A kind of preparation method of polyglycerol ester

Abstract

The present invention provides a method for preparing polyglycerol ester, and relates to the technical field of chemical synthesis. The method for preparing polyglycerol ester comprises the following steps: (1) taking glycerol, adjusting the pH value to 3-4, adding a composite catalyst, polymerizing, and obtaining polyglycerol; (2) in a bubbling reactor system, fatty acid and the polyglycerol obtained in step (1) are synthesized into polyglycerol ester under the catalysis of immobilized lipase; wherein the composite catalyst in step (1) is composed of cutinase and lipase. The present invention finally obtains the preparation of polyglycerol by using cutinase and lipase as composite catalysts through the selection of catalysts, and polyglycerol is synthesized into polyglycerol ester with fatty acid under the catalysis of immobilized lipase, and the conditions are mild and easy to control, the product color is significantly improved, there is no peculiar smell, there are relatively few impurities, the structure is reasonable, the performance is excellent, and it is environmentally friendly without the discharge of three wastes.

Description

Technical Field

[0001] The invention relates to a method for preparing highly hydrophilic polyglycerol ester simply and at low cost, and belongs to the field of chemical synthesis. Background Art

[0002] Polyglycerol fatty acid ester (abbreviated as polyglycerol ester, PGFE) is an ester formed by polyglycerol and fatty acid. As a new type of emulsifier, it is widely used in food, daily chemicals, medicine and other fields because of its many advantages such as naturalness, high safety, wide HLB value range and good emulsification stability.

[0003] Chinese invention patent CN106084209B discloses a production process for polyglycerol fatty acid esters, which synthesizes high-quality polyglycerol fatty acid esters by rationally selecting catalysts and a two-stage method. The reaction conditions of this method are mild and easy to control, and the product color is significantly improved, has no odor, has relatively few impurities, has a reasonable structure, has excellent performance, is environmentally friendly, and does not discharge three wastes.

[0004] Chinese invention patent application CN109628232A discloses a method for preparing polyglycerol fatty acid ester. The preparation method comprises the following steps: firstly, glycerol is polymerized under the catalysis of KF-SnCl2 / Al2O3 supported solid base catalyst to obtain mixed polyglycerol, then the mixed polyglycerol is purified by molecular distillation to obtain relatively pure polyglycerol, and then the purified polyglycerol is esterified with liquid fatty acid to obtain polyglycerol fatty acid ester. The polyglycerol obtained by the preparation method has a concentrated degree of polymerization and is mainly a straight chain structure. The produced polyglycerol fatty acid ester not only tastes good, has a light smell and a light color, but also can reach the same level as imported products and meets the national food additive safety standards.

[0005] The study found that the technical problem with polyglycerol fatty acid esters and their preparation processes in the prior art is that they are mainly prepared by an intermittent method, which results in problems such as dark color, odor, low emulsifying power, more impurities and high production costs, which limits their application in food and cosmetics. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for preparing polyglycerol esters. By selecting a catalyst, cutinase and lipase are used as a composite catalyst to prepare polyglycerol. Polyglycerol is synthesized into polyglycerol esters with fatty acids under the catalysis of immobilized lipase. The conditions are mild and easy to control. The product color is significantly improved, there is no peculiar smell, impurities are relatively small, the structure is reasonable, the performance is excellent, and it is environmentally friendly without the discharge of three wastes.

[0007] The present invention is achieved through the following technical solutions:

[0008] The first aspect of the present invention is to provide a method for preparing a polyglycerol ester, comprising the steps of:

[0009] (1) Take glycerol, adjust the pH value to 3-4, add a composite catalyst, polymerize, and obtain polyglycerol;

[0010] (2) in a bubbling reactor system, the fatty acid and the polyglycerol obtained in step (1) are reacted to synthesize polyglycerol ester under the catalysis of immobilized lipase;

[0011] Wherein, the composite catalyst in step (1) is composed of cutinase and lipase; and the immobilized lipase in step (2) is to fix the lipase on silica gel to form a silica gel-loaded lipase system.

[0012] Preferably, the mass fraction of the immobilized lipase in the silica gel-loaded lipase system in step (2) is 30-50%.

[0013] Preferably, the mass ratio of cutinase to lipase in the composite catalyst is 1:1-3.

[0014] Preferably, in step (1), the mass ratio of glycerol to the composite catalyst is 90-100:1-2.

[0015] Preferably, in step (1), the polymerization time is 2-6 hours and the polymerization temperature is 20-40°C.

[0016] Preferably, the air flow rate of the bubbling reactor in step (2) is 4-7 L / min.

[0017] Preferably, in step (2), the mass ratio of the immobilized lipase to the substrate (ie, fatty acid to polyglycerol) is 15-25:1000.

[0018] Preferably, the fatty acid in step (2) is one or a mixture of capric acid, lauric acid, myristic acid, oleic acid and stearic acid.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The method of the present invention obtains polyglycerol by polymerizing glycerol using a composite enzyme catalyst. The process conditions are mild and avoids the use of strong alkali or strong acid as a catalyst, which results in the product obtained after the glycerol polymerization being dark in color and having an odor; (2) During the production process of the method of the present invention, there are few impurities and high purity; (3) The polyglycerol fatty acid ester prepared by the present invention is of high quality and can be used not only in the fields of food, medicine, and cosmetics, but also in the fields of textiles, coatings, plastics, pesticides, and rubber, and has great market potential. DETAILED DESCRIPTION

[0020] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary description of the scope of the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of the present invention.

[0021] In the following examples and comparative examples, cutinase was purchased from Beijing Inokai Technology Co., Ltd. with a product number of Novozymes 51032; lipase was purchased from Sigma-Aldrich with a product number of SAE0065.

[0022] Embodiment 1:

[0023] A method for preparing polyglycerol ester comprises the following steps:

[0024] (1) Take 92 g of glycerol, adjust the pH value to 3, add 2 g of composite catalyst (including 0.5 g of cutinase and 1.5 g of lipase), polymerize for 2 h at a polymerization temperature of 30 ° C to obtain polyglycerol;

[0025] (2) In a bubbling reactor system, 1136 g of stearic acid and the polyglycerol obtained in step (1) are catalyzed by 12 g of immobilized lipase (6 g of lipase is immobilized on 6 g of silica gel) to synthesize polyglycerol ester, which is filtered through a filter press and then sprayed with powder.

[0026] Embodiment 2:

[0027] A method for preparing polyglycerol ester comprises the following steps:

[0028] (1) Take 92g of glycerol, adjust the pH value to 3, add 2g of composite catalyst (including 1g of cutinase and 1g of lipase), polymerize for 2h at a polymerization temperature of 30°C to obtain polyglycerol;

[0029] (2) In a bubbling reactor system, 1136 g of stearic acid and the polyglycerol obtained in step (1) are catalyzed by 12 g of immobilized lipase (6 g of lipase is immobilized on 6 g of silica gel) to synthesize polyglycerol ester, which is filtered through a filter press and then sprayed with powder.

[0030] Embodiment 3:

[0031] A method for preparing polyglycerol ester comprises the following steps:

[0032] (1) Take 100 g of glycerol, adjust the pH value to 3, add 1 g of composite catalyst (including 0.5 g of cutinase and 0.5 g of lipase), polymerize for 2 h at a polymerization temperature of 30 ° C to obtain polyglycerol;

[0033] (2) In a bubbling reactor system, 1136 g of stearic acid and the polyglycerol obtained in step (1) were catalyzed by 12 g of immobilized lipase (3.6 g of lipase was immobilized on 8.4 g of silica gel) to synthesize polyglycerol ester, which was filtered through a filter press and then sprayed with powder.

[0034] Comparative Example 1:

[0035] A method for preparing polyglycerol ester comprises the following steps:

[0036] (1) Take 92 g of glycerol, adjust the pH value to 3, add 2 g of lipase, polymerize for 2 h at a polymerization temperature of 30 °C, and obtain polyglycerol;

[0037] (2) In a bubbling reactor system, 1136 g of stearic acid and the polyglycerol obtained in step (1) are catalyzed by 12 g of immobilized lipase (6 g of lipase is immobilized on 6 g of silica gel) to synthesize polyglycerol ester, which is filtered through a filter press and then sprayed with powder.

[0038] Comparative Example 2:

[0039] A method for preparing polyglycerol ester comprises the following steps:

[0040] (1) Take 92 g of glycerol, adjust the pH value to 3, add 2 g of composite catalyst (including 0.5 g of cutinase and 1.5 g of lipase), polymerize for 2 h at a polymerization temperature of 30 ° C to obtain polyglycerol;

[0041] (2) In a bubbling reactor system, 1136 g of stearic acid and the polyglycerol obtained in step (1) are catalyzed by 6 g of lipase to synthesize polyglycerol ester, which is filtered through a filter press and then sprayed with powder.

[0042] Comparative Example 3:

[0043] According to Example 2 in Chinese invention patent CN113912835B, specifically:

[0044] The present embodiment provides a preparation process of polyglycerol fatty acid ester, comprising the following steps:

[0045] Continuous glycerol polymerization and dehydration: 10 kg of glycerol and 72 g of potassium carbonate are measured and mixed by an electronic scale, a certain amount of glycerol is pumped into the No. 1 polymerization kettle 1 by a vacuum pump 5, potassium carbonate is added after stirring is turned on, a trace amount of high-purity nitrogen is introduced and the temperature is raised and stirred, the polymerization temperature of the No. 1 polymerization kettle 1 is controlled to be 232°C, the polymerization temperature of the No. 2 polymerization kettle 2 is controlled to be 250°C, the polymerization temperature of the No. 3 polymerization kettle 3 is controlled to be 252°C, and the polymerization temperature of the No. 4 polymerization kettle 4 is controlled to be 255°C, the vacuum pressure is -0.1 MPa, and the continuous high-purity nitrogen is used to bring out the water produced by the polymerization, and the water is collected by a storage tank 6 with a weighing function to obtain polyglycerol by reaction.

[0046] The polymerization reaction time is 11.6 hours, and when the water storage reaches 12% of the weight of glycerol, the polymerization reaction is stopped to obtain polyglycerol. The pressure of high-purity nitrogen shall not exceed 0.1 MPa.

[0047] Ester exchange: 24 kg of stearic acid and polyglycerol were used as raw materials to carry out ester exchange reaction in esterification kettle No. 1 7 and esterification kettle No. 2 10, and 16.8 g of potassium carbonate was added to catalyze the reaction. The vacuum pressure of the reaction was -0.1 MPa, the reaction temperature in esterification kettle No. 1 7 was 178°C, and the reaction temperature in esterification kettle No. 2 10 was 198°C. The reaction time was 3.8 hours, and nitrogen protection was used. After the reaction, the temperature was lowered to obtain the crude polyglycerol fatty acid ester. Specifically, the ester exchange reaction is carried out under vacuum, the alkali catalyst is passed through the gear pump 19 through the mass flow meter 8 into the No. 1 esterification kettle 7, the heat transfer oil is heated and mechanically stirred, the temperature is raised to 178°C, nitrogen is filled, and when the liquid level of the No. 1 esterification kettle 7 reaches the discharge position, the No. 1 discharge pump 9 is turned on, and the No. 1 discharge pump 9 automatically controls the speed through the liquid level, and the materials in the No. 1 esterification kettle 7 are passed into the No. 2 esterification kettle 10, and the heating and stirring are continued to react, and the temperature is raised to 198°C, and a trace amount of high-purity nitrogen is filled, and the nitrogen pressure shall not exceed 0.1MPa, and the water generated by the reaction is continuously taken out, and the reaction is terminated when the water volume reaches 0.34% of the weight of stearic acid. When the liquid level of the No. 2 esterification kettle 10 reaches the discharge position, the No. 2 discharge pump 13 is turned on, and the No. 2 discharge pump 13 automatically controls the speed through the liquid level.

[0048] Cooling and standing: The coarse material of polyglycerol fatty acid ester is cooled by the cooler 14 and enters the No. 1 standing kettle 15. When the overflow level is reached, it enters the No. 2 standing kettle 16. When the No. 2 standing kettle 16 reaches the overflow level, it enters the finished product kettle 17. Among them, the No. 1 standing kettle 15 and the No. 2 standing kettle 16 are protected by nitrogen, the concentration of nitrogen is ≥99.9%, and the pressure is ≤0.3MPa; circulating cooling water is introduced into the finished product kettle 17 to cool the material to 92°C.

[0049] Powder spraying and sieving: the material is passed into the powder spraying tower 18, the feed temperature is controlled at 92°C, and the powder fineness after powder spraying and sieving is ≤30 mesh.

[0050] Measuring and packaging: Use an electronic scale with a measuring accuracy of 50g for weighing, and calibrate with a 25kg standard weight before packaging; the net content deviation is controlled within 1%, that is, the net content deviation of 25kg is controlled within 250g.

[0051] Metal inspection: Use standard test blocks (iron φ≤2.0mm, stainless steel φ≤2.5mm) for calibration; test the machine with standard test blocks every 2 hours.

[0052] After passing the inspection, the finished products will be packed and put into storage: Inspect according to the inspection procedures, and the finished products will be put into storage after passing the inspection.

[0053] The polyglycerol ester products were prepared according to the preparation processes described in Examples 1-3 and Comparative Examples 1-3, and their quality parameters were measured and shown in the following table.

[0054] Table 1: Parameters of polyglycerol esters obtained by the present invention

[0055]

[0056] It can be seen from Table 1 that the present invention fully meets the indicators listed in the quality standard compared with the quality standard. However, the saponification value of Comparative Example 1 is lower than the standard, the saponification value of Comparative Example 2 is higher than the standard, and the appearance, saponification value, ignition residue, and melting point of Comparative Example 3 do not meet the indicators of the quality standard. Therefore, the products obtained in Comparative Examples 1-3 do not meet the quality standard, while the indicators of the products obtained in Examples 1-3 meet the quality standard.

[0057] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing polyglycerol esters, comprising the steps of: (1) Take glycerol, adjust the pH value to 3-4, add a composite catalyst, polymerize, and obtain polyglycerol; (2) in a bubbling reactor system, the fatty acid and the polyglycerol obtained in step (1) are reacted to synthesize polyglycerol ester under the catalysis of immobilized lipase; in, In step (1), the composite catalyst is composed of cutinase and lipase in a mass ratio of 1:1-3, the mass ratio of glycerol to the composite catalyst is 90-100:1-2, the polymerization time is 2-6h, and the polymerization temperature is 20-40°C; in step (2), the immobilized lipase is immobilized on silica gel to form a silica gel-loaded lipase system, the mass ratio of the immobilized lipase to the substrate fatty acid-polyglycerol is 15-25:1000, and the fatty acid is one or a mixture of stearic acid, capric acid, lauric acid, myristic acid, and oleic acid.

2. The preparation method of polyglycerol ester as claimed in claim 1, characterized in that, The air flow rate of the bubbling reactor in step (2) is 4-7 L / min.

3. The preparation method of polyglycerol ester as claimed in claim 1, characterized in that, The mass fraction of the immobilized lipase in the silica gel-loaded lipase system in step (2) is 30-50%.

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