Method for preparing diacylglycerol

Abstract

A method for preparing diacylglycerol. The method comprises: under normal pressure, adding lipase into a reaction substrate for a reaction to obtain a first product, wherein the reaction substrate comprises the following components in parts by weight: 80-90 parts of grease, 5-10 parts of glycerol and 5-10 parts of a lower alcohol; at 100-1,000 Pa, making the first product to continue to react to obtain a second product; and removing non-diacylglycerol and non-triacylglycerol components from the second product to obtain diacylglycerol oil.

Description

A method for preparing diglyceride Technical Field

[0001] The present disclosure relates to the field of edible oil processing, and in particular to a method for preparing diglyceride oil. Background Art

[0002] Diacylglycerol (DAG) is a structural lipid in which one fatty acid in a triglyceride (TAG) is replaced by a hydroxyl group. DAG is a trace component of natural plant oils and fats and an endogenous intermediate in fat metabolism. It is a recognized safe food ingredient. Currently, commonly used DAG synthesis methods are mainly divided into chemical and enzymatic methods. Traditional chemical methods often use alkali (such as potassium hydroxide and sodium hydroxide) as catalysts and react at high temperatures. This is energy-intensive, the reaction product contains relatively low DAG content, and it is not suitable for the preparation of DAG rich in polyunsaturated fatty acids. In contrast, enzymatic reactions offer advantages such as mild reaction conditions, strong selectivity, environmental friendliness, low energy consumption, and few byproducts. Therefore, enzymatic methods are gaining increasing attention. Depending on the reaction route, DAG can be prepared through glycerolysis, partial hydrolysis of glycerol, direct esterification of glycerol, and transesterification of glycerol with fatty acid methyl / ethyl esters.

[0003] Enzymatic esterification refers to the reaction of free fatty acids with glycerol to produce DAG, as well as some monoglycerides (MAG) and triglycerides (TAG) under the catalysis of lipase. The reaction route is as follows:

[0004] Because the reaction is reversible, a key to synthesizing DAG through esterification is the timely removal of the water generated. An appropriate water content is required to maintain enzyme activity, while excess water can hinder the esterification reaction. Therefore, the generated water must be removed promptly throughout the reaction. However, to maintain the enzyme's catalytic activity, the system must also maintain a certain amount of water. Therefore, maintaining water balance throughout the system is a major challenge in enzymatic esterification. Furthermore, most enzymatic esterification syntheses utilize solvent-free systems. However, due to the poor solubility of glycerol and fatty acids, glycerol tends to coat the enzyme surface, hindering its contact with the substrate fatty acid, resulting in a slow reaction.

[0005] Enzymatic glycerolysis refers to the reaction of TAG with glycerol under the catalysis of free or immobilized enzymes. It is the main reaction pathway for the preparation of glycerides (MAG and DAG). The reaction route is as follows:

[0006] However, since the glycerolysis reaction is a continuous multi-step reaction and DAG is an intermediate product of the reaction, it is difficult to adjust the reaction process so that the reaction product remains in the DAG stage, that is, it is difficult to improve the selectivity of the reaction for DAG, resulting in a low DAG yield and a high by-product content. At the same time, because triglycerides cannot be completely alcoholyzed, the diglyceride content in the final product is low.

[0007] Enzymatic hydrolysis mainly refers to the partial hydrolysis of TAG under the action of enzymes to release fatty acids (FFA). The generated products are DAG and MAG. Complete hydrolysis will produce glycerol and FFA. By controlling the reaction conditions (such as water content), a certain amount of DAG can be obtained. The reaction route is as follows:

[0008] The hydrolysis method for preparing DAG is simple and does not require the addition of other substrates; however, the reaction conditions need to be controlled to prevent excessive hydrolysis, and the FFA contained in the product needs to be further separated, resulting in a low DAG yield.

[0009] In order to increase the DAG yield, patent document CN 202110760329.8 discloses a two-step enzymatic method for preparing diglycerides. In the first step, lipase catalyzes the reaction of lower alcohols with oils. In the second step, glycerol is added without removing the lower alcohols to carry out an enzyme-catalyzed reaction. This scheme can produce diglycerides with a higher yield. However, this scheme is a two-step method, and the lower alcohol and enzyme preparation need to be recovered in the middle. At the same time, this scheme is applied to two different enzyme preparations. Different reaction conditions need to be adjusted according to different enzymes during the reaction, and the operation is cumbersome. In addition, this scheme takes a long time in the alcoholysis stage, which is not conducive to reducing costs.

[0010] After diglycerides are synthesized, the mixture typically contains non-diaceryl components such as free fatty acids, monoglycerides, and triglycerides. Under certain processes, it may also contain lower alcohol esters of fatty acids. By removing low-molecular-weight free fatty acids, monoglycerides, and lower alcohol esters of fatty acids through single molecular distillation, the remaining diglycerides and triglycerides can be used as diglyceride oil. That is, the sum of the diglyceride and triglyceride contents in the mixture after the reaction as a proportion of the total mixture can be used as the yield of diglyceride oil. Therefore, when preparing diglyceride oil, it is important to pay attention not only to the diglyceride production rate but also to the triglyceride production amount. In other words, minimizing the production of non-triglyceride and non-diaceryl components is crucial to improving the yield of diglyceride oil.

[0011] In summary, it is necessary to find a method for preparing diglyceride oil that can increase the yield of diglyceride oil, is simple to operate and takes a short time.

[0012] Summary of the Invention

[0013] One aspect of the present disclosure is to provide a method for preparing diglyceride oil, which is simple to operate, takes a short preparation time, and has a high diglyceride content in the final product.

[0014] The present disclosure provides a method for preparing diglyceride oil, comprising: adding lipase to a reaction substrate under normal pressure to carry out a reaction to obtain a first product, wherein the reaction substrate comprises the following components in parts by weight: 80-90 parts of oil, 5-10 parts of glycerol, and 5-10 parts of lower alcohol; allowing the first product to continue reacting under 100-1000 Pa to obtain a second product; and removing non-diaceryl and non-triglyceryl from the second product to obtain diglyceride oil.

[0015] The present invention discloses a method for preparing a diglyceride oil by mixing oil, glycerol, and a lower alcohol as reaction substrates, first reacting them under normal pressure and then under vacuum under the catalysis of lipase. By controlling the amounts of the various substances in the reaction substrates and the reaction conditions, the yield of diglyceride oil in the product can be increased. The preparation method disclosed herein has a simple process, is easy to operate, requires a short reaction time, reduces production costs, and achieves a high yield of diglyceride oil.

[0016] In some embodiments, the mass ratio of the glycerol to the lower alcohol is 1:(1-3).

[0017] In some embodiments, the lower alcohol is selected from at least one of methanol, ethanol, propanol, and butanol.

[0018] In some embodiments, the oil is selected from at least one of animal oil and vegetable oil.

[0019] In some embodiments, the lipase accounts for 0.5-5% of the total mass of the reaction substrate.

[0020] In some embodiments, at normal pressure, the reaction temperature is 55-65° C., and the reaction time is 1-5 h.

[0021] In some embodiments, at 100-1000 Pa, the reaction temperature is 55-65° C., and the reaction time is 1-3 h.

[0022] In some embodiments, the removing step is performed by molecular distillation.

[0023] In some embodiments, the reaction is carried out under stirring conditions.

[0024] In some embodiments, the theoretical yield of diglyceride oil in the second product is not less than 70%, and the theoretical content of diglycerides is not less than 60%. Here, theoretical yield of diglyceride oil = diglyceride content + triglyceride content; theoretical content of diglycerides = diglyceride content / (diglyceride content + triglyceride content).

[0025] Another aspect of the present disclosure further provides a diglyceride oil prepared by the above-mentioned method for preparing diglyceride oil.

[0026] The present disclosure has the following beneficial effects: the preparation process is simple, the operation is convenient, and the reaction time is short. The preparation method of the present disclosure has a high yield of diglyceride oil. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present disclosure to clearly and completely describe the technical solutions of the present disclosure. Obviously, the embodiments described are part of the embodiments of the present disclosure, but not all of them. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present disclosure.

[0028] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0029] definition:

[0030] Theoretical diglyceride oil yield = diglyceride (DAG) content + triglyceride (TAG) content.

[0031] Theoretical diglyceride content = diglyceride content / (diglyceride content + triglyceride content).

[0032] Example 1:

[0033] 90 g of soybean oil, 5 g of glycerol, 5 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0034] Example 2:

[0035] 80 g of soybean oil, 10 g of glycerol, 10 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0036] Example 3:

[0037] 85 g of soybean oil, 5 g of glycerol, 10 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 65°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 100 Pa, the reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0038] Example 4:

[0039] 85 g of soybean oil, 5 g of glycerol, 5 g of anhydrous ethanol, 5 g of anhydrous methanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 150 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0040] Example 5:

[0041] 85 g of soybean oil, 5 g of glycerol, 10 g of anhydrous butanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 3 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 1000 Pa, the reaction was continued for 2 hours, and the final product was obtained after distillation and purification.

[0042] Example 6:

[0043] 90 g of soybean oil, 5 g of glycerol, 5 g of anhydrous methanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 1000 Pa, the reaction was continued for 1 hour, and the final product was obtained after distillation and purification.

[0044] Example 7:

[0045] 80 g of soybean oil, 10 g of glycerol, 5 g of anhydrous ethanol, 5 g of anhydrous propanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 1 hour, the reactor was vacuumed until the absolute pressure in the reactor reached 1000 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0046] The products obtained after the atmospheric pressure reaction in Examples 1-7 were subjected to single distillation to remove non-diglyceride and non-triglyceride components. The contents of triglycerides, diglycerides, monoglycerides, free fatty acids, and lower alcohol esters in the reaction products were determined. The theoretical yield of diglyceride oil from the single distillation and the theoretical diglyceride content were calculated. The results are shown in Table 1 below.

[0047] The theoretical yield of diglyceride oil and the theoretical content of diglyceride are calculated as follows:

[0048] Theoretical yield of single distillation purified diglyceride oil = DAG content + TAG content.

[0049] Theoretical content of diglyceride purified by single distillation = DAG content / (DAG content + TAG content).

[0050] Table 1: Measurement results of the products and final products after normal pressure reaction of Examples 1-7

[0051] Table 1 clearly shows that the product after the atmospheric pressure reaction has a low diglyceride content and a high content of lower alcohol esters. Compared to the product after the atmospheric pressure reaction, the final product after the vacuum reaction has a significantly higher DAG content, a slightly lower TAG content, and a significantly lower lower alcohol ester content, while maintaining similar free fatty acid and MAG contents. The sum of the DAG and TAG contents increases, while the sum of the non-DAG and non-TAG contents decreases. This demonstrates that the methods of Examples 1-7 improve the yield of diglyceride oil.

[0052] The present disclosure also provides comparative examples 1-9 based on Example 1, and the schemes are as follows.

[0053] Comparative Example 1:

[0054] 50 g of soybean oil, 25 g of glycerol, 25 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa, the reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0055] Comparative Example 2:

[0056] 75 g of soybean oil, 25 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0057] Comparative Example 3:

[0058] 75 g of soybean oil, 25 g of glycerol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0059] Comparative Example 4:

[0060] 75 g of soybean oil, 5 g of glycerol, 20 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0061] Comparative Example 5:

[0062] 80 g of soybean oil, 4 g of glycerol, 16 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0063] Comparative Example 6:

[0064] 95 g of soybean oil, 2 g of glycerol, 3 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa, the reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0065] Comparative Example 7:

[0066] 80 g of soybean oil, 15 g of glycerol, 5 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0067] Comparative Example 8:

[0068] 75 g of soybean oil, 5 g of glycerol, 15 g of anhydrous ethanol and 5 g of Novozymes 435 enzyme were placed in a reactor, the reaction temperature was maintained at 60°C, the stirring rate was 350 r / min, and the reaction was carried out at normal pressure. After the reaction for 5 hours, the reactor was vacuumed until the absolute pressure in the reactor reached 500 Pa. The reaction was continued for 3 hours, and the final product was obtained after distillation and purification.

[0069] Comparative Example 9:

[0070] 90g of soybean oil, 5g of anhydrous ethanol, and 3g of Novozymes 435 enzyme were placed in a reactor. The reaction temperature was maintained at 60°C and the stirring rate was 350r / min. The reaction was carried out under normal pressure. After 5 hours of reaction, the Novozymes 435 enzyme was filtered and recovered. The reaction product was subjected to vacuum distillation to remove residual ethanol, resulting in a fat mixture of partial glycerides and lower alcohol fatty acid esters.

[0071] 5 g of glycerol was added to the oil composition, and 2 g of Novozymes 435 enzyme was added to catalyze the reaction. The reaction temperature was controlled at 60° C. and the reaction was carried out for 3 h under magnetic stirring. The pressure of the reaction system was controlled at 500 Pa. After the reaction was completed, the Novozymes 435 enzyme was filtered and recovered, and the product was purified by distillation to obtain the final product.

[0072] The product obtained after the atmospheric pressure reaction in Comparative Examples 1-8 was subjected to single distillation to remove non-diglyceride and non-triglyceride components. The triglyceride, diglyceride, monoglyceride, free fatty acid, and lower alcohol ester contents of the reaction product were determined. The theoretical yield of single distillation diglyceride oil and its theoretical diglyceride content were calculated. The calculation method was the same as in Examples 1-7. The results are shown in Table 2 below.

[0073] Table 2: Test results of the products obtained after the reaction at normal pressure of Comparative Examples 1-8 and the final products of Comparative Examples 1-9

[0074] As can be seen from the data in Tables 1 and 2, the theoretical yield of diglyceride oil in the final products prepared by the methods of Examples 1-7 is not less than 70%, and the theoretical content of diglyceride is not less than 60%. In Comparative Examples 1-9, the theoretical yield of diglyceride oil in the final products prepared is relatively lower than that of the Examples.

Claims

1. A method for preparing diglyceride oil, comprising: Adding lipase to a reaction substrate under normal pressure to carry out a reaction to obtain a first product, wherein the reaction substrate comprises the following components in parts by weight: 80-90 parts of oil, 5-10 parts of glycerin, and 5-10 parts of lower alcohol; allowing the first product to continue reacting at 100-1000 Pa to obtain a second product; Non-diglycerides and non-triglycerides are removed from the second product to obtain a diglyceride oil.

2. The preparation method according to claim 1, wherein The mass ratio of the glycerol to the lower alcohol is 1:(1-3).

3. The preparation method according to claim 1 or 2, wherein The lower alcohol is selected from at least one of methanol, ethanol, propanol and butanol.

4. The preparation method according to claim 1 or 2, wherein The oil is selected from at least one of animal oil and vegetable oil.

5. The preparation method according to claim 1 or 2, wherein The lipase accounts for 0.5-5% of the total mass of the reaction substrate.

6. The preparation method according to claim 1 or 2, wherein Under normal pressure, the reaction temperature is 55-65° C. and the reaction time is 1-5 h.

7. The preparation method according to claim 1 or 2, wherein At 100-1000 Pa, the reaction temperature is 55-65° C. and the reaction time is 1-3 h.

8. The preparation method according to claim 1 or 2, wherein The removal step is performed by molecular distillation.

9. The preparation method according to claim 1, wherein The reaction is carried out under stirring conditions.

10. The preparation method according to claim 1, wherein The theoretical yield of diglyceride oil in the second product is not less than 70%, and the theoretical content of diglyceride is not less than 60%.

11. Diglyceride oil prepared by the preparation method according to any one of claims 1 to 10.

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