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EP-4257595-B1 - METHOD FOR PREPARING CRYSTALLINE D-PSICOSE

EP4257595B1EP 4257595 B1EP4257595 B1EP 4257595B1EP-4257595-B1

Inventors

  • DU, QIAN
  • LI, Fanghua
  • GAN, Zhaobo
  • SHAO, Xianbao
  • ZHANG, Xingjing
  • LIU, SHUANGSHUANG

Dates

Publication Date
20260506
Application Date
20211203

Claims (7)

  1. A preparation method of crystalline D-psicose, characterized in that the method comprises: 1) adding D-psicose crystal seeds when a solid mass content of a D-psicose syrup is 70~75% to perform an evaporative crystallization; 2) performing a crystal regulation on the product of step 1), said crystal regulation is carried out by adding water at the same time as an evaporative crystallization is performed, and a solid mass content of the D-psicose syrup is maintained in a range of 80% to 85% during the crystal regulation process; 3) performing a cooling crystallization on the product of step 2), said cooling crystallization is performed by applying a stepped cooling, wherein said stepped cooling has following operations: in a range of 50~41°C, cooling at a rate of 0.1~0.3°C per hour; in a range of 41~35°C, cooling at a rate of 0.4~0.6°C per hour; in a range of 35~30°C, cooling at a rate of 0.9~1.1°C per hour; and the crystallization is finished when temperature is cooled to 30°C.
  2. The preparation method according to claim 1, characterized in that it specifically comprises the following steps: (1) providing a D-psicose syrup, in which said D-psicose syrup has a solid mass content of 70~75%, adding D-psicose crystal seeds, performing evaporative crystallization at 40~50°C, until the D-psicose syrup has a solid mass content of 80~85%; (2) crystal regulation: supplementing water to the D-psicose syrup obtained in step (1), and at the same time continuously performing an evaporative crystallization, consistently maintaining a solid mass content of the D-psicose syrup in a range of 80~85%, wherein the crystal regulation is performed for 4~8h; (3) cooling crystallization: the D-psicose syrup obtained in step (2) after the completion of the crystal regulation is subjected to stepped cooling crystallization, in which in a range of 50~41°C, cooling at a rate of 0.1~0.3°C per hour; in a range of 41~35°C, cooling at a rate of 0.4~0.6°C per hour; in a range of 35~30°C, cooling at a rate of 0.9~1.1°C per hour; and the crystallization is finished when temperature is cooled to 30°C, then performing centrifugation, washing and drying to obtain crystalline D-psicose.
  3. The preparation method according to claim 2, characterized in that , said D-psicose syrup in step (1) has a solid mass content of 73~75%, and a purity of ≥95%.
  4. The preparation method according to claim 2, characterized in that , said D-psicose crystal seeds in step (1) is added in an amount of 1~1.5‰ with respect to the mass of the D-psicose syrup having a solid mass content of 70~75%.
  5. The preparation method according to claim 2, characterized in that , said D-psicose crystal seeds in step (1) have sizes in a range of 250~280 mesh.
  6. The preparation method according to claim 2, characterized in that , said evaporative crystallization in step (1) is performed at a vacuum degree of -0.05~-0.1 MPa.
  7. The preparation method according to claim 2, characterized in that , in said cooling crystallization process in step (3), a stirring with a speed of 100~150 rpm is applied.

Description

Technical Field The application relates to a method for preparing crystalline D-psicose, belonging to the technical field of functional sugar preparation. Background Art D-psicose or D-allulose is a six-carbon sugar found in very low levels in the nature and is a differential isomer of the C-3 site of D-fructose. D-psicose is difficult to digest and absorb and provides little energy for vital activities, making it a very useful low-calorie sweetener. In the field of medicine and health, D-psicose inhibits hepatic lipogenic enzyme and intestinal α-glucosidase, thereby reducing the accumulation of body fat and suppressing the rise in blood glucose concentration. Dietary addition of D-psicose reduces the postprandial glycaemic response and improves insulin sensitivity and glucose tolerance. In addition, D-psicose is more effective in scavenging reactive oxygen radicals compared to other rare sugars. In mouse tests, D-psicose is found to prevent testicular damage induced by bis-(2-ethylhexyl)-phthalic acid by inhibiting the production of reactive oxygen species. In addition, D-psicose has a neuroprotective effect against 6-hydroxydopamine-induced apoptosis and also inhibits the expression of the monocyte chemotactic protein MCP-1 induced by high glucose concentrations. This predicts a potential function of D-psicose in the treatment of diseases related to diseases such as neurodegeneration and atherosclerosis, etc. Chinese patent document CN109748940A (application number 201811470319.5) discloses a method for crystallization of D-psicose from an ethanol solution, which comprises: a purified D-psicose solution is taken and concentrated under reduced pressure to obtain solution I; the concentrated solution I is heated, added with absolute ethanol, concentrated again under reduced pressure to allow the ethanol take away water in the D-psicose solution to obtain an ethanol solution II of D-psicose; the concentrated solution II is added with absolute ethanol, heated until the D-psicose is completely dissolved, then slowly cooled, continuously cooled slowly when the crystal appears, cooled until crystal no longer increases to obtain a mixed solution III; the mixed solution III is solid-liquid separated to obtain a solid IV and a clear liquid V; the solid IV is dried under a reduced pressure to obtain crystalline D-psicose; the clear liquid V is continuously concentrated, and the above steps are repeated to obtain remaining crystalline D-psicose by crystallization. Contents of the Invention The inventors found that the size distribution of crystalline D-psicose obtained by the existing D-psicose crystallization technology is relatively wide. In view of the deficiencies in the prior art, the present application provides a method for preparing crystalline D-psicose, the size distribution of the crystals of the prepared crystalline D-psicose is narrow, wherein more than 80% of the crystals have sizes in a range of 40 to 60 mesh. The inventors of the present application studied the properties of D-psicose in metastable zone by plotting D-psicose metastable zone curves. In view of the unique metastable zone curves of D-psicose, the present application adopts specific cooling intervals with specific cooling rates during the cooling crystallization process. Based on this, the crystalline D-psicose prepared by the method of the present application has a narrow size distribution. The technical solutions of this application are as follows: In some embodiments, the present application provides a method for preparing crystalline D-psicose, which comprises: (1) evaporative crystallization, (2) crystal regulation, and (3) cooling crystallization, to prepare crystalline D-psicose. In some embodiments, the present application provides a method for preparing crystalline D-psicose, comprising: (1) performing evaporative crystallization on a D-psicose syrup;(2) performing crystal regulation (crystallization regulation) on the product of the previous step;(3) performing cooling crystallization on the product of the previous step to obtain crystalline D-psicose. In some embodiments, the evaporative crystallization comprises adding crystal seeds to a D-psicose syrup having a solid mass content of 70~75% (e.g., 70%~71%, 71%~72%, 72%~73%, 73%~74% or 74%~75%) to perform evaporative crystallization. In some embodiments, the crystal regulation carried out by adding water at the same time as an evaporative crystallization is performed, and a solid mass content is maintained constant during the crystal regulation process. For example, a solid mass content is maintained in a range of 80% to 85%. In some embodiments, the cooling crystallization adopts a stepped cooling method for crystallization in which a slow cooling is applied in an initial stage and a rapid cooling rate is applied in a later stage. In some embodiments, the cooling crystallization is performed by applying a stepped cooling method for crystallization, in which a slow cooling is a