A method for refining D-psicose

Abstract

The present invention discloses a method for refining D-psicose, relating to the technical field of D-psicose production. When dissolving crude D-psicose, ethanol is used instead of water. Because D-psicose has a high solubility in water and is difficult to crystallize, it must first be concentrated to a concentration greater than 80%, and then cooled or ethanol is added to obtain crystals. This is time-consuming and cumbersome to operate. The present invention directly uses ethanol to heat and dissolve the crude D-psicose, eliminating the process of concentrating and evaporating water. Crystals can be obtained by directly controlling the cooling, saving equipment and energy consumption. At the same time, the present invention adopts a cooling crystallization method, so that crystals can be precipitated during the cooling process. A small amount of seed crystals is added before the system precipitates crystals, so that larger crystals can be quickly obtained, and the operation is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of D-psicose production, and in particular to a method for refining D-psicose. Background Art

[0002] D-psicose, a hexose and ketose, is a rare and important sugar formed by the isomerization of D-fructose at the C3 position. It is found primarily in wheat, schizophyllum, beet molasses, and sugarcane molasses. Furthermore, because fructose can be converted to D-psicose through a non-enzymatic isomerization reaction when heated, some sugary, heat-treated foods, such as baked goods, sauces, brewed coffee, and fruit juices subjected to prolonged high-temperature treatment, also contain a certain amount of D-psicose. D-psicose has a sweetness equivalent to 70% of that of an equivalent amount of sucrose, but only 0.3% of its calories. It also has similar taste and bulk properties to sucrose. Unlike glucose, allulose undergoes almost no metabolism and produces no energy after intestinal absorption in the human body. It is also rarely fermented and utilized by intestinal microorganisms, effectively reducing energy intake and possessing physiological functions such as regulating blood sugar, lowering lipids and reducing weight, and preventing and treating type 2 diabetes and its complications. This characteristic of D-allulose is also its most prominent advantage as an alternative sweetener. Furthermore, D-allulose can undergo a Maillard reaction with proteins or amino acids. Compared to other D-ketoses (such as D-tagatose, sorbitol, and fructose), its reaction product exhibits outstanding gelling properties, foaming ability, emulsification stability, and good antioxidant properties, which can improve the texture, flavor, and taste of food.

[0003] Currently, the method for obtaining D-psicose crystals mainly involves concentrating a purified aqueous solution of psicose to a concentration of >80%, then directly obtaining the product through a series of steps such as cooling, adding ethanol, and adding seed crystals. Without refined crystallization, the product is often accompanied by some impurities, which have a certain impact on the product. The crystals will turn yellow in color within a very short shelf life, and the resulting product is mostly powdery.

[0004] Commercially available D-psicose products are mostly liquid and powdered solids. However, as a low-calorie sweetener, powdered solids tend to clump together when added in large quantities, making them difficult to dissolve quickly, limiting the product's application. Large D-psicose crystals can effectively avoid this problem, and large crystals also facilitate separation from the mother liquor. Prior art methods mention that large-grain D-psicose crystals can be obtained through evaporative crystallization, but this requires a very high vacuum and harsh process conditions. Cooling crystallization also requires evaporative crystallization to obtain large crystals, and the crystals are smaller overall than those obtained through evaporative crystallization, resulting in a low yield. Furthermore, the crystallization process requires an ultrasonic step during the cooling crystallization process. Although this improves the crystal size, the process suffers from poor operability and high equipment costs in actual production, making large-scale production difficult. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to address the deficiencies in the existing technology and provide a method for refining D-psicose, wherein the prepared D-psicose has large crystals, good stability and high product quality.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A method for refining D-psicose comprises the following steps:

[0008] A: Add crude D-psicose to ethanol at 50-70°C and stir until fully dissolved to obtain a mixed solution.

[0009] B: Add activated carbon to the mixed solution for decolorization, control the decolorization temperature at 50-70°C, perform hot filtration to remove the activated carbon after decolorization, and collect the decolorized liquid;

[0010] C: Maintaining a stirring speed of 30-80 rpm, the decolorizing solution was cooled to 40-50°C while stirring, and then D-psicose seed crystals were added. The temperature was lowered to -5-5°C, and the solution was filtered through a 10-15 μm sand core funnel to obtain the wet D-psicose product.

[0011] D: The wet D-psicose product in step C is vacuum dried to obtain the finished D-psicose product.

[0012] Preferably, the volume of ethanol added in step A accounts for 80-150% (ml / g) of the weight of the crude D-psicose.

[0013] Preferably, the amount of activated carbon added in step B is 0.5-5% of the weight of the crude D-psicose in step A.

[0014] Preferably, the decolorization time in step B is 10 to 50 minutes.

[0015] In step C, the amount of D-psicose seed crystals added is 0.1-1% by weight of the crude D-psicose product.

[0016] The size of the D-psicose seed crystals added in step C is 60-100 mesh.

[0017] The cooling rate after adding the D-psicose seed crystals in step C is 1-5°C / h.

[0018] The filtrate after filtration through the sand core funnel in step C enters an evaporator, where the temperature is controlled at 40-70°C and the vacuum degree is ≤-0.09 MPa. The ethanol evaporated is at a temperature of 15-20°C and then heated to 50-70°C to be used again to dissolve the crude D-psicose. The remaining kettle residue is combined with the mixed solution in step A for subsequent decolorization and crystallization.

[0019] The drying temperature in step D is 40-50° C., and the vacuum degree is ≤-0.09 MPa.

[0020] The purity of the D-psicose product obtained in step D is ≥99.0%, the refining yield is ≥90%, and more than 80% of the crystal particle size is 30-50 mesh.

[0021] The synthesis process of crude D-psicose is as follows: fructose is used as a substrate, fructose isomerase is added, and a conversion liquid containing D-psicose is obtained after conversion. The conversion liquid is filtered, subjected to a positive column, a negative column, and chromatographic purification to obtain a D-psicose purified liquid. The purified liquid is concentrated, crystallized, and filtered to obtain crude D-psicose.

[0022] The method for synthesizing crude D-psicose is not limited to the above method and may be any other method for synthesizing crude D-psicose in the prior art.

[0023] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1. The present invention uses ethanol rather than water to dissolve crude D-psicose. This is because D-psicose has a high solubility in water and is difficult to crystallize. It must first be concentrated to a concentration greater than 80%, and then cooled or ethanol added to obtain crystals. This is time-consuming and cumbersome. The present invention directly uses ethanol to dissolve the crude D-psicose by heating, eliminating the process of concentrating and evaporating water. Crystals can be obtained by directly controlling the cooling, saving equipment and energy consumption.

[0025] 2. The present invention adopts the cooling crystallization method, which can precipitate crystals during the cooling process. A small amount of seed crystals is added before the system precipitates crystals, which can quickly obtain larger-sized crystals and is simple to operate.

[0026] 3. More than 80% of the D-psicose crystals obtained by the method of the present invention have a particle size of 30-50 mesh, large crystal particles, and good stability.

[0027] 4. The D-psicose product obtained by the method of the present invention has a high purity of above 99.8%, and the D-psicose is of high quality.

[0028] 5. The yield of D-psicose obtained by the method of the present invention is above 92%, the product yield is high, the raw material utilization rate is good, and waste is reduced.

[0029] 6. The method of the present invention does not generate hazardous waste, and the filtrate after crystallization can be recycled to avoid waste and damage to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a crystal form image of the finished product of D-psicose in Example 1 of the present invention under a 10x microscope;

[0031] Figure 2 is a liquid chromatogram of the finished D-psicose product in Example 1 of the present invention;

[0032] Figure 3 This is a crystal form image of the finished product of D-psicose in Example 2 of the present invention under a 10x microscope;

[0033] Figure 4 is a liquid chromatogram of the finished D-psicose product in Example 2 of the present invention;

[0034] Figure 5 This is a crystal form image of the finished product of D-psicose in Example 3 of the present invention under a 10x microscope;

[0035] Figure 6 This is a liquid chromatogram of the finished D-psicose in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the embodiments.

[0037] Example 1

[0038] 1. Dissolve 2 kg of crude D-psicose in 1.6 L of 95% ethanol at 70°C and stir thoroughly to obtain a mixed solution.

[0039] 2. Add 100 g of activated carbon to the mixed solution, control the decolorization temperature at 70°C, decolorize for 10 minutes, filter hot, and collect the decolorized liquid.

[0040] 3. The decolorizing solution was stirred and cooled to 40°C. 2 g of 100-mesh D-psicose seed crystals were added to the decolorizing solution at 30 rpm. The decolorizing solution was then cooled to 5°C at a rate of 1°C / h. The wet D-psicose product was filtered through a 10-15 μm sand core funnel.

[0041] 4. The wet D-psicose was dried at 40°C and vacuum degree -0.09 MPa to obtain 1.84 kg of D-psicose finished product. The D-psicose finished product was white granular crystals. Figure 1 As shown in FIG, the purity of the D-psicose product was 99.9%, and the refined yield was 92.0%. The liquid chromatogram was as shown in FIG. Figure 2 shown.

[0042] 5. The filtrate (volume 1.7 L) after filtration through the sand core funnel in step 3 was fed into an evaporator, controlled at 70°C and under a vacuum of -0.09 MPa. The distilled ethanol (volume 1.5 L) was heated to 70°C under normal pressure and then used again to dissolve the crude D-psicose. The remaining kettle residue (volume 0.2 L) was combined with the mixed solution in step 1 for subsequent decolorization and crystallization.

[0043] Example 2

[0044] 1. Dissolve 2 kg of crude D-psicose in 2.4 L of 95% ethanol at 60°C and stir thoroughly to obtain a mixed solution.

[0045] 2. Add 50 g of activated carbon to the mixed solution, control the decolorization temperature at 60°C, decolorize for 30 minutes, filter hot, and collect the decolorized liquid.

[0046] 3. Stir and cool the decolorizing solution to 45°C at 50 rpm, add 10 g of 80-mesh D-psicose seed crystals, and cool to 0°C at a rate of 3°C / h. Filter through a 10-15 μm sand core funnel to obtain the wet D-psicose product.

[0047] 4. The wet D-psicose product was dried at 45°C and vacuum degree -0.09 MPa to obtain 1.88 kg of D-psicose finished product. The D-psicose finished product was white granular crystals. Figure 3 As shown, the purity of the finished D-psicose was 99.8%, and the refined yield was 94.0%. The liquid chromatogram was as shown in FIG. Figure 4 shown.

[0048] 5. The filtrate (2.5 L) after filtration through the sand core funnel in step 3 was fed into an evaporator, and the temperature was controlled at 60°C under a vacuum of -0.09 MPa. The distilled ethanol (2.3 L) was heated to 60°C under normal pressure and then used again to dissolve the crude D-psicose. The remaining kettle residue (0.2 L) was combined with the mixed solution in step 1 for subsequent decolorization and crystallization.

[0049] Example 3

[0050] 1. Dissolve 2 kg of crude D-psicose in 3.0 L of 95% ethanol at 50°C and stir thoroughly to obtain a mixed solution.

[0051] 2. Add 10 g of activated carbon to the mixed solution, control the decolorization temperature to 50°C, decolorize for 50 minutes, filter hot, and collect the decolorized liquid.

[0052] 3. The decolorizing solution was stirred and cooled to 50°C. 20 g of D-psicose seed crystals (60 mesh) were added to the decolorizing solution at 80 rpm. The decolorizing solution was then cooled to -5°C at a rate of 5°C / h. The wet D-psicose product was filtered through a 10-15 μm frit funnel.

[0053] 4. The wet D-psicose was dried at 50°C and vacuum degree -0.09 MPa to obtain 1.85 kg of D-psicose finished product. The D-psicose finished product was white granular crystals. Figure 5 As shown, the purity of the finished D-psicose was 99.8%, and the refined yield was 92.5%. The liquid chromatogram was as shown in FIG. Figure 6 shown.

[0054] 5. The filtrate (3.1 L) after filtration through the sand core funnel in step 3 was fed into an evaporator, and the temperature was controlled at 50°C and the vacuum degree was -0.09 MPa. The distilled ethanol (2.9 L) was heated to 50°C under normal pressure and then used again to dissolve the crude D-psicose. The remaining kettle residue (0.2 L) was combined with the mixed solution in step 1 for subsequent decolorization and crystallization.

[0055] It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the application.

Claims

1. A method for refining D-psicose, characterized in that The following steps are involved: A: Add crude D-psicose to ethanol at 50-70°C and stir until fully dissolved to obtain a mixed solution. B: Add activated carbon to the mixed solution for decolorization, control the decolorization temperature at 50-70°C, perform hot filtration to remove the activated carbon after decolorization, and collect the decolorized liquid; C: Maintaining a stirring speed of 30-80 rpm, the decolorizing solution was cooled to 40-50°C while stirring, and then D-psicose seed crystals were added. The temperature was then lowered to -5-5°C at a rate of 1-5°C / h. The wet D-psicose product was filtered through a 10-15 μm sand core funnel. D: The wet D-psicose product in step C is vacuum dried to obtain a finished D-psicose product with a purity of ≥99.0%, a yield of ≥90%, and a crystal particle size of more than 80% of 30-50 mesh.

2. The method for refining D-psicose according to claim 1, wherein: The volume of ethanol added in step A accounts for 80 to 150% ml / g of the weight of the crude D-psicose.

3. The method for refining D-psicose according to claim 1, wherein: The amount of activated carbon added in step B is 0.5-5% of the weight of the crude D-psicose in step A.

4. The method for refining D-psicose according to claim 1, wherein: The decolorization time in step B is 10 to 50 minutes.

5. The method for refining D-psicose according to claim 1, wherein: In step C, the amount of D-psicose seed crystals added is 0.1-1% by weight of the crude D-psicose product.

6. The method for refining D-psicose according to claim 1, wherein: The size of the D-psicose seed crystals added in step C is 60-100 mesh.

7. The method for refining D-psicose according to claim 1, wherein: The filtrate after filtration through the sand core funnel in step C enters an evaporator, where the temperature is controlled at 40-70°C and the vacuum degree is ≤-0.09 MPa. The distilled ethanol is heated to 50-70°C and then used again to dissolve the crude D-psicose. The remaining kettle residue is combined with the mixed solution in step A for subsequent decolorization and crystallization.

8. The method for refining D-psicose according to claim 1, wherein: The drying temperature in step D is 40-50° C., and the vacuum degree is ≤-0.09 MPa.

Images