Preparation method of psicose

Abstract

The invention belongs to the technical field of functional sugar alcohol production, and particularly relates to a preparation method of psicose. Comprising the following steps: S1, preparing two sets of fructose-MIPs columns, namely an MIPs-1 column and an MIPs-2 column; s2, enabling the raw material solution to pass through a GI column to obtain a fructose-rich solution; s3, enabling the fructose-rich solution to pass through the MIPs-1 column, and returning the effluent to the step S2; s4, enabling the analytical solution of the MIPs-1 column in the step S3 to pass through a DPEase column to obtain a psicose rich solution; and S5, passing the psicose rich solution through an MIPs-2 column, carrying out chromatographic separation on the effluent to obtain a psicose solution and a miscellaneous sugar solution, and returning the desorption solution of the MIPs-2 column to the step S4. According to the method, the fructose is selectively adsorbed through the fructose-MIPs, so that the purity of psicose fed by chromatographic separation is improved to 65% or above, the treatment capacity and the dosage of chromatographic resin are reduced, and the equipment investment can be reduced by 50% or above.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional sugar alcohol production, and in particular relates to a method for preparing psicose. Background Art

[0002] Allulose is a natural ingredient found in fruits and foods such as raisins, figs, kiwis, and brown sugar. It is a white powder, and its aqueous solution is a transparent, colorless liquid that is stable at room temperature and pressure. It is a hexose and ketose, and a rare sugar formed by the phase isomerization of D-fructose at the C-3 position. Its sweetness and taste are similar or nearly similar to those of sucrose, but its calorie count is lower, with only 0.4 kcal per gram. This makes it an ideal sucrose substitute for obese and diabetic patients.

[0003] Currently, psicose is produced by isomerizing fructose through fermentation or enzymatic hydrolysis, followed by chromatographic separation to obtain high-purity psicose. However, fructose itself is a widely used food additive and is relatively expensive. Therefore, there is also a process for producing psicose from glucose. In this process, glucose is converted to fructose using glucose isomerase, and then fructose is converted to psicose using epimerase. However, the conversion rate of the two-step isomerization reaction in this process is not high, at around 30%, necessitating the separation of psicose, glucose, and fructose in the intermediate solution. While separation of psicose from glucose and fructose is relatively easy, separation of glucose from fructose is more difficult, requiring large-scale chromatographic separation equipment and high investment costs. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing psicose to solve the problems existing in the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A method for preparing psicose, comprising the following steps:

[0007] S1. Prepare two sets of fructose-MIPs columns, namely MIPs-1 column and MIPs-2 column;

[0008] S2, passing the raw material liquid through the GI column to obtain a fructose-rich liquid;

[0009] S3, passing the fructose-rich solution through the MIPs-1 column, and returning the effluent to step S2;

[0010] S4, passing the analytical solution from the MIPs-1 column in step S3 through a DPEase column to obtain a psicose-rich solution;

[0011] S5. Pass the psicose-rich solution through the MIPs-2 column, and perform chromatographic separation on the effluent to obtain a psicose solution and a miscellaneous sugar solution. The eluted solution from the MIPs-2 column is returned to step S4.

[0012] S6. Return the mixed sugar solution to step S3.

[0013] Furthermore, the preparation method of the fructose-MIPs column comprises the following steps:

[0014] a. Preassembly: Dissolve fructose and 4-vinylphenylboronic acid (4-VPBA) in borate buffer at pH 8.5, sonicate until completely dissolved, and stir at 25°C for 12 hours.

[0015] b. Polymerization reaction: Add ethylene glycol dimethacrylate (EGDMA), azobisisobutyronitrile (AIBN) and an acetonitrile-toluene mixture, and react in a water bath at 65°C under nitrogen for 24 hours to obtain a polymer;

[0016] c. Crushing: crush the polymer, pass it through 100 mesh and 200 mesh sieves, collect particles between 100-200 mesh, and obtain the sieved material;

[0017] d. Template removal: The sieved material was Soxhlet extracted with a methanol-acetic acid mixture for 48 hours until no fructose remained as determined by HPLC to obtain an extract;

[0018] e. Post-treatment: The extract was washed with pure water until neutral, and vacuum dried at 60°C for 12 hours to obtain fructose-MIPs particles;

[0019] f. Column packing: pack the fructose-MIPs particles into a column to obtain a fructose-MIPs column.

[0020] Furthermore, the fructose-MIPs column analysis method is as follows: after the fructose-MIPs column is emptied, the fructose adsorbed on the fructose-MIPs particles is analyzed with 70°C hot water to obtain an analysis liquid, and then the fructose adsorbed on the fructose-MIPs particles is further analyzed with 0.1wt% acetic acid solution to obtain an acid precipitation liquid, and the acid precipitation liquids of the MIPs-1 column and the MIPs-2 column are collected, passed through an ion exchange resin, and returned to step S4.

[0021] Furthermore, the molar ratio of fructose, 4-VPBA, EGDMA, and AIBN is 1:4:20:0.1, 1 mol of fructose corresponds to 15 L of acetonitrile-toluene mixture, the volume ratio of acetonitrile to toluene in the acetonitrile-toluene mixture is 3:1, and the volume ratio of methanol to acetic acid in the methanol-acetic acid mixture is 9:1.

[0022] Furthermore, in step S2, the GI column is packed with immobilized glucose isomerase.

[0023] Furthermore, in step S2, the raw material liquid is a glucose solution or a solution containing glucose and fructose, and if the raw material liquid is a solution containing glucose and fructose, the raw material liquid is fed starting from step S3.

[0024] Furthermore, in step S4, the DPEase column is packed with immobilized epimerase.

[0025] Furthermore, during the chromatographic separation in step S5, psicose is used as a separation component to obtain a psicose solution, and fructose and glucose are used as other separation components to obtain a mixed sugar solution.

[0026] The present invention has the following beneficial effects:

[0027] 1. Through the selective adsorption of fructose by fructose-MIPs, the purity of allulose in the chromatographic separation feed is increased to more than 65%, thereby reducing the processing volume and amount of chromatographic resin, and equipment investment can be reduced by more than 50%.

[0028] 2. Through the selective adsorption of fructose by fructose-MIPs, the unreacted glucose (effluent) in the glucose isomerase reaction returns to the glucose isomerase (GI column) for reconversion, reducing the fructose inhibition effect. The fructose (analyte) enters the epimerase (DPEase column) to generate allulose, thus forming a closed loop and improving the reaction efficiency.

[0029] 3. Use 70℃ hot water + 0.1% acetic acid to decompose fructose step by step to prevent acetic acid from directly entering the intermediate liquid and affecting production.

[0030] 4. Both glucose and oligofructose by-product liquid can be used to produce allulose, thereby further reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a process flow chart of the present invention using glucose solution as raw material liquid.

[0032] Figure 2 The present invention is a process flow chart of the present invention using a solution containing glucose and fructose as a raw material liquid. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] Example 1:

[0035] like Figure 1 As shown, a method for preparing psicose comprises the following steps:

[0036] A method for preparing psicose, comprising the following steps:

[0037] S1. Prepare two sets of fructose-MIPs columns, namely MIPs-1 column and MIPs-2 column;

[0038] The preparation method of the fructose-MIPs column comprises the following steps:

[0039] a. Preassembly: Dissolve 180 g of fructose and 592 g of 4-VPBA in 2 L of borate buffer (pH 8.5), sonicate until completely dissolved, and stir at 25°C for 12 h.

[0040] b. Polymerization reaction: add 3.96 kg of EGDMA, 16.4 g of AIBN and 15 L of acetonitrile-toluene mixture (acetonitrile 10 L, toluene 5 L), and react in a water bath at 65° C. under nitrogen protection for 24 hours to obtain a polymer;

[0041] c. Crushing: crush the polymer, pass it through 100 mesh and 200 mesh sieves, collect particles between 100-200 mesh, and obtain the sieved material;

[0042] d. Template removal: The sieved material was Soxhlet extracted with a methanol-acetic acid mixture (methanol:acetic acid volume ratio of 9:1) for 48 hours until no fructose remained as determined by HPLC to obtain an extract;

[0043] e. Post-treatment: The extract was washed with pure water until neutral, and vacuum dried at 60°C for 12 hours to obtain fructose-MIPs particles;

[0044] f. Column packing: pack the fructose-MIPs particles into a column to obtain a fructose-MIPs column.

[0045] The fructose-MIPs column decomposition method is as follows: after the fructose-MIPs column is emptied, 70°C hot water is used to decompose the fructose adsorbed on the fructose-MIPs particles to obtain a decomposition solution, and then 0.1wt% acetic acid solution is used to further decompose the fructose adsorbed on the fructose-MIPs particles to obtain an acid precipitation solution. The acid precipitation solutions of the MIPs-1 column and the MIPs-2 column are collected, passed through an ion exchange resin, and returned to step S4.

[0046] The molar ratio of fructose, 4-VPBA, EGDMA, and AIBN is 1:4:20:0.1, 1 mol of fructose corresponds to 15 L of acetonitrile-toluene mixture, the volume ratio of acetonitrile to toluene in the acetonitrile-toluene mixture is 3:1, and the volume ratio of methanol to acetic acid in the methanol-acetic acid mixture is 9:1.

[0047] Fructose is used as the template molecule, 4-VPBA as the functional monomer, EGDMA as the crosslinker, AIBN as the initiator, and an acetonitrile-toluene mixture as the porogen. The prepared fructose-MIPs particles are molecularly imprinted polymers that can specifically recognize and selectively adsorb the template molecule.

[0048] S2. The glucose solution is passed through a GI column to obtain a fructose-rich solution. The GI column is packed with immobilized glucose isomerase. Glucose is converted to fructose through the isomerization reaction of glucose isomerase. The formation of fructose inhibits the isomerization reaction. The maximum fructose conversion rate reaches 27.8%, which means that the fructose purity in the fructose-rich solution is 27.8% and the glucose purity is 72.2%.

[0049] S3: The fructose-rich solution is passed through a MIPs-1 column. The fructose is adsorbed by the MIPs-1 column, and the effluent is mostly glucose. The effluent is returned to step S2 and re-passed through the GI column. Desorption is performed using 70°C hot water. Specifically, the fructose-MIPs particles are soaked in 70°C hot water to dissolve the fructose, resulting in a desorption solution with a fructose purity of 91.1% and a glucose purity of 6.1%, with the remainder being impurities. However, hot water desorption is not as effective as acetic acid desorption, and 10-20% of the fructose remains undesorbed. The fructose adsorbed by the fructose-MIPs particles is further desorbed using a 0.1wt% acetic acid solution to obtain an acid-precipitated solution, which is then collected.

[0050] S4. The elution solution from the MIPs-1 column in step S3 was passed through a DPEase column loaded with immobilized epimerase to obtain a psicose-rich solution. Fructose was isomerized to psicose by the immobilized epimerase. The formation of psicose inhibited the isomerization reaction. The psicose conversion rate was 25.3%. The psicose-rich solution had a fructose purity of 67.5%, a glucose purity of 6%, and a psicose purity of 22.9%, with the remainder being impurities.

[0051] S5. The psicose-rich solution was passed through a MIPs-2 column. The effluent had a fructose purity of 4.1%, a glucose purity of 17.7%, and a psicose purity of 68.6%, with the remainder being impurities. The effluent was subjected to chromatographic separation (decolorization, cross-linking, and concentration were performed to remove impurities before chromatographic separation). During the chromatographic separation, psicose was separated as one component to obtain a psicose liquid, and fructose and glucose were separated as other components to obtain a mixed sugar liquid. The psicose purity in the mixed sugar liquid reached 99.7%, and the fructose purity in the mixed sugar liquid was 14.1%, 61.4%, and 7.2%, with the remainder being impurities. The psicose liquid was further crystallized and purified to obtain solid psicose particles.

[0052] Similarly, the fructose-MIPs particles in the MIPs-2 column were soaked in 70°C hot water to dissolve the fructose, yielding a solution containing 84.9% fructose, 9.5% glucose, and 1.1% psicose, with the remainder being impurities. The solution was returned to step S4 and passed through the DPEase column. The fructose adsorbed by the fructose-MIPs particles was further decomposed using a 0.1 wt% acetic acid solution to yield an acid solution. This solution was combined with the acid solution from step S3, and after multiple cycles to a certain concentration, the solution was desalted using an ion exchange resin and returned to step S4 and passed through the DPEase column.

[0053] S6. Return the mixed sugar solution to step S3 and pass it through the MIPs-1 column. Return the effluent after fructose adsorption to step S2. The analytical solution goes to step S4 and passes it through the DPEase column to recover the mixed sugar solution. This forms a cycle.

[0054] Example 2:

[0055] like Figure 2 As shown, this embodiment provides a method for preparing allulose. The method steps are basically the same as those in Example 1, except that the raw material liquid is a solution containing glucose and fructose, such as a by-product liquid of oligofructose production. The production of oligofructose uses sucrose as a raw material. In the purification step, oligofructose is purified by chromatographic separation. The mixed sugar liquid contains sucrose, glucose, and fructose. After the sucrose is separated again, the remaining solution contains glucose and fructose, which is the by-product liquid of oligofructose.

[0056] The by-product liquid of oligofructose is passed through the MIPs-1 column, and the effluent is returned to step S2 and passed through the GI column to obtain a fructose-rich liquid. The analytical liquid is passed through the DPEase column to obtain a psicose-rich liquid. The remaining steps are the same, thus forming a cycle.

[0057] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should fall within the scope of protection of the present invention.

[0058] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

Claims

1. A method for preparing psicose, characterized in that: The following steps are involved: S1. Prepare two sets of fructose-MIPs columns, namely MIPs-1 column and MIPs-2 column; S2, passing the raw material liquid through the GI column to obtain a fructose-rich liquid; S3, passing the fructose-rich solution through the MIPs-1 column, and returning the effluent to step S2; S4, passing the analytical solution from the MIPs-1 column in step S3 through a DPEase column to obtain a psicose-rich solution; S5. Pass the psicose-rich solution through the MIPs-2 column, and perform chromatographic separation on the effluent to obtain a psicose solution and a miscellaneous sugar solution. The eluted solution from the MIPs-2 column is returned to step S4. S6. Return the mixed sugar solution to step S3.

2. The method for preparing psicose according to claim 1, wherein The preparation method of the fructose-MIPs column comprises the following steps: a. Preassembly: Dissolve fructose and 4-vinylphenylboronic acid (4-VPBA) in borate buffer at pH 8.5, sonicate until completely dissolved, and stir at 25°C for 12 hours. b. Polymerization reaction: Add ethylene glycol dimethacrylate (EGDMA), azobisisobutyronitrile (AIBN) and an acetonitrile-toluene mixture, and react in a water bath at 65°C under nitrogen for 24 hours to obtain a polymer; c. Crushing: crush the polymer, pass it through 100 mesh and 200 mesh sieves, collect particles between 100-200 mesh, and obtain the sieved material; d. Template removal: The sieved material was Soxhlet extracted with a methanol-acetic acid mixture for 48 hours until no fructose remained as determined by HPLC to obtain an extract; e. Post-treatment: The extract was washed with pure water until neutral, and vacuum dried at 60°C for 12 hours to obtain fructose-MIPs particles; f. Column packing: pack the fructose-MIPs particles into a column to obtain a fructose-MIPs column.

3. The method for preparing psicose according to claim 2, wherein: The fructose-MIPs column decomposition method is as follows: after the fructose-MIPs column is emptied, 70°C hot water is used to decompose the fructose adsorbed by the fructose-MIPs particles to obtain a decomposition solution, and then 0.1wt% acetic acid solution is used to further decompose the fructose adsorbed by the fructose-MIPs particles to obtain an acid decomposition solution. The acid decomposition solutions of the MIPs-1 column and the MIPs-2 column are collected, passed through an ion exchange resin, and returned to step S4.

4. The method for preparing psicose according to claim 2, wherein: The molar ratio of fructose, 4-VPBA, EGDMA, and AIBN is 1:4:20:0.1, 1 mol of fructose corresponds to 15 L of acetonitrile-toluene mixture, the volume ratio of acetonitrile to toluene in the acetonitrile-toluene mixture is 3:1, and the volume ratio of methanol to acetic acid in the methanol-acetic acid mixture is 9:

1.

5. The method for preparing psicose according to claim 1, wherein The GI column in step S2 is packed with immobilized glucose isomerase.

6. The method for preparing psicose according to claim 1, wherein: The raw material liquid in step S2 is a glucose solution or a solution containing glucose and fructose, and if the raw material liquid is a solution containing glucose and fructose, the raw material liquid is fed starting from step S3.

7. The method for preparing psicose according to claim 1, wherein: The DPEase column in step S4 is formed by packing the immobilized epimerase.

8. The method for preparing psicose according to claim 1, wherein: During the chromatographic separation in step S5, psicose is used as a separation component to obtain a psicose solution, and fructose and glucose are used as other separation components to obtain a mixed sugar solution.

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