 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0. 1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the purge fraction.

[0144] Preferably, the purge fraction has a fructose content of at most 95 wt.-%, preferably at most 90 wt.-%, more preferably at most 85 wt.-%, yet more preferably at most 80 wt.-%, even more preferably at most 75 wt.-%, most preferably at most 70 wt.-%, and in particular at most 65 wt.-%, relative to the dry solids content of the purge fraction.

[0145] Preferably, the purge fraction has a fructose content of at most 5.0 wt.-%, preferably at most 3.5 wt.-%, more preferably at most 2.0 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the purge fraction.

[0146] Preferably, the purge fraction has a glucose content of at most 99 wt.-%, preferably at most 95 wt.-%, more preferably at most 90 wt.-%, yet more preferably at most 85 wt.-%, even more preferably at most 80 wt.-%, most preferably at most 75 wt.-%, and in particular at most 70 wt.-%, relative to the dry solids content of the purge fraction.

[0147] Preferably, the purge fraction has a sucrose content of at most 95 wt.-%, preferably at most 84 wt.-%, more preferably at most 73 wt.-%, yet more preferably at most 62 wt.-%, even more preferably at most 51 wt.-%, most preferably at most 40 wt.-%, and in particular at most 30 wt.-%, relative to the dry solids content of the purge fraction.

[0148] Preferably, the purge fraction, preferably first purge fraction, has a dry solids content of at least 4.0 wt.-%, preferably at least 6.0 wt.-%, more preferably at least 8.0 wt.-%, still more preferably at least 10 wt.-%, yet more preferably at least 12 wt.-%, even more preferably at least 14 wt.-%, most preferably at least 16 wt.-%, and in particular at least 18 wt.-%, relative to the total weight of the purge fraction.

[0149] Preferably, the purge fraction, preferably second purge fraction, has a dry solids content of at least 5.0 wt.-%, preferably at least 10 wt.-%, more preferably at least 15 wt.-%, still more preferably at least 20 wt.-%, yet more preferably at least 25 wt.-%, even more preferably at least 30 wt.-%, most preferably at least 35 wt.-%, and in particular at least 40 wt.-%, relative to the total weight of the purge fraction.

[0150] Preferably, the purge fraction has a content of hydroxymethyl furfural (HMF) of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

[0151] Preferably, the purge fraction has a content of 2,3 -butanedione of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

[0152] Preferably, the purge fraction has a content of acetaldehyde of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

[0153] Preferably, the purge fraction has a content of 2-keto-D-glucose of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

[0154] Preferably, the purge fraction has a content of allosone of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

[0155] Preferably, the purge fraction has a content of 3 -desoxyglucosone of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even morepreferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

[0156] In optional step (e) of the process according to the invention, the fructose enriched fraction obtained in step (d) is subjected to one or more concentration and / or purification measures thereby obtaining a concentrated and / or purified fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the concentrated and / or purified fructose enriched fraction.

[0157] Preferably, the one or more concentration and / or purification measures comprise a concentration; preferably reverse osmosis and / or evaporation.

[0158] Preferably, the one or more concentration and / or purification measures comprise a demineralization and / or a decoloration.

[0159] Suitable methods for demineralization are known to the skilled person and include but are not limited to ion exchange chromatography. Suitable ion exchange resins are commercially available.

[0160] Suitable methods for decoloration are likewise known to the skilled person and include but are not limited to adsorption. Suitable adsorbents such as active charcoal are commercially available.

[0161] In step (f) of the process according to the invention, the fructose enriched fraction obtained in step (d) or the concentrated and / or purified fructose enriched fraction obtained in optional step (e) is recirculated to step (a) or (b).

[0162] In preferred embodiments, the fructose enriched fraction or the concentrated and / or purified fructose enriched fraction is recirculated to step (a).

[0163] In other preferred embodiments, the fructose enriched fraction or the concentrated and / or purified fructose enriched fraction is recirculated to step (b).

[0164] In preferred embodiments, the process according to the invention additionally comprises the steps of(g) concentrating at least one of the one or more allulose enriched fractions thereby obtaining a concentrated allulose enriched fraction;(h) crystallizing allulose from the concentrated allulose enriched fraction thereby obtaining a suspension comprising or essentially consisting of allulose crystals and a liquid phase;(i) separating the allulose crystals and the liquid phase from one another; preferably by centrifugation; and(j) optionally, washing the allulose crystals thereby obtaining washed allulose crystals and a washing water.

[0165] In preferred embodiments, the process according to the invention additionally comprises the step of(k) recirculating the liquid phase to the crude product or the pre-purified product for subsequent chromatographic separation in step (d).

[0166] Preferably, step (d) comprises the sub-steps(di) chromatographically separating the crude product or the pre-purified product into (a) a first allulose enriched fraction and (P) an intermediate fraction enriched with (i) fructose as well as (ii) one or more impurities and / or glucose and / or sucrose;(d2) chromatographically separating the intermediate fraction into (a) a second allulose enriched fraction; ( ) the fructose enriched fraction; and (y) the purge fraction; and(ds) optionally, combining the first allulose enriched fraction and the second allulose enriched fraction with one another; and which additionally comprises the step of(k1) recirculating the liquid phase to the intermediate fraction for subsequent chromatographic separation in sub-step (ds).

[0167] In preferred embodiments, the process according to the invention additionally comprises the step of(1) recirculating the washing water to the at least one of the one or more allulose enriched fractions for subsequent concentration in step (g).

[0168] Another aspect of the invention relates to a process for the preparation of an allulose product comprising the steps of(a) providing a starting composition comprising (a) fructose and (P) optionally, one or more impurities and / or glucose and / or sucrose;(b) contacting the starting composition with an allulose-3 -epimerase to convert fructose into allulose thereby obtaining a crude product comprising (a) allulose, (P) fructose, and (y) one or more impurities and / or glucose and / or sucrose;(c) optionally, subjecting the crude product to one or more pre-purification measures thereby obtaining a pre-purified product comprising (a) allulose, (P) fructose, and (y) one or more impurities and / or glucose and / or sucrose;(d) chromatographically separating the crude product or the pre-purified product into(a) one or more allulose enriched fractions each having independently of one another an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction; and(P) a fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; wherein the fructose enriched fraction has atotal content of impurities of at most 1.0 wt.-%, preferably at most 0.8 wt.-%, more preferably at most 0.6 wt.-%, yet more preferably at most 0.4 wt.-%, even more preferably at most 0.2 wt.-%, most preferably at most 0. 1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction;(e) optionally, subjecting the fructose enriched fraction to one or more concentration and / or purification measures thereby obtaining a concentrated and / or purified fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the concentrated and / or purified fructose enriched fraction;(f) recirculating the fructose enriched fraction or the concentrated and / or purified fructose enriched fraction to step (a) or (b); wherein the one or more impurities are any organic compounds other than allulose, fructose, glucose, and sucrose; preferably wherein the one or more impurities comprise(i) allulose dimer, allulose-fructose disaccharide, allulose-glucose disaccharide, allulose tetramer, diallulose anhydride, levulinic acid, y-hydroxy valeric acid (GVA), furfural, hydroxymethyl furfural (HMF), 2,5-dimethylfiirane, 2,5-fiirane dicarboxylic acid (FDCA), 5 -hydroxymethyl furane 2-car- boxylic acid, 2,5-formyl furane carboxylic acid, 2,5-fiirane dialdehyde, 2,5-bis-(hydroxy-me- thyljfiirane, bis(5-formyl-2-fiirfiiryl)ether), fiirane-2-carboxylic acid, fiirane-3 -carboxylic acid, 5- hydroxyfiirfiiral, 2,5-dihydro-2,5-dimethoxyfiirane, (2R)-5 -oxotetrahydro-2 -furane carboxylic acid, bis(5 -methyl furfiiryljether, 5,5 '-methylene-di(furane-2 -carboxylic acid), or any combination thereof; and / or(ii) lactic acid, maltol, furaneol, allosone, glucosone, 1 -desoxyglucosone, 3 -desoxyglucosone, 3-des- oxygalactosone, formic acid, acetic acid, propionic acid, glyoxal, or any combination thereof; and / or(iii) 2,3-butanedione, acetaldehyde, 2-keto-D-glucose (glucosone), 3 -desoxyglucosone, or any combination thereof.

[0169] All preferred embodiments that have been described above with respect to the process according to the first aspect of the invention analogously apply to the process according to said another aspect of the invention and thus are not repeated hereinafter.

[0170] Figures 1 to 6 further illustrate the invention but are not to be construed as limiting its scope.

[0171] Figure 1 schematically illustrates a preferred embodiment of the invention involving one simulated moving bed chromatography providing three fractions. Fructose starting material, either crystalline or syrup, from fructose storage tank (1) and demineralized water (2) are preferably supplied to mixing unit (3) and after mixing, preferably to pH-adjustment / demineralization unit (4). The thus preparedstarting composition is preferably supplied to enzyme reactor with ultrafiltration unit (5), wherein the starting composition is contacted with an allulose-3 -epimerase to convert fructose into allulose thereby obtaining a crude product comprising allulose and residual, i.e. not converted fructose. The crude product additionally comprises one or more of one or more impurities and / or glucose and / or sucrose which may originate from various sources, especially from recirculation. After ultrafiltration, the crude reaction product is preferably pre-purified in first demineralization / decoloring unit (6) and the thus obtained pre-purified product is preferably supplied to simulated moving bed chromatography unit (7).

[0172] Simulated moving bed chromatography preferably provides three process streams: (i) a fructose enriched fraction that is preferably supplied to first concentration unit (8); (ii) an allulose enriched fraction that is preferably supplied to second concentration unit (11); and (iii) a purge fraction that is preferably disposed as purge (10).

[0173] The fructose enriched fraction is preferably concentrated in first concentration unit (8), e.g. by reverse osmosis and / or evaporation, and subsequently, preferably supplied to second demineralization / decoloring unit (9) before the thus obtained concentrated and / or purified fructose enriched fraction is preferably recirculated to mixing unit (3). One or more impurities and / or glucose and / or sucrose that may have been present and / or that may have been produced in the course of enzymatic conversion and / or subsequent work-up measures and that may not have been completely separated from the fructose enriched fraction by simulated moving bed chromatography are thus recirculated to mixing unit (3) as well. This is one possible source, among others, for the presence of one or more impurities and / or glucose and / or sucrose in the crude product.

[0174] The work-up of the allulose enriched fraction depends upon the nature of the desired allulose product.

[0175] When the allulose product is an allulose syrup, the allulose enriched fraction is preferably decolored in decoloring unit (12) and subsequently, preferably sterile filtrated in sterile filtration unit (13). At this stage, the quality of the allulose product may be controlled at first critical control point (14) before the allulose syrup is preferably stored in syrup storage tank (15).

[0176] When the allulose product is a solid, preferably at least partially crystalline material, the allulose enriched fraction is preferably further concentrated in third concentration unit (16) in preparation of subsequent crystallization in crystallization unit (17). The suspension leaving the crystallization unit (17) comprises or essentially consists of allulose crystals and a liquid phase, which are preferably separated from one another by centrifugation in centrifugation unit (18). The thus obtained liquid phase is preferably recirculated to the pre-purified product for subsequent chromatographic separation in simulated moving bed chromatography unit (7). This is another possible source, among others, for the presence of one or more impurities and / or glucose and / or sucrose in the crude product after recirculation of the fructose enriched fraction. The thus obtained allulose crystals are preferably washed with demineralized water thereby obtaining washed allulose crystals and a washing water. The washing water ispreferably recirculated either to third concentration unit (16) or second concentration unit (11). This is a further possible source, among others, for the presence of one or more impurities and / or glucose and / or sucrose in the crude product after recirculation of the fructose enriched fraction. The thus obtained washed allulose crystals are preferably dried in drying unit (19). At this stage, the quality of the allulose product may be controlled at second critical control point (20) before the allulose crystals are preferably stored in crystalline product storage tank (21).

[0177] Figure 2 schematically illustrates another preferred embodiment of the invention involving a first simulated moving bed chromatography providing two fractions and a subsequent second simulated moving bed chromatography providing three fractions.

[0178] Deviating from the embodiment illustrated in Figure 1, according to the embodiment illustrated in Figure 2 the pre-purified product leaving first demineralization / decoloring unit (6) is supplied to first simulated moving bed chromatography unit (7) which preferably provides two process streams: (i) an intermediate fraction enriched with (i) fructose as well as (ii) one or more impurities and / or glucose and / or sucrose that is preferably supplied to second simulated moving bed chromatography unit (22); and (ii) a first allulose enriched fraction that is preferably supplied to second concentration unit (11). The second simulated moving bed chromatography unit (22) preferably provides three process streams: (i) a fructose enriched fraction that is preferably supplied to first concentration unit (8); (ii) a second allulose enriched fraction that is preferably also supplied to second concentration unit (11) where it is preferably combined with the first allulose enriched fraction provided by the first simulated moving bed chromatography unit (7); and (iii) a purge fraction that is preferably disposed as purge (10).

[0179] Alternatively, not shown in Figure 2, the first simulated moving bed chromatography unit (7) may provide a third process stream, namely another purge fraction.

[0180] Further deviating from the embodiment illustrated in Figure 1, according to the embodiment illustrated in Figure 2 the liquid phase obtained by centrifugation in centrifugation unit (18) is preferably recirculated to the intermediate fraction for subsequent chromatographic separation in second simulated moving bed chromatography unit (22).

[0181] Figure 3 schematically illustrates the working principle of a simulated moving bed (SMB) chromatography according to the invention comprising e.g. four zones I through IV. The zones are separated from one another by valves that are individually regulated in order to simulate the moving of the solid bed (stationary phase) in countercurrent direction to the flow of the fluid (liquid phase).

[0182] The chamber volume, especially the chamber volume of zones II and III, is an important parameter that is advantageously adjusted in order to optimize efficiency of the chromatography.

[0183] A liquid feed comprising allulose and fructose, i.e. the crude product or the pre-purified product, is fed into the system between zones II and III. Water is introduced as fresh liquid eluent into zone I. The ratio of the volume of water to the volume of feed, i.e. the water to feed ratio, is another importantparameter that is advantageously adjusted in order to optimize efficiency of the chromatography. The lower the water to feed ratio, the more concentrated to solutions that are chromatographically separated from one another (i.e. the higher their solids content) and the lower the energy consumption for subsequent water evaporation.

[0184] Raffinate, i.e. a fructose enriched fraction orthe intermediate fraction, respectively, is withdrawn between zones III and IV, whereas extract, i.e. an allulose enriched fraction, is withdrawn between zones I and II. The ratio of the volume of the extract (product) to the volume of the raffinate, i.e. the extract to raffinate ratio, is a further important parameter that is advantageously adjusted in order to optimize efficiency of the chromatography.

[0185] Chamber volume, especially of zones II and III, water to feed ratio (v / v), and extract to raffinate ratio (v / v) are interrelated and can be optimized in order to provide- an allulose enriched fraction (extract) with a high purity of allulose, a high recovery of allulose, and a high solids content; as well as- a fructose enriched fraction (raffinate) with a low content of allulose and a high solids content.

[0186] Figure 4 is an elution profile of a sequential simulated moving bed (SSMB) chromatography of Example 1.

[0187] Figure 5 schematically illustrates the influence of chamber volume of zone I (Cl), chamber volume of zone IV (C4), water to feed ratio (W / F), and extract (product) to raffinate ratio (P / R) on the chromatographic separation, whereas large font indicates an increase and small font indicates a decrease of the respective parameter, and the arrow indicates the direction of the change of the graph for the respective parameter.

[0188] Figure 6 is a summarized plot of an evaluation of Example 2.

[0189] List of reference numerals:1 : fructose storage tank2: demineralized water3 : mixing unit4: pH-adjustment / demineralization unit5 : enzyme reactor with ultrafiltration unit6: first demineralization / decoloring unit7 : first simulated moving bed chromatography unit8: first concentration unit9: second demineralization / decoloring unit10: purge11 : second concentration unit12: decoloring unit13: sterile filtration unit14: first critical control point15: syrup storage tank16: third concentration unit17: crystallization unit18: centrifugation unit19: drying unit20: second critical control point21 : crystalline product storage tank22: second simulated moving bed chromatography unit

[0190] The following examples further illustrate the invention but are not to be construed as limiting its scope.

[0191] Example 1 - SSMB with two separation fractions:

[0192] Fructose was converted into allulose under enzymatic catalysis by an allulose-3-epimerase. The thus obtained crude product was subjected to pre-purification measures thereby obtaining a pre-purified product having the following composition (HPLC according to ICUMSA GS3-50):

[0193] In a sequential simulated moving bed (SSMB) with two separation fractions, the above prepurified product was chromatographically separated into a raffinate cut (fructose enriched fraction) and an extract cut (allulose enriched fraction).

[0194] The results are illustrated in Figure 4.

[0195] As demonstrated, in an SSMB with two separation fractions, only a partial separation takes place. The peaks of the main components fructose and allulose run into each other and meaningful material flow cuts (raffinate cut and extract cut) are made. A balanced mass balance means that the sum of all input mass flows is equal to the sum of all output mass flows. For the SSMB, this means that unwanted components (sucrose, glucose, impurities) must also leave an SSMB either via the raffinate route (fructose enriched fraction) or the extract route (allulose enriched fraction). No ideal separation of unwanted components can be achieved, as can already be seen with the fructose and allulose components.

[0196] Example 2 - evaluation of the possibility of a third separation fraction:

[0197] A test run was carried out to evaluate the possibility of a third cut. For this purpose, the raffinate cut (fructose enriched fraction) was divided into 10 evenly spaced measurement times. The 10 samples of the raffinate cut (fructose enriched fraction) and one sample of the feed were analyzed (HPLC according to ICUMSA GS3-50) in order to determine the absolute contents of the components.

[0198] The evaluation of the absolute contents was weighted with reference to the absolute mass flows of the feed flow and the raffinate flow.

[0199] A summarized plot of this evaluation is shown in Figure 6.

[0200] For glucose and sucrose, it can be seen that at the end of the entire raffinate fraction, the % mass fraction in relation to the feed exceeds 100 %. A value of 110.7 % is reached for sucrose and 103.8 % for glucose. There are two reasons for this. Firstly, the measured concentrations for sucrose and glucose are in the range of the lower limit of quantification and naturally exhibit imprecision. Secondly, the mass balance of a continuously operated SSMB is almost never completely balanced. Slight flow rate fluctuations and inhomogeneities in the separation column always lead to mass balance fluctuations. A mass balance of 100% + / -5% is usually considered to be balanced. This is already the case for glucose; sucrose is slightly higher. However, this does not change the trend and general significance of the results.

[0201] As demonstrated, unwanted components having retention times shorter than that of fructose tend to be found in the raffinate cut (fructose enriched fraction). As shown in Figure 6, slightly more than 100 % of the glucose and sucrose from the feed can be recovered at the end of the raffinate cut (fructose enriched fraction). The recovery of these unwanted components is also consistently higher than that of fructose. The opposite is true for allulose, where the recovery of allulose is consistently lower than that of fructose. This means that the allulose peak is downstream of the fructose peak. The superposition of fructose and allulose takes place at high concentrations of one or the other component.

[0202] Consequently, a separation of components having retention times between allulose and fructose would always be accompanied by high concentrations of allulose and fructose. A cut in this area will therefore generally be uneconomical.

[0203] The situation is different, however, if a fraction is separated that contains a higher proportion of sucrose and glucose, i.e. components that precede fructose. These are consistently higher in mass proportion in relation to the feed than fructose.

[0204] Fructose loss can be minimized when a third separation fraction is cut at the beginning of the raffinate cut (fructose enriched fraction). When an unwanted component is accumulated in the system, the cut should be selected so that the formation of such unwanted component or the addition of this unwanted component to the system corresponds exactly to the quantity of the third cut. In this way, accumulation is stopped, but at the same time it must be accepted that a certain amount of fructose will also be lost.

[0205] Example 3 - two SSMBs each with a third separation fraction:

[0206] In order to prevent the accumulation of glucose and sucrose, a concept is selected in which a second SSMB is required and a classic purge is carried out at the same time.

[0207] A mass balance of the main streams to prevent the accumulation of sucrose and glucose and the resulting losses of fructose and allulose was determined. In continuous operation, a mass flow of 0.7 kg / h of sucrose and 1.7 kg / h of glucose must be discharged. The realization via a second SSMB and purge streams ultimately results in an unavoidable loss flow of 54.2 kg / h fructose and 1.7 kg / h allulose:

[0208] Example 4 - single SSMB with a third separation fraction:

[0209] When the same amount of sucrose and glucose is to be discharged via a single SSMB with a third separation fraction, it can be shown mathematically that approximately 3.3% must be discharged as a third separation fraction at the beginning of the raffinate cut (fructose enriched fraction). In this case, 0.7 kg / h of sucrose and 1.7 kg / h of glucose would be discharged. However, the loss flow here is only 31.5 kg / h fructose and 1.2 kg / h allulose:

[0210] The establishment of a third separation fraction, which is realized by discharging the first 3.3% of the raffinate cut as the third separation fraction, thus effectively prevents the accumulation of undesirable components. At the same time, the loss of fructose is reduced by about 40% compared to the concept of Example 3 and the loss of allulose is still reduced by about 30%. In addition, a second SSMB can be dispensed with, saving investment and operating costs:

[0211] The feasibility of a third separation fraction in an SSMB for the separation of unwanted components has been demonstrated. In addition, realization of a third separation fraction is the moreeconomical alternative in terms of raw material costs, investment and operating costs compared to a classic "purge" or an additional SSMB. Furthermore, for the separation of components with a shorter retention time than fructose, a third separation fraction can be operated economically.

[0212] The allulose process also reveals unwanted components having retention times downstream of allulose. These unwanted components can also be separated by a third separation fraction. In this case, the principle is completely analogous to the raffinate cut (fructose enriched fraction), but only takes place at the end of the extract cut (allulose enriched fraction).

[0213] For components having retention times between fructose and allulose, however, a third separation fraction is not expected to be economically viable. The losses of fructose and allulose would be too high due to the high concentrations in this area.

Claims

Patent claims:

1. A process for the preparation of an allulose product comprising the steps of(a) providing a starting composition comprising(a) fructose and(P) optionally, one or more impurities and / or glucose and / or sucrose;(b) contacting the starting composition with an allulose-3 -epimerase to convert fructose into allulose thereby obtaining a crude product comprising(a) allulose,(P) fructose, and(y) one or more impurities and / or glucose and / or sucrose;(c) optionally, subjecting the crude product to one or more pre-purification measures thereby obtaining a pre-purified product comprising(a) allulose,(P) fructose, and(y) one or more impurities and / or glucose and / or sucrose;(d) chromatographically separating the crude product or the pre-purified product into(a) one or more allulose enriched fractions each having independently of one another an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction;(P) a fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; and(y) optionally, a purge fraction enriched with one or more impurities and / or glucose and / or sucrose;(e) optionally, subjecting the fructose enriched fraction to one or more concentration and / or purification measures thereby obtaining a concentrated and / or purified fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the concentrated and / or purified fructose enriched fraction;(f) recirculating the fructose enriched fraction or the concentrated and / or purified fructose enriched fraction to step (a) or (b); wherein the one or more impurities are any organic compounds other than allulose, fructose, glucose, and sucrose.

2. The process according to claim 1, wherein in step (d) the crude product or the pre-purified product is chromatographically separated into(a) one or more allulose enriched fractions each having independently of one another an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction;(P) a fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; and(y) a purge fraction enriched with one or more impurities and / or glucose and / or sucrose.

3. The process according to claim 1 or 2, wherein the allulose product is solid, preferably at least partially crystalline.

4. The process according to claim 1 or 2, wherein the allulose product is liquid, preferably a syrup.

5. The process according to any of the preceding claims, wherein the starting composition has a fructose content of at least 40 wt.-%, preferably at least 60 wt.-%, more preferably at least 70 wt.- %, yet more preferably at least 80 wt.-%, even more preferably at least 90 wt.-%, most preferably at least 95 wt.-%, and in particular at least 98 wt.-%, relative to the dry solids content of the starting composition.

6. The process according to any of the preceding claims, wherein the starting composition comprises glucose.

7. The process according to claim 6, wherein the starting composition has a glucose content of at most 8.0 wt.-%, preferably at most 7.0 wt.-%, more preferably at most 6.0 wt.-%, yet more preferably at most 5.0 wt.-%, even more preferably at most 4.0 wt.-%, most preferably at most 3.0 wt.-%, and in particular at most 2.0 wt.-%, relative to the dry solids content of the starting composition.

8. The process according to claim 6 or 7, wherein the starting composition has a glucose content of at least 0.0001 wt.-%, preferably at least 0.001 wt.-%, more preferably at least 0.01 wt.-%, yet more preferably at least 0.1 wt.-%, even more preferably at least 0.2 wt.-%, most preferably at least 0.3 wt.-%, and in particular at least 0.4 wt.-%, relative to the dry solids content of the starting composition.

9. The process according to any of the preceding claims, wherein the starting composition comprises sucrose.

10. The process according to claim 9, wherein the starting composition has a sucrose content of at most 1.8 wt.-%, preferably at most 1.6 wt.-%, more preferably at most 1.4 wt.-%, yet morepreferably at most 1.2 wt.-%, even more preferably at most 1.0 wt.-%, most preferably at most 0.8 wt.-%, and in particular at most 0.6 wt.-%, relative to the dry solids content of the starting composition.

11. The process according to any of the preceding claims, wherein at least one of the one or more impurities is formed in step (b).

12. The process according to any of the preceding claims, wherein at least one of the one or more impurities is formed in one or more steps subsequent to step (b).

13. The process according to any of the preceding claims, wherein the one or more impurities comprise allulose dimer, allulose-fructose disaccharide, allulose-glucose disaccharide, allulose tetramer, diallulose anhydride, levulinic acid, y-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-(hy- droxy-methyl)furane, bis(5-formyl-2-furfuryl)ether), furane-2-carboxylic acid, furane-3 -carboxylic acid, 5 -hydroxyfurfural, 2,5-dihydro-2,5-dimethoxyfurane, (2R)-5-oxotetrahydro-2-furane carboxylic acid, bis(5-methyl furfuryl)ether, 5, 5'-methylene-di(furane-2 -carboxylic acid), or any combination thereof.

14. The process according to any of the preceding claims, wherein the one or more impurities comprise lactic acid, maltol, furaneol, allosone, glucosone (2-keto-D-glucose), 1 -desoxyglucosone, 3- desoxyglucosone, 3 -desoxygalactosone, formic acid, acetic acid, propionic acid, glyoxal, or any combination thereof.

15. The process according to any of the preceding claims, wherein the one or more impurities comprise 2,3-butanedione, acetaldehyde, 2-keto-D-glucose (glucosone), 3 -desoxyglucosone, or any combination thereof.

16. The process according to any of the preceding claims, wherein the crude product has a total content of impurities of at least 0.0001 wt.-%, preferably at least 0.001 wt.-%, more preferably at least 0.01 wt.-%, yet more preferably at least 0. 1 wt.-%, even more preferably at least 0.2 wt.-%, most preferably at least 0.3 wt.-%, and in particular at least 0.5 wt.-%, relative to the dry solids content of the crude product.

17. The process according to any of the preceding claims, wherein the crude product has a total content of impurities of at most 7.0 wt.-%, preferably at most 6.0 wt.-%, more preferably at most 5.0wt.-%, yet more preferably at most 4.0 wt.-%, even more preferably at most 3.0 wt.-%, most preferably at most 2.0 wt.-%, and in particular at most 1.0 wt.-%, relative to the dry solids content of the crude product.

18. The process according to any of the preceding claims, wherein the crude product has an allulose content of at least 15 wt.-%, preferably at least 23 wt.-%, more preferably at least 32 wt.-%, yet more preferably at least 40 wt.-%, even more preferably at least 48 wt.-%, most preferably at least 57 wt.-%, and in particular at least 65 wt.-%, relative to the dry solids content of the crude product.

19. The process according to any of the preceding claims, wherein the crude product has a fructose content of at most 85 wt.-%, preferably at most 77 wt.-%, more preferably at most 68 wt.-%, yet more preferably at most 60 wt.-%, even more preferably at most 52 wt.-%, most preferably at most 44 wt.-%, and in particular at most 35 wt.-%, relative to the dry solids content of the crude product.

20. The process according to any of the preceding claims, wherein the crude product has a glucose content of at most 8.0 wt.-%, preferably at most 7.0 wt.-%, more preferably at most 6.0 wt.-%, yet more preferably at most 5.0 wt.-%, even more preferably at most 4.0 wt.-%, most preferably at most 3.0 wt.-%, and in particular at most 2.0 wt.-%, relative to the dry solids content of the crude product.

21. The process according to any of the preceding claims, wherein the crude product has a sucrose content of at most 5.00 wt.-%, preferably at most 4.25 wt.-%, more preferably at most 3.50 wt.- %, yet more preferably at most 2.75 wt.-%, even more preferably at most 2.00 wt.-%, most preferably at most 1.25 wt.-%, and in particular at most 0.50 wt.-%, relative to the dry solids content of the crude product.

22. The process according to any of the preceding claims, wherein the crude product 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 crude product.

23. The process according to any of the preceding claims, wherein the crude product 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 2,000ppmw, most preferably 1 to 1,000 ppmw, and in particular 1 to 500 ppmw, relative to the dry solids content of the crude product.

24. The process according to any of the preceding claims, wherein the crude product 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 crude product.

25. The process according to any of the preceding claims, wherein the crude product has a content of2-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 crude product.

26. The process according to any of the preceding claims, wherein the crude product 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 crude product.

27. The process according to any of the preceding claims, wherein the crude product has a content of3 -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 crude product.

28. The process according to any of the preceding claims, wherein the one or more pre-purification measures comprise a filtration, preferably an ultrafiltration.

29. The process according to any of the preceding claims, wherein the one or more pre-purification measures comprise a demineralization and / or a decoloration.

30. The process according to any of the preceding claims, wherein chromatographic separation in step (d) provides- one or more allulose enriched fractions, wherein relative to the dry solids content of the one or more allulose enriched fractions, the content of allulose is within the range of from 90 to100 wt.-%, the content of fructose is within the range of from 0 to 5 wt.-% (50000 ppmw), and the content of glucose is within the range of from 0 to 0.5 wt.-% (5000 ppmw);- a fructose enriched fraction, wherein relative to the dry solids content of the fructose enriched fraction, the content of fructose is within the range of from 90 to 100 wt.-%, the content of allulose is within the range of from 0 to 5 wt.-% (50000 ppmw), and the content of glucose is within the range of from 0 to 1.5 wt.-% (15000 ppmw).

31. The process according to any of the preceding claims, wherein chromatographic separation comprises at least one simulated moving bed chromatography (SMB), preferably at least one sequential simulated moving bed chromatography (SSMB).

32. The process according to claim 31, wherein the water to feed ratio (v / v) of the SMB is at most 4.0, more preferably at most 3.7, still more preferably at most 3.4, yet more preferably at most 3.1, even more preferably at most 2.8, most preferably at most 2.5, and in particular at most 2.2.

33. The process according to claim 31 or 32, wherein the water to feed ratio (v / v) of the SMB is at least 0.8, more preferably at least 0.9, still more preferably at least 1.0, yet more preferably at least 1.1, even more preferably at least 1.2, most preferably at least 1.3, and in particular at least 1.4.

34. The process according to any of claims 31 to 33, wherein the extract to raffinate ratio (v / v) of the SMB is at most 1.6, more preferably at most 1.5, still more preferably at most 1.4, yet more preferably at most 1.3, even more preferably at most 1.2, most preferably at most 1.1, and in particular at most 1.0.

35. The process according to any of claims 31 to 34, wherein the extract to raffinate ratio (v / v) of the SMB is 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.

36. The process according to any of claims 31 to 35, wherein the purity of allulose in the extract, i.e. in the allulose enriched fraction, is at least 93%, more preferably at least 94%, still more preferably at least 95%, yet more preferably at least 96%, even more preferably at least 97%, most preferably at least 98%, and in particular at least 99%.

37. The process according to any of claims 31 to 36, wherein the recovery of allulose is at least 79%, more preferably at least 80%, still more preferably at least 81%, yet more preferably at least 82%,even more preferably at least 83%, most preferably at least 84%, and in particular at least 85%.; preferably wherein the recovery of allulose is at least 86%, more preferably at least 87%, still more preferably at least 88%, yet more preferably at least 89%, even more preferably at least 90%, most preferably at least 91%, and in particular at least 92%.

38. The process according to any of claims 31 to 37, wherein the recovery of allulose is at least 93%, more preferably at least 94%, still more preferably at least 95%, yet more preferably at least 96%, even more preferably at least 97%, most preferably at least 98%, and in particular at least 99%.

39. The process according to any of the preceding claims, which includes a single simulated moving bed (SMB) chromatography, preferably a single sequential simulated moving bed chromatography (SSMB).

40. The process according to any of the preceding claims, wherein in step (d) the crude product obtained in step (b) or the pre-purified product obtained in optional step (c) is then chromatograph- ically separated into(a) an allulose enriched fraction having an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction;(P) a fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; and(y) a purge fraction enriched with one or more impurities and / or glucose and / or sucrose.

41. The process according to claim 40, wherein in flow direction of the crude product obtained in step(b) or the pre-purified product obtained in optional step (c), the allulose enriched fraction is separated downstream of the fructose enriched fraction.

42. The process according to claim 40 or 41, wherein the purge fraction is chromatographically separated upstream of the fructose enriched fraction, and the allulose enriched fraction is separated downstream of the fructose enriched fraction.

43. The process according to any of claims 40 to 42, wherein the fructose enriched fraction is chromatographically separated upstream of the allulose enriched fraction, and the purge fraction is separated downstream of the allulose enriched fraction.

44. The process according to any of claims 40 to 43, wherein a first purge fraction is chromatographically separated upstream of the fructose enriched fraction, the allulose enriched fraction isseparated downstream of the fructose enriched fraction, and a second purge fraction is separated downstream of the allulose enriched fraction.

45. The process according to any of claims 40 to 44, wherein a purge fraction is separated upstream of the fructose enriched fraction and the flow of the purge fraction amounts to at most 9.0 wt.-% of the flow of the fructose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.- %, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

46. The process according to any of claims 40 to 45, wherein a purge fraction is separated downstream of the allulose enriched fraction and the flow of the purge fraction amounts to at most 9.0 wt.-% of the flow of the allulose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

47. The process according to any of claims 1 to 38, which includes two simulated moving bed (SMB) chromatographies, preferably two sequential simulated moving bed chromatographies (SSMB).

48. The process according to any of the preceding claims, wherein step (d) comprises the sub-steps(di) chromatographically separating the crude product or the pre-purified product into(a) a first allulose enriched fraction and(P) an intermediate fraction enriched with (i) fructose as well as (ii) one or more impurities and / or glucose and / or sucrose;(d2) chromatographically separating the intermediate fraction into(a) a second allulose enriched fraction;(P) the fructose enriched fraction; and(y) the purge fraction; and(ds) optionally, combining the first allulose enriched fraction and the second allulose enriched fraction with one another.

49. The process according to claim 48, wherein in flow direction of the crude product obtained in step (b) or the pre-purified product obtained in optional step (c), in sub-step (di) the first allulose enriched fraction is separated downstream of the intermediate fraction.

50. The process according to claim 48 or 49, wherein the purge fraction is chromatographically separated upstream of the intermediate fraction, and the first allulose enriched fraction is separated downstream of the intermediate fraction.

51. The process according to any of claims 48 to 50, wherein the intermediate fraction is chromato- graphically separated upstream of the first allulose enriched fraction, and the purge fraction is separated downstream of the first allulose enriched fraction.

52. The process according to any of claims 48 to 51, wherein a first purge fraction is chromatograph- ically separated upstream of the intermediate fraction, the first allulose enriched fraction is separated downstream of the intermediate fraction, and a second purge fraction is separated downstream of the first allulose enriched fraction.

53. The process according to any of claims 48 to 52, wherein a purge fraction is separated upstream of the intermediate fraction and the flow of the purge fraction amounts to at most 9.0 wt.-% of the flow of the intermediate fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

54. The process according to any of claims 48 to 53, wherein a purge fraction is separated downstream of the first allulose enriched fraction and the flow of the purge fraction amounts to at most 9.0 wt.-% of the flow of the first allulose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

55. The process according to any of claims 48 to 54, wherein in flow direction of the crude product obtained in step (b) or the pre-purified product obtained in optional step (c), in sub-step (d2) the second allulose enriched fraction is separated downstream of the fructose enriched fraction.

56. The process according to any of claims 48 to 55, wherein the purge fraction is chromatograph- ically separated upstream of the fructose enriched fraction, and the second allulose enriched fraction is separated downstream of the fructose enriched fraction.

57. The process according to any of claims 48 to 56, wherein the fructose enriched fraction is chro- matographically separated upstream of the second allulose enriched fraction, and the purge fraction is separated downstream of the second allulose enriched fraction.

58. The process according to any of claims 48 to 57, wherein a first purge fraction is chromatograph- ically separated upstream of the fructose enriched fraction, the second allulose enriched fractionis separated downstream of the fructose enriched fraction, and a second purge fraction is separated downstream of the second allulose enriched fraction.

59. The process according to any of claims 48 to 58, wherein a purge fraction is separated upstream of the fructose enriched fraction and the flow of the purge fraction amounts to at most 9.0 wt.-% of the flow of the fructose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.- %, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

60. The process according to any of claims 48 to 59, wherein a purge fraction is separated downstream of the second allulose enriched fraction and the flow of the purge fraction amounts to at most 9.0 wt.-% of the flow of the second allulose enriched fraction, preferably at most 8.0 wt.-%, still more preferably at most 7.0 wt.-%, yet more preferably at most 6.0 wt.-%, even more preferably at most 5.0 wt.-%, most preferably at most 4.0 wt.-%, and in particular at most 3.0 wt.-%.

61. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have an allulose content of at least 87.5 wt.-%, preferably at least 90.0 wt.-%, more preferably at least 92.5 wt.-%, yet more preferably at least 95.0 wt.-%, even more preferably at least 97.5 wt.-%, most preferably at least 98.5 wt.-%, and in particular at least 99.0 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

62. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a fructose content of at most 12.5 wt.-%, preferably at most 7.5 wt.-%, more preferably at most 5.0 wt.-%, yet more preferably at most 2.5 wt.-%, even more preferably at most 1.0 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

63. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a total content of impurities of at most 2.0 wt.-%, preferably at most 1.8 wt.-%, more preferably at most 1.6 wt.-%, still more preferably at most 1.4 wt.-%, and yet more preferably at most 1.2 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

64. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a total content of impurities of at most 1.0 wt.-%, preferably at most 0.8 wt.-%, more preferably at most 0.6 wt.-%, yet more preferably at most 0.4 wt.-%, even more preferably at most 0.2 wt.-%, most preferably at most 0.1 wt.-%, and inparticular at most 0.01 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

65. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a glucose content of at most 3.0 wt.-%, preferably at most 2.0 wt.-%, more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

66. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a sucrose content of at most 3.0 wt.-%, preferably at most 2.0 wt.-%, more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the one or more allulose enriched fractions.

67. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a dry solids content of at least 4.0 wt.-%, preferably at least 6.0 wt.-%, more preferably at least 8.0 wt.-%, still more preferably at least 10 wt.-%, yet more preferably at least 12 wt.-%, even more preferably at least 14 wt.-%, most preferably at least 16 wt.-%, and in particular at least 18 wt.-%, relative to the total weight of the one or more allulose enriched fractions.

68. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a content of hydroxymethyl furfural (HMF) of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions.

69. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a content of 2, 3 -butanedione of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions.

70. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a content of acetaldehyde of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions.

71. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a content of 2-keto-D-glucose of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions.

72. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a content of allosone of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions.

73. The process according to any of the preceding claims, wherein the one or more allulose enriched fractions independently of one another have a content of 3 -desoxyglucosone of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the one or more allulose enriched fractions.

74. The process according to any of the preceding claims, wherein the fructose enriched fraction has a fructose content of at least 70.0 wt.-%, preferably at least 72.5 wt.-%, more preferably at least 75.0 wt.-%, yet more preferably at least 77.5 wt.-%, even more preferably at least 80.0 wt.-%, most preferably at least 82.5 wt.-%, and in particular at least 85.0 wt.-%, relative to the dry solids content of the fructose enriched fraction.

75. The process according to any of the preceding claims, wherein the fructose enriched fraction has a fructose content of at least 87.5 wt.-%, preferably at least 90.0 wt.-%, more preferably at least 92.5 wt.-%, yet more preferably at least 95.0 wt.-%, even more preferably at least 97.5 wt.-%,most preferably at least 98.5 wt.-%, and in particular at least 99.0 wt.-%, relative to the dry solids content of the fructose enriched fraction.

76. The process according to any of the preceding claims, wherein the fructose enriched fraction has an allulose content of at most 12.5 wt.-%, preferably at most 7.5 wt.-%, more preferably at most 5.0 wt.-%, yet more preferably at most 2.5 wt.-%, even more preferably at most 1.0 wt.-%, most preferably at most 0. 1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction.

77. The process according to any of the preceding claims, wherein the fructose enriched fraction has a total content of impurities of at most 4.5 wt.-%, preferably at most 4.0 wt.-%, 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.-%, relative to the dry solids content of the fructose enriched fraction.

78. The process according to any of the preceding claims, wherein the fructose enriched fraction has a total content of impurities of at most 1.0 wt.-%, preferably at most 0.8 wt.-%, more preferably at most 0.6 wt.-%, yet more preferably at most 0.4 wt.-%, even more preferably at most 0.2 wt.- %, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction.

79. The process according to any of the preceding claims, wherein the fructose enriched fraction has a glucose content of at most 3.0 wt.-%, preferably at most 2.0 wt.-%, more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction.

80. The process according to any of the preceding claims, wherein the fructose enriched fraction has a sucrose content of at most 3.0 wt.-%, preferably at most 2.0 wt.-%, more preferably at most 1.5 wt.-%, yet more preferably at most 1.0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0. 1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction.

81. The process according to any of the preceding claims, wherein the fructose enriched fraction, preferably second purge fraction, has a dry solids content of at least 5.0 wt.-%, preferably at least 10 wt.-%, more preferably at least 15 wt.-%, still more preferably at least 20 wt.-%, yet more preferably at least 25 wt.-%, even more preferably at least 30 wt.-%, most preferably at least 35wt.-%, and in particular at least 40 wt.-%, relative to the total weight of the fructose enriched fraction.

82. The process according to any of the preceding claims, wherein the fructose enriched fraction has a content of hydroxymethyl furfural (HMF) of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the fructose enriched fraction.

83. The process according to any of the preceding claims, wherein the fructose enriched fraction has a content of 2,3 -butanedione of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the fructose enriched fraction.

84. The process according to any of the preceding claims, wherein the fructose enriched fraction has a content of acetaldehyde of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the fructose enriched fraction.

85. The process according to any of the preceding claims, wherein the fructose enriched fraction has a content of 2-keto-D-glucose of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the fructose enriched fraction.

86. The process according to any of the preceding claims, wherein the fructose enriched fraction has a content of allosone of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferably at most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the fructose enriched fraction.

87. The process according to any of the preceding claims, wherein the fructose enriched fraction has a content of 3 -desoxyglucosone of at most 10,000 ppmw, preferably at most 8,000 ppmw, more preferably at most 6,000 ppmw, yet more preferably at most 4,000 ppmw, even more preferablyat most 2,000 ppmw, most preferably at most 1,000 ppmw, and in particular at most 500 ppmw, relative to the dry solids content of the fructose enriched fraction.

88. The process according to any of the preceding claims, wherein the purge fraction has a total content of impurities that is higher than the total content of impurities of the one or more allulose enriched fractions.

89. The process according to any of the preceding claims, wherein the purge fraction has a total content of impurities that is higher than the total content of impurities of the fructose enriched fraction.

90. The process according to any of the preceding claims, wherein the purge fraction has a total content of impurities of at least 0.001 wt.-%, preferably at least 0.01 wt.-%, more preferably at least 0.1 wt.-%, yet more preferably at least 0.5 wt.-%, even more preferably at least 1.0 wt.-%, most preferably at least 1.5 wt.-%, and in particular at least 2.0 wt.-%, relative to the dry solids content of the purge fraction.

91. The process according to any of the preceding claims, wherein the purge fraction has an allulose content of at most 5.0 wt.-%, preferably at most 3.5 wt.-%, more preferably at most 2.0 wt.-%, yet more preferably at most 1 .0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the purge fraction.

92. The process according to any of the preceding claims, wherein the purge fraction has a fructose content of at most 95 wt.-%, preferably at most 90 wt.-%, more preferably at most 85 wt.-%, yet more preferably at most 80 wt.-%, even more preferably at most 75 wt.-%, most preferably at most 70 wt.-%, and in particular at most 65 wt.-%, relative to the dry solids content of the purge fraction.

93. The process according to any of the preceding claims, wherein the purge fraction has a fructose content of at most 5.0 wt.-%, preferably at most 3.5 wt.-%, more preferably at most 2.0 wt.-%, yet more preferably at most 1 .0 wt.-%, even more preferably at most 0.5 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the purge fraction.

94. The process according to any of the preceding claims, wherein the purge fraction has a glucose content of at most 99 wt.-%, preferably at most 95 wt.-%, more preferably at most 90 wt.-%, yetmore preferably at most 85 wt.-%, even more preferably at most 80 wt.-%, most preferably at most 75 wt.-%, and in particular at most 70 wt.-%, relative to the dry solids content of the purge fraction.

95. The process according to any of the preceding claims, wherein the purge fraction has a sucrose content of at most 95 wt.-%, preferably at most 84 wt.-%, more preferably at most 73 wt.-%, yet more preferably at most 62 wt.-%, even more preferably at most 51 wt.-%, most preferably at most 40 wt.-%, and in particular at most 30 wt.-%, relative to the dry solids content of the purge fraction.

96. The process according to any of the preceding claims, wherein the purge fraction, preferably first purge fraction, has a dry solids content of at least 4.0 wt.-%, preferably at least 6.0 wt.-%, more preferably at least 8.0 wt.-%, still more preferably at least 10 wt.-%, yet more preferably at least 12 wt.-%, even more preferably at least 14 wt.-%, most preferably at least 16 wt.-%, and in particular at least 18 wt.-%, relative to the total weight of the purge fraction.

97. The process according to any of the preceding claims, wherein the purge fraction, preferably second purge fraction, has a dry solids content of at least 5.0 wt.-%, preferably at least 10 wt.-%, more preferably at least 15 wt.-%, still more preferably at least 20 wt.-%, yet more preferably at least 25 wt.-%, even more preferably at least 30 wt.-%, most preferably at least 35 wt.-%, and in particular at least 40 wt.-%, relative to the total weight of the purge fraction.

98. The process according to any of the preceding claims, wherein the purge fraction has a content of hydroxymethyl furfural of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

99. The process according to any of the preceding claims, wherein the purge fraction has a content of 2,3-butanedione of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

100. The process according to any of the preceding claims, wherein the purge fraction has a content of acetaldehyde of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably atleast 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

101. The process according to any of the preceding claims, wherein the purge fraction has a content of2-keto-D-glucose of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

102. The process according to any of the preceding claims, wherein the purge fraction has a content of allosone of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

103. The process according to any of the preceding claims, wherein the purge fraction has a content of3 -desoxyglucosone of at least 1 ppmw, preferably at least 5 ppmw, more preferably at least 10 ppmw, yet more preferably at least 25 ppmw, even more preferably at least 50 ppmw, most preferably at least 100 ppmw, and in particular at least 250 ppmw, relative to the dry solids content of the purge fraction.

104. The process according to any of the preceding claims, wherein the one or more concentration and / or purification measures comprise a concentration; preferably reverse osmosis and / or evaporation.

105. The process according to any of the preceding claims, wherein the one or more concentration and / or purification measures comprise a demineralization and / or a decoloration.

106. The process according to any of the preceding claims, wherein the fructose enriched fraction or the concentrated and / or purified fructose enriched fraction is recirculated to step (a).

107. The process according to any of the preceding claims, wherein the fructose enriched fraction or the concentrated and / or purified fructose enriched fraction is recirculated to step (b).

108. The process according to any of the preceding claims, which additionally comprises the steps of(g) concentrating at least one of the one or more allulose enriched fractions thereby obtaining a concentrated allulose enriched fraction;(h) crystallizing allulose from the concentrated allulose enriched fraction thereby obtaining a suspension comprising or essentially consisting of allulose crystals and a liquid phase;(i) separating the allulose crystals and the liquid phase from one another; preferably by centrifugation; and(j) optionally, washing the allulose crystals thereby obtaining washed allulose crystals and a washing water.

109. The process according to claim 108, which additionally comprises the step of(k) recirculating the liquid phase to the crude product or the pre-purified product for subsequent chromatographic separation in step (d).

110. The process according to any of the preceding claims, wherein step (d) comprises the sub-steps(di) chromatographically separating the crude product or the pre-purified product into(a) a first allulose enriched fraction and(P) an intermediate fraction enriched with (i) fructose as well as (ii) one or more impurities and / or glucose and / or sucrose;(d2) chromatographically separating the intermediate fraction into(a) a second allulose enriched fraction;(P) the fructose enriched fraction; and(y) the purge fraction; and(ds) optionally, combining the first allulose enriched fraction and the second allulose enriched fraction with one another; and which additionally comprises the step of(k1) recirculating the liquid phase to the intermediate fraction for subsequent chromatographic separation in sub-step (ds).

111. The process according to any of claims 108 to 110, which additionally comprises the step of(l) recirculating the washing water to the at least one of the one or more allulose enriched fractions for subsequent concentration in step (g).

112. The process according to any of the preceding claims, which comprises the steps of(a) providing a starting composition comprising(a) fructose and(P) optionally, one or more impurities and / or glucose and / or sucrose;(b) contacting the starting composition with an allulose-3 -epimerase to convert fructose into allulose thereby obtaining a crude product comprising(a) allulose,(P) fructose, and(y) one or more impurities and / or glucose and / or sucrose;(c) optionally, subjecting the crude product to one or more pre-purification measures thereby obtaining a pre-purified product comprising(a) allulose,(P) fructose, and(y) one or more impurities and / or glucose and / or sucrose;(d) chromatographically separating the crude product or the pre-purified product into(a) one or more allulose enriched fractions each having independently of one another an allulose content of at least 85 wt.-%, relative to the dry solids content of the allulose enriched fraction; and(P) a fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the fructose enriched fraction; wherein the fructose enriched fraction has a total content of impurities of at most 1.0 wt.-%, preferably at most 0.8 wt.-%, more preferably at most 0.6 wt.-%, yet more preferably at most 0.4 wt.-%, even more preferably at most 0.2 wt.-%, most preferably at most 0.1 wt.-%, and in particular at most 0.01 wt.-%, relative to the dry solids content of the fructose enriched fraction;(e) optionally, subjecting the fructose enriched fraction to one or more concentration and / or purification measures thereby obtaining a concentrated and / or purified fructose enriched fraction having a fructose content of at least 85 wt.-%, relative to the dry solids content of the concentrated and / or purified fructose enriched fraction;(f) recirculating the fructose enriched fraction or the concentrated and / or purified fructose enriched fraction to step (a) or (b); wherein the one or more impurities are any organic compounds other than allulose, fructose, glucose, and sucrose; preferably wherein the one or more impurities comprise(i) allulose dimer, allulose-fructose disaccharide, allulose-glucose disaccharide, allulose tetramer, diallulose anhydride, levulinic acid, y-hydroxy valeric acid (GVA), furfural, hydroxymethyl furfural (HMF), 2,5-dimethylfiirane, 2,5-fiirane dicarboxylic acid (FDCA), 5- hydroxymethyl furane 2-carboxylic acid, 2,5 -formyl furane carboxylic acid, 2,5-fiirane dialdehyde, 2,5-bis-(hydroxy-methyl)fiirane, bis(5-formyl-2-fiirfuryl)ether), fiirane-2-carbox- ylic acid, fiirane-3 -carboxylic acid, 5-hydroxyfiirfiiral, 2,5-dihydro-2,5-dimethoxyfurane, (2R)-5 -oxotetrahydro-2 -furane carboxylic acid, bis(5 -methyl furfiiryljether, 5,5'-methylene- di(furane-2-carboxylic acid), or any combination thereof; and / or(ii) lactic acid, maltol, furaneol, allosone, glucosone (2 -keto-D-glucose), 1 -desoxyglucosone, 3- desoxyglucosone, 3-desoxygalactosone, formic acid, acetic acid, propionic acid, glyoxal, or any combination thereof; and / or(iii) 2,3-butanedione, acetaldehyde, 2-keto-D-glucose (glucosone), 3 -desoxyglucosone, or any combination thereof.

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