Method for rapidly preparing high-purity diglyceride corn oil based on electrochemical reduction reaction

Abstract

The invention belongs to the field of functional grease preparation, and particularly relates to a method for rapidly preparing high-purity diglyceride (DAG) corn oil based on an electrochemical reduction reaction. The method is realized by the following steps: firstly, mixing electrolyte, corn oil and glycerol, and carrying out electrochemical reaction; and separating and purifying the product. By controlling reaction raw materials, reaction parameters and separation conditions, high-purity DAG (more than 90%, in which the content of 1, 3-DAG reaches more than 70%) can be obtained, and the content of byproducts such as 1, 2-DAG and free fatty acid is low, so that the market competitiveness of the product can be improved. The prepared high-purity DAG corn oil has potential health benefits, is suitable for being applied to functional food, health care products and medical products, and plays an important role in controlling blood fat, preventing cardiovascular diseases and the like.

Description

Technical Field

[0001] The invention belongs to the field of functional oil preparation, and specifically relates to a method for rapidly preparing high-purity diacylglycerol (DAG) corn oil based on an electrochemical reduction reaction. Background Art

[0002] Diacylglycerol (DAG), as an important functional lipid, has a wide range of applications in food, cosmetics and medicine, especially in regulating blood lipids and controlling weight, and has received widespread attention.

[0003] Existing methods for preparing DAG include chemical synthesis and enzymatic synthesis. The reaction conditions of chemical methods are harsh and the environmental pollution is serious, so the existing DAG synthesis is mainly based on enzymatic synthesis. However, the cost of enzymatic synthesis is high, the cycle is long, and it is difficult to achieve the selective preparation of DAG. For example, patents (CN202411312663.7, CN202411133883.3) disclose a two-step method for preparing DAG. Although it has a high DAG content, the preparation time is long and the steps are cumbersome. Patents (CN202411168456.9, CN202410998442.3, CN202410948553.3) and others all disclose methods for preparing DAG products using enzymatic methods, but none of them solve the problem of long DAG preparation time and many by-products. Therefore, how to quickly prepare high-purity DAG under mild and environmentally friendly conditions has become an important problem in this field. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for rapidly preparing high-purity diacylglycerol (DAG) corn oil based on electrochemical reduction reaction. The method can efficiently generate a specific compound diacylglycerol through electrochemical reduction reaction under mild conditions. And by controlling parameters such as electrode materials, potential, current density, etc., the target product can be selectively generated and the occurrence of side reactions can be reduced. The reaction time is short, the energy consumption is low, it is green and environmentally friendly, and the product purity is high.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: The present invention provides a method for rapidly preparing high-purity diglyceride corn oil, comprising the following steps: (1) adding electrolyte and a mixture of corn oil and glycerol to an electrolytic cell, then adding lipase and gallic acid to the electrolytic cell, and slowly dropping a saturated sodium bicarbonate solution under stirring to carry out an electrochemical reaction; (2) Product separation and purification: After the reaction is completed, the oil and water are separated by centrifugation, the oil phase is taken, DAG is extracted with an organic solvent, and DAG is eluted and purified using a silver ion-modified silica gel column.

[0006] Furthermore, in step (1), the volume ratio of the electrolyte to the mixture is 1:4-6; the amount of the lipase added is 1%-2% of the mass of the mixture; the amount of the gallic acid added is 0.2%-0.3% of the mass of the mixture; and the amount of the saturated sodium bicarbonate solution added is 0.2%-0.3% of the mass of the mixture.

[0007] Furthermore, in step (1), the electrolyte is 0.1 M potassium phosphate (K2HPO4) or sodium sulfate (Na2SO4); and the volume ratio of corn oil to glycerol is 3-4:1.

[0008] Furthermore, in step (1), the conditions of the electrochemical reaction are as follows: the electrode material is a carbon-based material (such as carbon black activated carbon) as the anode, and a graphite or platinum electrode is used as the cathode; the electrochemical reaction device is: the reactor is a single-chamber electrolytic cell, the anode and the cathode are both immersed in the electrolyte solution, and Ag / AgCl is used as the reference electrode.

[0009] Furthermore, in step (1), the reaction temperature of the electrochemical reaction is 25-50 °C and the current density is controlled at 10-20 mA / cm 2 The potential was set at −0.6 to −1.0 V (relative to the Ag / AgCl reference electrode) and the reaction was carried out for 1.5–2 h.

[0010] Furthermore, in step (2), the centrifugation is carried out at 4500-5000 rpm for 30 min.

[0011] Furthermore, in step (2), the organic solvent is hexane or dichloromethane; and the elution adopts a hexane-ethyl acetate system with a volume ratio of 3:1.

[0012] The beneficial effects of the present invention are: (1) High selectivity: DAG is selectively prepared through electrochemical reduction technology. Compared with traditional chemical methods, this method does not require harsh reaction conditions and has fewer by-products, which is conducive to the separation and purification of products.

[0013] (2) Green and environmentally friendly: The electrochemical method can be carried out at room temperature and pressure, avoiding the large amount of organic solvents and catalysts used in chemical synthesis, reducing the risk of environmental pollution, and meeting the requirements of green chemical industry.

[0014] (3) High efficiency and energy saving: Compared with the enzymatic method, electrochemical synthesis has obvious advantages in cost and reaction rate. By optimizing electrode materials and reaction conditions, this method can achieve high yields at low energy consumption and is suitable for industrial scale-up production.

[0015] (4) High purity: By controlling the reaction raw materials, reaction parameters and separation conditions, high-purity DAG (more than 90%, of which the 1,3-DAG content reaches more than 70%) can be obtained, and the content of by-products such as 1,2-DAG and free fatty acids is low, which is conducive to improving the market competitiveness of the product.

[0016] (5) Broad prospects: The high-purity DAG corn oil prepared by the present invention has potential health benefits and is suitable for application in functional foods, health products and pharmaceutical products. It plays an important role in controlling blood lipids and preventing cardiovascular diseases. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0018] Example 1 1. Raw material preparation: corn oil, glycerol, and lipase are used as reaction raw materials. The electrolyte solution is 0.1 M potassium phosphate (K2HPO4). The electrode material is carbon black as the anode and platinum electrode as the cathode.

[0019] 2. Electrochemical reaction device: The reactor uses a single-chamber electrolytic cell, the anode and cathode are immersed in the electrolyte solution, and Ag / AgCl is used as the reference electrode.

[0020] 3. Reaction conditions setting: Temperature control: The reaction temperature was set at 30 °C to maintain mild reaction conditions and avoid the occurrence of side reactions.

[0021] Current density: Control the current density at 10-20 mA / cm 2 to ensure the reaction rate and selectivity of DAG generation.

[0022] Potential control: The potential was set to −0.6 to −1.0 V (vs. Ag / AgCl reference electrode) for electrochemical reduction reactions.

[0023] 4. Electrochemical reduction reaction step: add 1 / 5 of the volume of electrolyte to the electrolytic cell, add a mixture of corn oil and glycerol to a volume of 4 / 5 of the volume of the electrolytic cell, wherein the ratio of corn oil to glycerol is 3:1, then add lipase accounting for 2% of the mass of the mixture and gallic acid accounting for 0.2% of the mass of the mixture to the electrolytic cell, start the electrochemical reaction device and stirring device (180 rpm), and slowly drop a saturated sodium bicarbonate solution accounting for 0.3% of the mass of the mixture during stirring. Apply the set current density and potential, and control the reaction time to 2 hours.

[0024] 5. Product separation and purification: After the reaction is completed, centrifuge at 4500-5000 rpm for 30 min to separate oil and water, take the oil phase, extract DAG with an organic solvent (such as hexane or dichloromethane), and purify it using a silver ion modified silica gel column and elute (hexane-ethyl acetate system, volume ratio 3:1) to separate DAG from other by-products.

[0025] Comparative Example 1 Steps 1-3 are the same as in Example 1; 4. Electrochemical reduction reaction step: add 1 / 5 of the volume of electrolyte to the electrolytic cell, add a mixture of corn oil and glycerol to a volume of 4 / 5 of the volume of the electrolytic cell, wherein the ratio of corn oil to glycerol is 3:1, then add lipase accounting for 2% of the mass of the mixture to the electrolytic cell, start the electrochemical reaction device and the stirring device (180rpm), and slowly drop a saturated sodium bicarbonate solution accounting for 0.3% of the mass of the mixture during the stirring process. Apply the set current density and potential, and control the reaction time to 2 hours.

[0026] 5. Product separation and purification: After the reaction is completed, centrifuge at 4500-5000 rpm for 30 min to separate oil and water, take the oil phase, extract DAG with an organic solvent (such as hexane or dichloromethane), and purify it using a silver ion modified silica gel column and elute (hexane-ethyl acetate system, volume ratio 3:1) to separate DAG from other by-products.

[0027] Effect Example The methods provided in Example 1 and Comparative Example 1 were used to detect the relevant contents; DAG content determination: GB / T26636-2011; Free fatty acids: NY / T 1797 1,3-DAG and 1,2-DAG content: self-established method, as follows: 1. Instruments and Equipment 1. Electronic balance: Measuring range: 0-200g; Accuracy: 0.0001g; Status: within the calibration validity period.

[0028] 2. n-Hexane, chromatographic grade; 3. Isopropanol, chromatographic grade; 4. Formic acid, chromatographic grade.

[0029] 5. Triglyceride standard: content ≥95.0%, or certified standard solution.

[0030] 6.1,3-Diglyceride standard: content ≥95.0%, or certified standard solution.

[0031] 7.1,2-Diglyceride standard: content ≥95.0%, or certified standard solution.

[0032] 8. Monoglyceride standard: content>95.0%, or certified standard solution.

[0033] 9. High performance liquid chromatograph: with differential detector.

[0034] 10. Disposable microporous filter head: with 0.22 μm microporous filter membrane; 2. Testing conditions 1. Chromatographic column: C18 (250 mm × 4.6 mm × 5 μm) 2. Flow rate: 1.0 mL / min; 3. Column temperature: 35 ℃; 4. Injection volume: 10 μL 3. Running time: 30min 4. Mobile phase: n-hexane + isopropanol + formic acid = 20 + 1 + 0.003 (volume fraction) 3. Qualitative analysis of standard solutions Inject the standard series working solutions into the liquid chromatograph respectively to obtain the corresponding peaks corresponding to the corresponding elution times.

[0035] 4. Sample determination Weigh 0.3 g (accurate to 0.001 g) of the sample into a 10 mL volumetric flask, dissolve it in n-hexane-isopropanol solution (19:1), mix it thoroughly, and make up to the mark. After mixing thoroughly, filter it through a 0.22 μm filter membrane and analyze it by high performance liquid chromatography.

[0036] 5. Calculation of results Area normalization method.

[0037] The specific results are shown in Table 1.

[0038] Table 1

Claims

1. A method for rapidly preparing high-purity diglyceride corn oil, characterized in that: The following steps are involved: (1) adding electrolyte and a mixture of corn oil and glycerol to an electrolytic cell, then adding lipase and gallic acid to the electrolytic cell, and slowly dropping a saturated sodium bicarbonate solution under stirring to carry out an electrochemical reaction; (2) Product separation and purification: After the reaction is completed, the oil and water are separated by centrifugation, the oil phase is taken, DAG is extracted with an organic solvent, and DAG is eluted and purified using a silver ion-modified silica gel column.

2. The method according to claim 1, characterized in that In step (1), the volume ratio of the electrolyte to the mixture is 1:4-6; the amount of the lipase added is 1%-2% of the mass of the mixture; the amount of the gallic acid added is 0.2%-0.3% of the mass of the mixture; and the amount of the saturated sodium bicarbonate solution added is 0.2%-0.3% of the mass of the mixture.

3. The method according to claim 1 or 2, characterized in that: In step (1), the electrolyte is 0.1 M potassium phosphate or sodium sulfate; and the volume ratio of corn oil to glycerol is 3-4:

1.

4. The method according to any one of claims 1 to 3, characterized in that: In step (1), the conditions of the electrochemical reaction are: the electrode material selects a carbon-based material as the anode, and a graphite or platinum electrode as the cathode; the electrochemical reaction device: the reactor selects a single-chamber electrolytic cell, the anode and the cathode are both immersed in the electrolyte solution, and Ag / AgCl is used as the reference electrode.

5. The method according to claim 4, characterized in that In step (1), the reaction temperature of the electrochemical reaction is 25-50 °C and the current density is controlled at 10-20 mA / cm 2 The potential was set at −0.6 to −1.0 V (relative to the Ag / AgCl reference electrode) and the reaction was carried out for 1.5–2 h.

6. The method according to claim 1, characterized in that In step (2), the centrifugation is carried out at 4500-5000 rpm for 30 min.

7. The method according to claim 1 or 6, characterized in that: In step (2), the organic solvent is hexane or dichloromethane; and the elution adopts a hexane-ethyl acetate system with a volume ratio of 3:1.

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