Preparation method of diglyceride grease

Abstract

The invention discloses a preparation method of diglyceride, and belongs to the technical field of grease processing. The method comprises the following steps: carrying out glycerolysis reaction on grease and glycerol, purifying by molecular distillation to obtain light-phase distilled monoester, reacting the light-phase distilled monoester under the action of enzyme to obtain a reaction product containing glycerol, monoglyceride, diglyceride and triglyceride, and purifying the reaction product by molecular distillation to obtain the diglyceride grease. According to the preparation method, the triglyceride grease rich in source is adopted as the raw material, fatty acid does not need to be added, no by-product is generated, and cost is saved; the method does not need to use an organic solvent, and the preparation process is pollution-free; and the yield of the diglyceride prepared by using the method is high, and the content of the 1, 3-diglyceride in the prepared diglyceride is high.

Description

Technical Field

[0001] This application relates to the technical field of oil processing, and particularly relates to a method for preparing diacylglycerol oil. Background Art

[0002] Diacylglycerol (DAG) is a structural lipid in which one fatty acid in a class of triacylglycerols (TAG) is replaced by a hydroxyl group. It is a natural component of various edible oils and mainly exists in two isomers: 1,3-DAG and 1,2(2,3)-DAG. However, its content in natural animal and vegetable oils is extremely low, generally less than 10%. For example, olive oil contains 5.5% diacylglycerol, and cottonseed oil contains 9.5%. Nutritionists have found that 1,3-DAG not only has different metabolic characteristics from triacylglycerols but also has a significant effect on the prevention and treatment of obesity. It is rarely accumulated in the body after ingestion, can reduce the lipid content in the blood, and can be used for the prevention and treatment of hyperlipidemia and cardiovascular and cerebrovascular diseases closely related to hyperlipidemia.

[0003] The preparation methods of diacylglycerol mainly include hydrolysis method, esterification method, and glycerolysis method. The hydrolysis method uses triacylglycerol as a substrate and selects 1,3 as the lipase for partial hydrolysis to prepare diacylglycerol by controlling the degree of hydrolysis. Patent Application No. CN201510980040 discloses a method for preparing diacylglycerol by enzymatic catalysis, which first moderately hydrolyzes the oil and then adds the hydrolysis product to glycerol for esterification. The content of diacylglycerol in the obtained product is 60% - 65%. Moreover, this preparation technology requires strict control of the fatty acid content in the hydrolysis process to be between 26% - 30%, and the controllable range is very narrow. Improper control may cause over-hydrolysis of diacylglycerol, producing more fatty acids and reducing the purity of diacylglycerol.

[0004] The esterification method is to enzymatically catalyze the reaction of fatty acids and glycerol to obtain a product containing diglycerides, which is usually used to prepare diglyceride oil with a content of more than 80%. However, high-purity fatty acids need to be prepared before esterification. Compared with other preparation methods, the preparation process of this method is usually more complex, which will increase the preparation cost and the difficulty of reaction control to a certain extent. Moreover, the formation of triglycerides during the esterification process greatly reduces the purity of diglycerides. Since triglycerides and diglycerides are difficult to separate, a very high distillation temperature is required to separate them by molecular distillation. Therefore, the content of triglycerides affects the purity of diglycerides. Application No. CN201310255990 discloses a method for preparing diglycerides by esterification. At a certain temperature, medium and long-chain fatty acids and glycerol are mixed at a molar ratio of 1.5 - 2.1:1 and reacted through the action of lipase to obtain a product containing diglycerides. The reaction product is purified by two-stage molecular distillation, and the two-stage purification temperature is 200 - 220°C. However, if distilling long-chain diglycerides, the required temperature will be 230°C - 250°C, and the high distillation temperature poses a risk of forming glycidyl esters.

[0005] The glycerolysis method uses glycerol and triglycerides as substrates to obtain a reaction product containing monoglycerides, diglycerides and triglycerides through a catalytic glycerolysis reaction. Then, the monoglycerides are removed by molecular distillation to obtain diglyceride oil. The reaction can use chemical catalysts or enzymatic methods. In the chemical glycerolysis reaction, inorganic alkaline catalysts are usually used. Under the protection of inert gas or under vacuum conditions, triglycerides are reacted with excess glycerol to obtain about 40% - 50% monoglycerides and about 40% diglycerides. The reaction time is short, generally 4 - 5 hours. After molecular distillation, light-phase distilled monoglycerides and heavy-phase diglyceride oils are obtained. Since the reaction is carried out at high temperature and the diglycerides obtained by molecular distillation are in the heavy phase, the diglyceride oil has a darker color and has unpleasant odors such as a burnt smell. Enzymatic glycerolysis uses lipase to react under mild conditions. However, due to the poor miscibility of glycerol and triglycerides, the reaction time is long, the preparation efficiency is low, and the content of diglycerides is low (used to prepare diglyceride oil with a content of more than 40%). Therefore, it is relatively difficult to prepare high-purity diglycerides by a single preparation method, and multiple technical means need to be coordinated for preparation.

[0006] Enzymatic lipid modification includes solvent systems and solvent-free systems. Adding organic solvents can increase the miscibility of substrates, reduce the viscosity of the reaction system, and improve the reaction efficiency. However, most organic solvents are flammable and explosive (such as ethanol, n-hexane, etc.), posing safety hazards during use and storage. At the same time, they are highly volatile, pollute the environment, and are toxic to the human body; and there is a risk of residue during application. In the food industry and production safety requirements limit the application of solvent systems in actual production.

[0007] Therefore, a new method for preparing diglyceride is needed, which can meet the requirements of high yield of diglyceride, especially 1,3-diglyceride, simple preparation method, and safe and environmentally friendly process. Summary of the Invention

[0008] The purpose of this application is to provide a method for preparing diglyceride. This method has simple preparation steps, does not require additional addition of fatty acids and organic solvents during the preparation process, saves costs and is safe and environmentally friendly; the yield of diglyceride by this method is high, and the content of 1,3-diglyceride in the obtained diglyceride is high.

[0009] To achieve the above invention purpose, the following technical solutions are adopted.

[0010] A method for preparing diglyceride oil and fat, comprising the following steps:

[0011] React oil B under the action of an enzyme to obtain reaction oil D;

[0012] Perform molecular distillation on reaction oil D to obtain heavy-phase oil F;

[0013] Among them, the components of oil B include monoglyceride, and the acid value is less than 2 mg KOH / g; oil F is diglyceride.

[0014] In some aspects of this application, the method for preparing diglyceride further includes:

[0015] Perform glycerolysis reaction on oil and glycerol to obtain reaction oil A;

[0016] Perform molecular distillation on reaction oil A to obtain light-phase oil B;

[0017] Among them, the above-mentioned oil B includes light-phase oil B.

[0018] In some aspects of this application, light-phase oil B is monoglyceride.

[0019] In some aspects of this application, heavy-phase oil C includes diglyceride and triglyceride.

[0020] In some aspects of this application, the preparation of diglyceride further includes the following steps:

[0021] Perform glycerolysis reaction on heavy-phase oil C by adding glycerol to obtain reaction oil A; and / or

[0022] The method for preparing diglyceride further includes the following steps:

[0023] Perform molecular distillation on reaction oil D to obtain light-phase oil E and heavy-phase oil F;

[0024] React light-phase oil E under the action of an enzyme to obtain reaction oil D.

[0025] In some aspects of the present application, the glycerolysis reaction includes chemical glycerolysis.

[0026] In some aspects of the present application, the addition amount of glycerol in the glycerolysis reaction is 8-15 wt% of the weight of the oil and fat.

[0027] In some aspects of the present application, the catalyst used in the chemical glycerolysis includes at least one of the following:

[0028] NaOH, KOH, Ca(OH)2, sodium stearate, calcium stearate.

[0029] In some aspects of the present application, the chemical glycerolysis reaction is carried out for 3.5-6 h under vacuum or inert gas protection; the reaction temperature is 180°C to 230°C.

[0030] In some aspects of the present application, the temperature of molecular distillation is 140-180°C; the vacuum degree is 1.0×10 -2 ~1.0×10 -3 mbar.

[0031] In some aspects of the present application, the light-phase oil and fat B obtained by molecular distillation includes two-step molecular distillation.

[0032] In some aspects of the present application, the two-step molecular distillation includes: first, molecular distillation is used to remove fatty acids and excess glycerol, and then molecular distillation is carried out to obtain the light-phase oil and fat B.

[0033] In some aspects of the present application, the oil and fat for the glycerolysis reaction is vegetable oil.

[0034] In some aspects of the present application, the vegetable oil includes at least one of soybean oil, sunflower oil, olive oil, palm oil, and corn oil.

[0035] In some aspects of the present application, the enzyme is lipase.

[0036] In some aspects of the present application, the lipase is immobilized Candida antarctica lipase B (Candida Antarctic B).

[0037] In some aspects of the present application, the addition amount of the enzyme is 1-6 wt%.

[0038] In some aspects of the present application, the reaction temperature of the enzyme is 50°C to 70°C, and the reaction time is 1-4 hours.

[0039] The present application also discloses diglycerides prepared by the above method.

[0040] In some aspects of the present application, the content of 1,3-diglyceride in the prepared diglyceride accounts for more than 80 wt% of the total amount.

[0041] Compared with the prior art, the beneficial effects of the present application are as follows:

[0042] In the present application, the glycerolysis reaction is carried out with oil and glycerol, and the light-phase distilled monoglyceride is obtained by molecular distillation purification. The light-phase distilled monoglyceride is then subjected to an ester-ester exchange reaction under the action of an enzyme to obtain a reaction product containing glycerol, monoglyceride, diglyceride and triglyceride. The reaction product is purified by molecular distillation to obtain diglyceride. The raw materials of the preparation method of the present application are rich in sources, and no fatty acid needs to be added, saving costs; this method does not need to use organic solvents and there is no pollution in the preparation process; moreover, the yield of diglyceride prepared by this method is high (more than 65%), and the content of 1,3-diglyceride is high (more than 80% of diglyceride). Detailed implementation manners

[0043] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0044] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall in no way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0045] In this article, all features defined in the form of numerical ranges or percentage ranges, such as quantity, content and concentration, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual values within the range (including integers and fractions). In this article, unless otherwise specified, the percentage is the mass percentage.

[0046] In this article, for the sake of concise description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0047] In some embodiments of the present application, the method for preparing diglyceride oil and fat specifically includes the following steps:

[0048] React the oil and fat B under the action of an enzyme to obtain a reaction oil and fat D;

[0049] Perform molecular distillation on the reaction oil and fat D to obtain a heavy-phase oil and fat F;

[0050] Among them, the oil and fat B component includes monoglyceride with an acid value less than 2 mg KOH / g; the oil and fat F is diglyceride.

[0051] In some embodiments of the present application, the reaction oil and fat D is subjected to molecular distillation to obtain a light-phase oil and fat E and a heavy-phase oil and fat F.

[0052] In some embodiments of the present application, the method for preparing diglyceride oil and fat further includes the following steps:

[0053] The oil and fat and glycerol are subjected to glycerolysis reaction to obtain a reaction oil and fat A;

[0054] The reaction oil and fat A is subjected to molecular distillation to obtain a light-phase oil and fat B;

[0055] Among them, the above-mentioned oil and fat B includes the light-phase oil and fat B.

[0056] In some embodiments of the present application, the glycerolysis reaction is a chemical glycerolysis.

[0057] In some embodiments of the present application, the glycerolysis reaction is an enzymatic glycerolysis.

[0058] In some embodiments of the present application, the addition amount of glycerol in the glycerolysis reaction is 8-15 wt% of the weight of the oil and fat. The amount of glycerol used in the present application is beneficial to the synthesis of monoglyceride.

[0059] In some embodiments of the present application, the addition amount of glycerol in the glycerolysis reaction is 9-14.5 wt% of the weight of the oil and fat.

[0060] In some embodiments of the present application, the addition amount of glycerol in the glycerolysis reaction is 10 wt% of the weight of the oil and fat.

[0061] In some embodiments of the present application, the catalyst used in the chemical glycerolysis includes at least one of the following:

[0062] NaOH, KOH, Ca(OH)2, sodium stearate, calcium stearate.

[0063] In some embodiments of the present application, the chemical glycerolysis reacts for 3.5-6 h under vacuum or inert gas protection; the reaction temperature is 180°C to 230°C.

[0064] In some embodiments of the present application, the chemical glycerolysis first rises to 180°C for reaction under vacuum or inert gas protection, and then rises to 210°C for reaction. Two-stage heating can reduce the energy consumption required for heating and save costs.

[0065] In some embodiments of the present application, the specific operation of the chemical glycerolysis is as follows:

[0066] Weigh the oil and glycerol and add them to the reaction kettle. Add a catalyst to the reaction kettle. Under vacuum or inert gas protection, quickly heat the reaction kettle to 180 °C to 230 °C, react for 2 to 6 hours, and then cool to room temperature to obtain the reacted oil A; or

[0067] Weigh the oil and glycerol and add them to the reaction kettle. Add a catalyst to the reaction kettle. Under vacuum or inert gas protection, quickly heat the reaction kettle to 180 to 210 °C, react for 2 to 6 hours, then raise the temperature of the reaction kettle to 210 to 230 °C and react for 2 to 6 hours, and then cool to room temperature to obtain the reacted oil A.

[0068] In some embodiments of the present application, the temperature of molecular distillation is 140 to 180 °C; the vacuum degree is 1.0×10 -2 ~1.0×10 -3 mbar.

[0069] In some embodiments of the present application, the light-phase oil B is monoglyceride.

[0070] The present application controls the acid value of the obtained light-phase oil B through molecular distillation, that is, the acid value of the obtained monoglyceride is less than 2 mg KOH / g. Using monoglyceride with an acid value less than 2 mg KOH / g to participate in the subsequent reaction steps is beneficial to improving the yield of diglyceride, especially 1,3-diglyceride.

[0071] In some embodiments of the present application, the heavy-phase oil C includes diglyceride and triglyceride.

[0072] In some embodiments of the present application, the step of subjecting the reacted oil A to molecular distillation to obtain the light-phase oil B and the heavy-phase oil C includes two steps of molecular distillation.

[0073] In some embodiments of the present application, the above two steps of molecular distillation include: first, molecular distillation is used to remove fatty acids and excess glycerol, and then molecular distillation is carried out to obtain the light-phase oil B and the heavy-phase oil C.

[0074] In some embodiments of the present application, the specific operation of molecular distillation to obtain the light-phase oil B and the heavy-phase oil C is as follows:

[0075] Subject the reacted oil A to molecular distillation under a vacuum degree of 1.0×10 -2 ~1.0×10 -3 mbar and a distillation temperature of 140 to 160 °C to remove fatty acids and excess glycerol, and then carry out molecular distillation under a vacuum degree of 1.0×10 -2 ~1.0×10 -3 mbar and a distillation temperature of 160 to 180 °C to obtain the distilled light-phase oil B and the distilled heavy-phase oil C.

[0076] In some embodiments of the present application, the preparation of diglyceride further comprises the following steps:

[0077] Subject the reaction oil A to molecular distillation to obtain a light-phase oil B and a heavy-phase oil C;

[0078] React the heavy-phase oil C with glycerol through glycerolysis to obtain the reaction oil A; and / or

[0079] The method for preparing diglyceride further comprises the following steps:

[0080] Subject the reaction oil D to molecular distillation to obtain a light-phase oil E and a heavy-phase oil F;

[0081] React the light-phase oil E under the action of an enzyme to obtain the reaction oil D.

[0082] In some embodiments of the present application, the enzyme is lipase.

[0083] In some embodiments of the present application, the lipase is immobilized Candida antarctica lipase B.

[0084] In some embodiments of the present application, the addition amount of the enzyme is 1-6 wt% of the oil.

[0085] In some embodiments of the present application, the addition amount of the enzyme is 2-6 wt% of the oil.

[0086] In some embodiments of the present application, the addition amount of the enzyme is 3-6 wt% of the oil.

[0087] In some embodiments of the present application, the addition amount of the enzyme is 4-6 wt% of the oil.

[0088] In some embodiments of the present application, the reaction temperature of the enzyme is 50°C - 70°C.

[0089] In some embodiments of the present application, the reaction time of the enzyme is 1-4 hours.

[0090] In some embodiments of the present application, the reaction temperature of the enzyme is 55°C - 65°C.

[0091] In some embodiments of the present application, the reaction time of the enzyme is 1.5-3.5 hours.

[0092] In some embodiments of the present application, the reaction temperature of the enzyme is 50°C - 60°C.

[0093] In some embodiments of the present application, the reaction time of the enzyme is 2-2.5 hours.

[0094] In some embodiments of the present application, the specific operation for obtaining the reaction oil D from the oil B under the action of the enzyme is:

[0095] Weigh the oil B and add it to the reaction vessel, then add immobilized Candida antarctica lipase B, and react at a temperature of 50-70 °C for 1-4 hours. After the reaction, filter to remove the enzyme and centrifuge to remove glycerol to obtain the reaction oil D.

[0096] In some embodiments of the present application, the specific operation of obtaining the reaction oil D by reacting the light-phase oil E under the action of an enzyme is as follows:

[0097] Weigh the light-phase oil E and add it to the reaction vessel, then add immobilized Candida antarctica lipase B, and react at a temperature of 50-70 °C for 1-4 hours. After the reaction, filter to remove the enzyme and centrifuge to remove glycerol to obtain the reaction oil D.

[0098] In some embodiments of the present application, the immobilized Candida antarctica lipase B includes Novozym 435 enzyme.

[0099] In some embodiments of the present application, the oil for glycerolysis reaction is vegetable oil.

[0100] In some embodiments of the present application, the vegetable oil includes at least one of soybean oil, sunflower oil, olive oil, palm oil, and corn oil.

[0101] In some embodiments of the present application, the specific operation of obtaining the light-phase oil E and the heavy-phase oil F by molecular distillation is as follows:

[0102] The reaction oil D is subjected to molecular distillation under a vacuum of 1.0×10 -2 ~1.0×10 -3 mbar and a distillation temperature of 160-180 °C to obtain the distilled light-phase oil E and the distilled heavy-phase diglyceride oil F.

[0103] The present application also discloses diglycerides prepared by the above method.

[0104] In some aspects of the present application, the content of 1,3-diglyceride in the prepared diglyceride accounts for more than 80% of the total amount.

[0105] In some aspects of the present application, the content of 1,3-diglyceride in the prepared diglyceride accounts for more than 85% of the total amount.

[0106] The present invention will be further described below by way of examples, but the scope of the present invention is not limited by the content of the following examples. The protection scope of the present invention is only defined by the claims, and any omission, substitution, or modification made by those skilled in the art based on the disclosed embodiments of the present invention will fall within the protection scope of the present invention.

[0107] Conventional instrumentation and equipment in the art are used in the following examples. For the experimental methods without specific conditions noted in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following examples, and unless otherwise specified, they are all commercially available products. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0108] In the following examples and comparative examples, sodium hydroxide (AR, Shanghai Reagent), potassium hydroxide (AR, Shanghai Reagent), calcium hydroxide (AR, Shanghai Reagent), sodium stearate (CP, Shanghai Reagent), calcium stearate (AR, Shanghai Reagent), glycerol (glycerol) (AR, Shanghai Reagent), olive oil (CP, Shanghai Reagent), oleic acid (CP, Shanghai Reagent) were all purchased from Sinopharm Group; Novozym 435 enzyme (immobilized Candida antarctica lipase B), Novozym RM C enzyme (immobilized Rhizomucor miehei lipase), Novozym TL IM enzyme (immobilized Thermomyces lanuginosus lipase) were all purchased from Novozymes; immobilized DF Amano 15 enzyme (immobilized Rhizopus oryzae lipase) was purchased from Amano Enzyme Co., Ltd., Japan; glycerol monooleate (product number PHR1484), 1,2-diolein (product number 0138; ≥97%), 1,3-diolein (product number 3627; ≥99%), triolein (product number 92860; ≥97%) were all purchased from Sigma-Aldrich.

[0109] In the following examples and comparative examples, the acid value was determined according to the method in GB / T 5009.37.

[0110] In the following examples and comparative examples, the detection method for the content of diglycerides in oils and fats: Take about 20 - 25 mg of the oil and fat sample, add 1.5 ml of the mobile phase to dissolve and mix evenly, and analyze it by a waters high-performance liquid chromatography equipped with a differential detector. The injection volume is 10 μl, the chromatographic column: Phenomenex Luna Silica (2) (4.6 mm i.d.×250 mm×5 μm), the mobile phase: the volume ratio of n-hexane: isopropanol: formic acid is 18:1:0.003, the flow rate is 1 ml / min, and the column oven temperature is 35 °C. Different components are qualitatively analyzed using standard products, and the content of each component is quantified by the area normalization method. The content of diglycerides in oils and fats (mass content) is the sum of 1,3-diglyceride and 1,2-diglyceride. The percentage ratio of 1,3-diglyceride is the content of 1,3-diglyceride / the content of diglycerides in oils and fats.

[0111] Example 1

[0112] Weigh 4000 g of soybean oil (Yihai Kerry Group) and 400 g of glycerol and add them to a reaction kettle. Add 4 g of sodium hydroxide to the reaction kettle. Under vacuum, quickly heat the reaction kettle to 180 °C and react for 2 hours. Then raise the temperature of the reaction kettle to 210 °C, react for 2 hours, and then cool down to room temperature to obtain reaction oil A1-1; Subject reaction oil A1-1 to molecular distillation at a vacuum of 1.0×10 - 3 mbar and a distillation temperature of 145 °C to remove fatty acids and excess glycerol. Then, perform molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain distilled light-phase oil B1-1 and distilled heavy-phase oil C1-1. The acid value of distilled light-phase oil B1-1 is measured to be 0.65 mg KOH / g.

[0113] Weigh 250 g of oil B1-1 and add it to a 500 ml three-necked flask. Then add 7.5 g of Novozym 435 enzyme from Novozymes and react at 60 °C for 4 hours. Filter to remove Novozym 435 enzyme and centrifuge to remove glycerol to obtain reaction oil D1-1. Subject reaction oil D1-1 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain distilled light-phase oil E1-1 and distilled heavy-phase diglyceride oil F1-1. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F1-1 are shown in Table 1.

[0114] Example 2

[0115] Weigh 4000 g of 24-degree palm oil (Yihai Kerry Group) and 450 g of glycerol and add them to a reaction kettle. Add 4 g of potassium hydroxide to the reaction kettle. Under N2 protection, quickly heat the reaction kettle to 210 °C and react for 4 hours, and then cool down to room temperature to obtain reaction oil A1-2; Subject reaction oil A1-2 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 140 °C to remove fatty acids and excess glycerol. Then, perform molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 160 °C to obtain distilled light-phase oil B1-2 and distilled heavy-phase oil C1-2. The acid value of distilled light-phase oil B1-2 is measured to be 1.23 mg KOH / g.

[0116] Weigh 250 g of oil B1-2 and add it to a 500 ml three-necked flask. Then add 10 g of Novozym 435 enzyme and react at 70 °C for 1.5 hours. Filter to remove Novozym 435 enzyme, and centrifuge to remove glycerol to obtain reaction oil D1-2. Subject the reaction oil D1-2 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 165 °C to obtain distilled light-phase oil E1-2 and distilled heavy-phase diglyceride oil F1-2. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F1-2 are shown in Table 1.

[0117] Example 3

[0118] Weigh 4000 g of sunflower oil (Yihai Kerry Group) and 400 g of glycerol and add them to a reaction kettle. Add 3.5 g of calcium hydroxide to the reaction kettle, quickly heat the reaction kettle to 200 °C under vacuum, react for 6 hours, and then cool to room temperature to obtain reaction oil A1-3; Subject the reaction oil A1-3 to molecular distillation at a vacuum of 1.0×10 -2 mbar and a distillation temperature of 160 °C to remove fatty acids and excess glycerol, and then subject it to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 180 °C to obtain distilled light-phase oil B1-3 and distilled heavy-phase oil C1-3. The acid value of the distilled light-phase oil B1-3 is measured to be 0.78 mg KOH / g.

[0119] Weigh 250 g of oil B1-3 and add it to a 500 ml three-necked flask. Then add 15 g of Novozym 435 enzyme and react at 55 °C for 1 hour. Filter to remove Novozym 435 enzyme, and centrifuge to remove glycerol to obtain reaction oil D1-3. Subject the reaction oil D1-3 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain distilled light-phase oil E1-3 and distilled heavy-phase oil F1-3. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F1-3 are shown in Table 1.

[0120] Example 4

[0121] Weigh 4000 g of corn oil (Yihai Kerry) and 360 g of glycerol and add them to a reaction kettle. Add 4 g of sodium stearate to the reaction kettle, quickly heat the reaction kettle to 230 °C under N2 protection, react for 3.5 hours, and then cool to room temperature to obtain reaction oil A1-4; Subject the reaction oil A1-4 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 150 °C to remove fatty acids and excess glycerol, and then subject it to molecular distillation at a vacuum of 1.0×10 -3At mbar, molecular distillation was carried out at a distillation temperature of 180 °C to obtain distillate light-phase oil B1-4 and distillate heavy-phase oil C1-4. The acid value of the distillate light-phase oil B1-4 was measured to be 1.05 mg KOH / g.

[0122] Weigh 250 g of oil B1-4 and add it to a 500 ml three-necked flask. Then add 2.5 g of Novozym 435 enzyme and react at a temperature of 50 °C for 4 hours. Filter to remove the Novozym 435 enzyme, and centrifuge to remove glycerol to obtain reaction oil D1-4. React the reaction oil D1-4 under a vacuum of 1.0×10 -3 mbar, molecular distillation was carried out at a distillation temperature of 180 °C to obtain distillate light-phase oil E1-4 and distillate heavy-phase diglyceride oil F1-4. The diglyceride content, 1,3-diglyceride content and 1,3-diglyceride percentage of oil F1-4 are shown in Table 1.

[0123] Example 5

[0124] Weigh 4000 g of olive oil and 480 g of glycerol and add them to the reaction kettle. Add 4 g of calcium stearate to the reaction kettle. Under N2 protection, quickly heat the reaction kettle to 210 °C. After reacting for 4 hours, cool it to room temperature to obtain reaction oil A1-5; React the reaction oil A1-5 under a vacuum of 1.0×10 -3 mbar, molecular distillation was carried out at a distillation temperature of 140 °C to remove fatty acids and excess glycerol, and then under a vacuum of 1.0×10 -3 mbar, molecular distillation was carried out at a distillation temperature of 180 °C to obtain distillate light-phase oil B1-5 and distillate heavy-phase oil C1-5. The acid value of the distillate light-phase oil B1-5 was measured to be 1.95 mg KOH / g.

[0125] Weigh 250 g of oil B1-5 and add it to a 500 ml three-necked flask. Then add 10 g of Novozym 435 enzyme and react at a temperature of 55 °C for 3.5 hours. Filter to remove the Novozym 435 enzyme, and centrifuge to remove glycerol to obtain reaction oil D1-5. React the reaction oil D1-5 under a vacuum of 1.0×10 -3 mbar, molecular distillation was carried out at a distillation temperature of 180 °C to obtain distillate light-phase oil E1-5 and distillate heavy-phase diglyceride oil F1-5. The diglyceride content, 1,3-diglyceride content and 1,3-diglyceride percentage of oil F1-5 are shown in Table 1.

[0126] Example 6

[0127] React the reaction oil A1-5 under a vacuum of 1.0×10 -3 mbar, molecular distillation was carried out at a distillation temperature of 150 °C to remove fatty acids and excess glycerol, and then under a vacuum of 1.0×10 -3At a pressure of mbar, molecular distillation was carried out at a distillation temperature of 180 °C to obtain distillate light-phase oil B1-6 and distillate heavy-phase oil C1-6. The acid value of the distillate light-phase oil B1-6 was measured to be 1.14 mg KOH / g.

[0128] Weigh 250 g of oil B1-6 and add it to a 500-ml three-necked flask. Then add 7.5 g of Novozym 435 enzyme and react at 60 °C for 4 hours. Filter to remove Novozym 435 enzyme, and centrifuge to remove glycerol to obtain reaction oil D1-6. The reaction oil D1-6 was subjected to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 180 °C to obtain distillate light-phase oil E1-6 and distillate heavy-phase diglyceride oil F1-6. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F1-6 are shown in Table 1.

[0129] Example 7

[0130] Weigh 4000 g of 24-degree palm oil (Yihai Kerry Group) and 520 g of glycerol and add them to a reaction kettle. Add 4 g of sodium stearate to the reaction kettle. Under N2 protection, quickly heat the reaction kettle to 200 °C and react for 2 hours. Then raise the temperature of the reaction kettle to 220 °C, react for 2 hours, and then cool to room temperature to obtain reaction oil A1-7. The reaction oil A1-7 was subjected to molecular distillation at a vacuum of 1.0×10 - 3 mbar to remove fatty acids and excess glycerol at a distillation temperature of 155 °C. Then, at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 165 °C, molecular distillation was carried out to obtain distillate light-phase oil B1-7 and distillate heavy-phase oil C1-7. The acid value of the distillate light-phase oil B1-7 was measured to be 0.94 mg KOH / g.

[0131] Weigh 250 g of oil B1-7 and add it to a 500-ml three-necked flask. Then add 10 g of Novozym 435 enzyme and react at 65 °C for 2.0 hours. Filter to remove Novozym 435 enzyme, and centrifuge to remove glycerol to obtain reaction oil D1-7. The reaction oil D1-7 was subjected to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 165 °C to obtain distillate light-phase oil E1-7 and distillate heavy-phase diglyceride oil F1-7. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F1-7 are shown in Table 1.

[0132] Example 8

[0133] Weigh 4000 g of sunflower oil (Yihai Kerry Group) and 580 g of glycerol and add them to the reaction kettle. Add 4.0 g of sodium hydroxide to the reaction kettle. Quickly heat the reaction kettle to 190 °C under vacuum and react for 2.5 hours. Then raise the temperature of the reaction kettle to 230 °C, react for 1 hour, and then cool down to room temperature to obtain reaction oil A1-8; Distill off fatty acids and excess glycerol from the reaction oil A1-8 by molecular distillation at a vacuum degree of 1.0×10 -2 mbar and a distillation temperature of 160 °C. Then, perform molecular distillation at a vacuum degree of 1.0×10 - 3 mbar and a distillation temperature of 180 °C to obtain distilled light-phase oil B1-8 and distilled heavy-phase oil C1-8. The acid value of the distilled light-phase oil B1-8 is measured to be 0.89 mg KOH / g.

[0134] Weigh 250 g of oil B1-8 and add it to a 500 ml three-necked flask. Then add 15 g of Novozym 435 enzyme from Novozymes and react at 55 °C for 1 hour. Filter to remove the Novozym 435 enzyme and centrifuge to remove glycerol to obtain reaction oil D1-8. Distill the reaction oil D1-8 by molecular distillation at a vacuum degree of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain distilled light-phase oil E1-8 and distilled heavy-phase oil F1-8. The content of diglycerides, the content of 1,3-diglycerides, and the percentage of 1,3-diglycerides in oil F1-8 are shown in Table 1.

[0135] Example 9

[0136] Weigh 1500 g of oil B1-1 from Example 1 and add it to a 3000 ml reaction kettle. Then add 30 g of Novozym 435 enzyme from Novozymes and react at 55 °C for 3.5 hours. Filter to remove the Novozym 435 enzyme and centrifuge to remove glycerol to obtain reaction oil D1-9. Distill off fatty acids and glycerol from the reaction oil D1-9 by molecular distillation at a vacuum degree of 1.0×10 -3 mbar and a distillation temperature of 150 °C. Then, perform molecular distillation at a vacuum degree of 1.0×10 -3 mbar and a distillation temperature of 170 °C to obtain distilled light-phase oil E1-9 and distilled heavy-phase diglyceride oil F1-9. The content of diglycerides, the content of 1,3-diglycerides, and the percentage of 1,3-diglycerides in oil F1-9 are shown in Table 1.

[0137] Example 10

[0138] Weigh 1500 g of the distilled heavy-phase oil C1-1 from Example 1 and 170 g of glycerol, add them to a reaction kettle, add 1.8 g of sodium hydroxide to the reaction kettle, quickly heat the reaction kettle to 220 °C under vacuum conditions, cool it to room temperature after reacting for 4 hours to obtain reaction oil A1-10; subject the reaction oil A1-10 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 155 °C to remove fatty acids and excess glycerol, and then subject it to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 170 °C to obtain distilled light-phase oil B1-10 and distilled heavy-phase oil C1-10. The acid value of the distilled light-phase oil B1-10 is measured to be 0.83 mg KOH / g.

[0139] Weigh 250 g of oil B1-10 and add it to a 500 ml three-necked flask, then add 7.5 g of Novozym 435 enzyme and react at 60 °C for 2.5 hours. Filter to remove the Novozym 435 enzyme, centrifuge to remove glycerol to obtain reaction oil D1-10. Subject the reaction oil D1-10 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 170 °C to obtain distilled light-phase oil E1-10 and distilled heavy-phase diglyceride oil F1-10. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F1-10 are shown in Table 1.

[0140] Example 11

[0141] Weigh 250 g of the distilled light-phase oil E1-9 (acid value 0.96 mg KOH / g) from Example 9 and add it to a 500 ml three-necked flask, then add 7.5 g of Novozym 435 enzyme and react at 55 °C for 3.5 hours. Filter to remove the Novozym 435 enzyme, centrifuge to remove glycerol to obtain reaction oil D1-11. Subject the reaction oil D1-11 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 170 °C to obtain distilled light-phase oil E1-11 and distilled heavy-phase diglyceride oil F1-11. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F1-11 are shown in Table 1.

[0142] Comparative Example 1

[0143] Take 1500 g of the reaction oil A1-1 from Example 1 and subject it to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 125 °C to remove fatty acids and excess glycerol, and then at a vacuum of 1.0×10 -3At a pressure of mbar and a distillation temperature of 175 °C, molecular distillation was carried out to obtain distillate light-phase oil B2-1 and distillate heavy-phase oil C2-1. The acid value of the distillate light-phase oil B2-1 was measured to be 5.42 mg KOH / g.

[0144] Weigh 250 g of oil B2-1 and add it to a 500-ml three-necked flask. Then add 7.5 g of Novozym 435 enzyme and react at 60 °C for 4 hours. Filter to remove the Novozym 435 enzyme, and centrifuge to remove glycerol to obtain reaction oil D2-1. Subject the reaction oil D2-1 to molecular distillation at a vacuum degree of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain distillate light-phase oil E2-1 and distillate heavy-phase diglyceride oil F2-1. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F2-1 are shown in Table 1.

[0145] Comparative Example 2

[0146] Weigh 235 g of the distillate light-phase oil B1-1 in Example 1 into a 500-ml three-necked flask, add 15 g of oleic acid and mix evenly to obtain oil B2-2. The acid value of oil B2-2 was measured to be 11.83 mg KOH / g. Add 7.5 g of Novozym 435 enzyme and react at 60 °C for 4 hours. Filter to remove the Novozym 435 enzyme, and centrifuge to remove glycerol to obtain reaction oil D2-2. Subject the reaction oil D2-2 to molecular distillation at a vacuum degree of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain distillate light-phase oil E2-2 and distillate heavy-phase diglyceride oil F2-2. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F2-2 are shown in Table 1.

[0147] Comparative Example 3

[0148] Weigh 250 g of the distillate light-phase oil B1-1 in Example 1 and add it to a 500-ml three-necked flask. Then add 7.5 g of Novozym RM C enzyme and react at 55 °C for 4 hours. Filter to remove the Novozym RM C enzyme, and centrifuge to remove glycerol to obtain reaction oil D2-3. Subject the reaction oil D2-3 to molecular distillation at a vacuum degree of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain distillate light-phase oil E2-3 and distillate heavy-phase diglyceride oil F2-3. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of oil F2-3 are shown in Table 1.

[0149] Comparative Example 4

[0150] Weigh 250 g of the distilled light-phase oil B1-2 in Example 2 and add it to a 500-ml three-necked flask. Then add 7.5 g of Novozym TL IM enzyme and react at 60 °C for 4 hours. Filter to remove the Novozym TL IM enzyme, and centrifuge to remove glycerol to obtain the reaction oil D2-4. Subject the reaction oil D2-4 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain the distilled light-phase oil E2-4 and the distilled heavy-phase diglyceride oil F2-4. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of the oil F2-4 are shown in Table 1.

[0151] Comparative Example 5

[0152] Weigh 250 g of the distilled light-phase oil B1-3 in Example 3 and add it to a 500-ml three-necked flask. Then add 7.5 g of immobilized DF Amano 15 enzyme and react at 60 °C for 4 hours. Filter to remove the immobilized DF Amano 15 enzyme, and centrifuge to remove glycerol to obtain the reaction oil D2-5. Subject the reaction oil D2-5 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain the distilled light-phase oil E2-5 and the distilled heavy-phase diglyceride oil F2-5. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of the oil F2-5 are shown in Table 1.

[0153] Comparative Example 6

[0154] Weigh 250 g of the distilled light-phase oil B2-1 (acid value 5.42 mg KOH / g) in Comparative Example 1 and add it to a 500-ml three-necked flask. Then add 7.5 g of immobilized DF Amano 15 enzyme and react at 60 °C for 4 hours. Filter to remove the immobilized DF Amano 15 enzyme, and centrifuge to remove glycerol to obtain the reaction oil D2-6. Subject the reaction oil D2-6 to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain the distilled light-phase oil E2-6 and the distilled heavy-phase diglyceride oil F2-6. The diglyceride content, 1,3-diglyceride content, and 1,3-diglyceride percentage of the oil F2-6 are shown in Table 1.

[0155] Comparative Example 7

[0156] Weigh 250 g of the distilled light-phase oil B2-1 (acid value 5.42 mg KOH / g) in Comparative Example 1 and add it to a 500-ml three-necked flask. Then add 7.5 g of Novozym TL IM enzyme and react at 60 °C for 4 hours. Filter to remove the Novozym TL IM enzyme, and centrifuge to remove glycerol to obtain the reaction oil D2-7. Subject the reaction oil D2-7 to molecular distillation at a vacuum of 1.0×10 -3At mbar, molecular distillation was carried out at a distillation temperature of 175 °C to obtain distillate light-phase oil E2-7 and distillate heavy-phase diglyceride oil F2-7. The diglyceride content, 1,3-diglyceride content and percentage of 1,3-diglyceride in oil F2-7 are shown in Table 1.

[0157] Comparative Example 8

[0158] Weigh 140 g of the distillate light-phase oil B1-1 in Example 1 into a 500 ml three-necked flask, add 110 g of oleic acid and mix evenly to obtain oil B2-8. The acid value of oil B2-8 was measured to be 91.16 mg KOH / g. Add 7.5 g of Novozym 435 enzyme and react at a temperature of 60 °C and a vacuum of 6 mbar for 4 hours. Filter to remove Novozym 435 enzyme to obtain reaction oil D2-8. The reaction oil D2-8 was subjected to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 175 °C to obtain distillate light-phase oil E2-8 and distillate heavy-phase diglyceride oil F2-8. The diglyceride content, 1,3-diglyceride content and percentage of 1,3-diglyceride in oil F2-8 are shown in Table 1.

[0159] Comparative Example 9

[0160] Weigh 250 g of the distillate light-phase oil E1-10 (acid value 7.48 mg KOH / g) in Example 10 into a 500 ml three-necked flask. Add 7.5 g of Novozym 435 enzyme and react at a temperature of 55 °C for 3.5 hours. Filter to remove Novozym 435 enzyme and centrifuge to remove glycerol to obtain reaction oil D2-9. The reaction oil D2-9 was subjected to molecular distillation at a vacuum of 1.0×10 -3 mbar and a distillation temperature of 170 °C to obtain distillate light-phase oil E2-9 and distillate heavy-phase diglyceride oil F2-9. The diglyceride content, 1,3-diglyceride content and percentage of 1,3-diglyceride in oil F2-9 are shown in Table 1.

[0161] Table 1 Raw materials and results of examples and comparative examples

[0162]

[0163]

[0164] As can be seen from Table 1, the content of diglycerides prepared in Examples 1 to 11 is all above 65%, the content of 1,3-diglycerides is greater than 50%, and the percentage of 1,3-diglycerides in the obtained diglycerides reaches more than 80%; while the content of diglycerides prepared in Comparative Examples 1 to 8 is less than 50%, the content of 1,3-diglycerides is less than 35%, and the percentage of 1,3-diglycerides is less than 65%. It shows that limiting the acid value of the oil to less than 2 mg KOH / g can effectively increase the yield of diglycerides, especially the yield of 1,3-diglycerides.

[0165] Comparing Examples 10-11 with Comparative Example 9, it can be seen that by recycling the distilled heavy-phase oil C in Step 2 and the distilled light-phase oil E with an acid value less than 2 mg KOH / g in Step 4, the diglyceride content in the obtained oil F is all above 65%, the content of 1,3-diglycerides is greater than 50%, and the percentage of 1,3-diglycerides is above 80%; it shows that when using the method of the present invention to prepare diglyceride oil, the materials can be recycled and reused without by-products, which is economical and environmentally friendly.

[0166] According to the conventional transesterification method in the prior art to prepare diglycerides, fatty acids need to be added additionally during the reaction, and an organic solvent system is used. It can be seen from Comparative Example 8 that glycerol monoster and oleic acid are subjected to transesterification reaction under vacuum in a reaction system without using an organic solvent, and the diglyceride content and the proportion of 1,3-diglycerides in the obtained product are much lower than those in the examples. Therefore, the method of the present application can increase the yield of diglycerides, especially 1,3-diglycerides, without using an organic solvent and without adding additional fatty acids, which is more environmentally friendly and safe than the prior art and saves costs.

Claims

1. A method for preparing diglyceride oil, characterized in that, It includes the following steps: React oil B under the action of an enzyme to obtain reaction oil D; Perform molecular distillation on the reaction oil D to obtain heavy-phase oil F; Among them, the components of the oil B include monoglyceride, and the acid value is less than 2 mg KOH / g; the oil F is diglyceride.

2. The preparation method according to claim 1, characterized in that, The preparation method further includes the following steps: Perform glycerolysis on oil and glycerol to obtain reaction oil A; Perform molecular distillation on the reaction oil A to obtain light-phase oil B; Among them, the oil B includes the light-phase oil B.

3. The preparation method according to claim 2, characterized in that, The glycerolysis reaction includes chemical glycerolysis, and the catalyst used in the chemical glycerolysis includes at least one of the following: NaOH, KOH, Ca(OH)2, sodium stearate, calcium stearate.

4. The preparation method according to claim 2, characterized in that, The chemical glycerolysis reacts for 3.5 - 6 h under vacuum or inert gas protection; the reaction temperature is 180°C to 230°C.

5. The preparation method according to claim 2, characterized in that, The preparation method of the diglyceride further includes the following steps: Perform molecular distillation on the reaction oil A to obtain light-phase oil B and heavy-phase oil C; Add glycerol to the heavy-phase oil C for glycerolysis reaction to obtain reaction oil A; and / or The preparation method of the diglyceride further includes the following steps: Perform molecular distillation on the reaction oil D to obtain light-phase oil E and heavy-phase oil F; React the light-phase oil E under the action of an enzyme to obtain reaction oil D.

6. The preparation method according to claim 1 or 2, characterized in that, The temperature of the molecular distillation is 140 to 180 °C; the vacuum degree is 1.0×10 -2 ~1.0×10 -3 mbar; preferably, the light-phase oil B obtained by the molecular distillation comprises two steps of molecular distillation; more preferably, the two steps of molecular distillation include: first, molecular distillation is used to remove fatty acids and excess glycerol, and then molecular distillation is carried out to obtain the light-phase oil B.

7. The preparation method according to claim 2, characterized in that, The oil for the glycerolysis reaction is vegetable oil; preferably, the vegetable oil includes at least one of soybean oil, sunflower oil, olive oil, palm oil, and corn oil.

8. The preparation method according to claim 1 or 5, characterized in that, The enzyme is lipase; preferably, the lipase is immobilized Candida antarctica lipase B.

9. The preparation method according to claim 8, characterized in that, The addition amount of the enzyme is 1 - 6 wt%; preferably, the reaction temperature of the enzyme is 50°C to 70°C, and the reaction time is 1 - 4 hours.

10. The diglyceride prepared by the preparation method according to any one of claims 1-9, characterized in that, The content of 1,3-diglyceride in the diglyceride accounts for more than 80 wt% of the total amount.

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