A self-emulsifying vegetable fermented oil and a preparation method thereof

Abstract

The application provides a self-emulsifying plant fermentation oil and a preparation method thereof, and comprises the following steps: mixing plant oil with water, adding biological enzymes, performing enzymolysis, and then performing enzyme inactivation to obtain an enzymolysis product; wherein the biological enzymes are 1,3-specific lipase; adding phospholipids to the obtained enzymolysis product, performing high-pressure homogenization to obtain a homogenized liquid; adding fermentation bacteria to the obtained homogenized liquid, performing fermentation, sterilization and separation to obtain the self-emulsifying plant fermentation oil. The self-emulsifying plant fermentation oil obtained by the preparation method has good compatibility with a water-based system, and has good emulsification stability and storage stability.

Description

Technical Field

[0001] This invention relates to the field of agricultural technology, and in particular to a self-emulsifying plant fermentation oil and its preparation method. Background Technology

[0002] In recent years, plant oils have been increasingly used in cosmetics and personal care products. Natural plant oils are mainly composed of triglyceride esters, with different fatty acids of 14-22 carbon chains linked to the sn-1, sn-2, and sn-3 positions of their glycerol backbone, forming structurally diverse complex triglycerides. When using plant oils as a base material or additive in cosmetics and personal care products, microbial fermentation technology is often used to transform them into smaller molecules that are easily absorbed by the skin in order to achieve more effective skin protection.

[0003] Fermented vegetable oils are rich in antioxidants, but they have a high content of unsaturated fatty acids, making them susceptible to oxidation reactions caused by various external factors such as oxygen, light, high temperature, and moisture. This leads to oxidation and deterioration of the oil, degradation or inactivation of active ingredients, and poor long-term stability.

[0004] In addition, due to the strong hydrophobicity of plant oils, they have poor compatibility with water-based cosmetics and personal care products, requiring the addition of a large amount of surfactants for dispersion. This not only easily leads to phenomena such as demulsification and layering, but also easily causes sticky skin after use. Summary of the Invention

[0005] The purpose of this invention is to provide a self-emulsifying plant fermented oil and its preparation method, so as to solve the problems of poor compatibility and poor stability of plant fermented oil with water-based systems in the prior art.

[0006] This invention provides the following technical solution: A method for preparing a self-emulsifying fermented vegetable oil includes the following steps: (1) After mixing vegetable oil with water, add biological enzyme, perform enzymatic hydrolysis and enzyme inactivation to obtain enzymatic hydrolysis product; wherein, the biological enzyme is a 1,3 position specific lipase; (2) Add phospholipids to the enzymatic hydrolysis product obtained in step (1), homogenize under high pressure to obtain a homogenized liquid; (3) Add fermentation bacteria to the homogenized liquid obtained in step (2), and carry out fermentation, sterilization and separation to obtain the self-emulsifying plant fermented oil.

[0007] Lipases can enzymatically hydrolyze triglycerides into glycerol and fatty acids. In this invention, a 1,3-position specific lipase is used to pre-cleave vegetable oils, which can selectively hydrolyze the 1,3-position ester bonds of triglycerides, so that the enzymatic hydrolysis products are mainly 2-monoglycerides (2-monoglycerides mentioned below in this invention are all referred to as monoglycerides) and some glycerol and fatty acids. The monoglyceride molecule has a lipophilic long-chain alkyl group and two hydrophilic hydroxyl groups, with the two hydroxyl groups located at both ends of the molecule and the long-chain alkyl group located in the middle of the molecule. Its molecular configuration is conducive to the hydrophilic group extending into the aqueous phase and the hydrophobic group extending into the oil phase, resulting in strong interfacial adsorption capacity and good surface activity.

[0008] After enzymatic hydrolysis and enzyme inactivation, vegetable oil contains monoglycerides in the hydrolysis products, but the vegetable oil still exists in the form of large oil particles. This invention uses high-pressure homogenization to shear and impact the larger oil droplets in the hydrolysis products into nano-sized oil droplets with a uniform particle size distribution of 100-500 nm, significantly increasing the specific surface area. This allows phospholipid molecules and monoglyceride molecules to be better adsorbed onto the surface of the oil droplets, forming water-in-oil microemulsion particles. In some embodiments, in step (2), the high-pressure homogenization conditions are 40-45℃, 100-120 MPa, and 2-3 cycles. The oil droplet size decreases with increasing pressure, but excessive pressure may lead to localized overheating, membrane damage, and oil droplet re-fusion.

[0009] In some embodiments, in step (2), the phospholipid is selected from one or more of soybean phospholipid, egg yolk lecithin, and hydrogenated lecithin; optionally, the phospholipid is soybean phospholipid, and the weight ratio of the enzymatic hydrolysis product to the soybean phospholipid is (6-8):1. Phospholipid molecules (e.g., soybean phospholipid) have two lipophilic long-chain alkyl groups and a hydrophilic phosphate group as well as choline / inositol groups. During high-pressure homogenization, phospholipids and monoglycerides produced by enzymatic hydrolysis spontaneously and directionally arrange themselves on the surface of oil droplets. The hydrophilic head groups of phospholipid molecules are relatively large, occupying a large area at the interface and forming a relatively "loose" arrangement. Monoglyceride molecules have relatively small hydrophilic head groups. Combined with their unique molecular configuration, they can better insert between phospholipid molecules, filling the gaps between the hydrophobic chains of phospholipid molecules, thereby increasing the interfacial packing density. Furthermore, the hydrophilic groups of phospholipid molecules can combine with the hydrophilic groups of monoglyceride molecules through hydrogen bonds and electrostatic interactions, further enhancing the membrane stability.

[0010] In some embodiments, in step (1), the vegetable oil is camellia seed oil or olive oil; preferably, the vegetable oil is camellia seed oil. Optionally, the weight ratio of the vegetable oil to the water is 1:(2-5).

[0011] In some embodiments, in step (1), the 1,3-position specific lipase is selected from either *Rhizopus micranthum* lipase or *Candida antarcticis* lipase B; optionally, the weight ratio of the vegetable oil to the 1,3-position specific lipase is (10-100):1. In some embodiments, the enzymatic hydrolysis conditions are: at a temperature of 35-45°C and a pH of 7-8, hydrolysis is carried out for 2-4 hours. Optionally, the hydrolysis endpoint is that the weight percentage of monoglycerides in the hydrolysis product is 2%-3.5%. In this invention, the monoglyceride content during the hydrolysis process can be detected using HPLC-ELSD to monitor the progress of the hydrolysis reaction and to inactivate the enzyme when the monoglyceride content reaches the target value. Both *Rhizopus micranthum* lipase and *Candida antarcticis* lipase B are commercially available.

[0012] In some embodiments, in step (3), the fermenting bacteria are a compound bacterial agent, including any one of Lactobacillus plantarum, Saccharomyces cerevisiae, Bifidobacterium, and Yersinia lipolytica. Yersinia lipolytica secretes lipase to hydrolyze triglycerides and directionally generate monoglycerides. The assembly of the monoglyceride-phospholipid composite membrane is a dynamic equilibrium process. Monoglyceride molecules insert into the gaps between phospholipid molecules to increase the interfacial packing density and enhance membrane stability. If monoglycerides are added all at once, monoglyceride molecules and phospholipid molecules will compete for binding sites, which can easily lead to local aggregation or defective structures. This invention allows monoglycerides to participate in the formation of the composite membrane in two stages, which enables monoglyceride molecules and phospholipid molecules to arrange in an orderly manner and form a more stable composite membrane structure. During fermentation, Lactobacillus plantarum, Saccharomyces cerevisiae, and Bifidobacterium can decompose macromolecules to obtain small molecule metabolites, making the molecular weight of oils smaller, easier to emulsify and absorb, and producing a variety of bioactive substances and antioxidant components. This invention utilizes a compound microbial agent to ferment the product after high-pressure homogenization, which can further improve the self-emulsifying and antioxidant capabilities of fermented vegetable oils, and further enhance membrane structure stability. Specifically, the preservation numbers for *Lactobacillus plantarum* (SHMCC D24748), *Saccharomyces cerevisiae* (CICC 1002), *Bifidobacterium* (CGMCC NO.18094), and *Yarrowia lipolyticis* (ATCC 90811) are listed.

[0013] Optionally, the fermentation bacteria consist of *Lactobacillus plantarum* and *Yersinia lipolytica*; optionally, the inoculum ratio of *Lactobacillus plantarum* to *Yersinia lipolytica* is (2-4):1; optionally, the fermentation is carried out at a total inoculum of 3-8% for 8-12 hours at a temperature of 28-35℃ and a pH of 5.5-6.5.

[0014] In some embodiments, step (3) further includes the step of adding chitosan and sodium tripolyphosphate: fermentation bacteria are added to the homogeneous liquid obtained in step (2), and fermentation, sterilization, and separation are carried out to obtain an oily liquid. Chitosan, sodium tripolyphosphate, citric acid, and water are added to the oily liquid and mixed evenly to obtain a self-emulsifying plant fermented oil encapsulated in a carrier. In this invention, the chitosan can be first dissolved in an aqueous citric acid solution (adjusting the pH value to 4-6), and the sodium tripolyphosphate can be first dissolved in water, and then added to the oily liquid and mixed evenly.

[0015] Optionally, the weight ratio of the oily liquid, chitosan, sodium tripolyphosphate, and water is (30-40):(1-2):(0.1-1):(250-500).

[0016] When the citric acid aqueous solution of chitosan is mixed with the oily liquid, chitosan molecules migrate from the aqueous phase to the oil-water interface and electrostatically bind with phospholipid molecules adsorbed on the surface of oil droplets through amino-phosphate groups, forming a "phospholipid-chitosan" bilayer structure. The chitosan molecular chains extend in the aqueous phase, forming a spatial barrier that prevents oil droplets from approaching each other, which helps to improve the stability of self-emulsifying fermented vegetable oil. At the same time, the hydroxyl and amino groups on the chitosan molecular chains form a ternary hydrogen bond network with the hydroxyl and carboxyl groups of phospholipids and monoglycerides, which helps to improve the stability of the membrane structure. In addition, as a polysaccharide, chitosan can give self-emulsifying fermented vegetable oil better hydrophilicity.

[0017] Metal ions generate reactive oxygen species such as hydroxyl radicals and superoxide anions through the Fenton reaction, attacking the double bonds of unsaturated fatty acids in vegetable oils and initiating a chain oxidation reaction. Sodium tripolyphosphate molecules contain five dissociable phosphate oxygen ions, forming a polydentate coordination structure that can form stable water-soluble chelates with metal ions, thereby rendering the metal ions inactive and unable to trigger the Fenton reaction, thus blocking the lipid oxidation chain reaction at its source. Adding sodium tripolyphosphate to fermented vegetable oils significantly enhances their antioxidant capacity and inhibits the oxidation of fermented vegetable oils. Simultaneously, sodium tripolyphosphate can form ionic cross-linking points with chitosan through electrostatic attraction, causing chitosan molecular chains to approach and cross-link, forming a three-dimensional network structure, further improving membrane stability and allowing fermented vegetable oils to be more stably encapsulated within the composite membrane. The CAS number of the chitosan is 9012-76-4, and the CAS number of the sodium tripolyphosphate is 7758-29-4.

[0018] This invention also provides a self-emulsifying plant fermented oil, obtained by the above-described method for preparing self-emulsifying plant fermented oil. The plant fermented oil obtained by the method described in this invention can achieve self-emulsification simply by adding an aqueous phase, exhibiting good compatibility with water-based systems, eliminating the need for additional emulsifiers, and effectively reducing the use of emulsifiers.

[0019] The above-described solution of the present invention has at least the following beneficial effects: The method for preparing self-emulsifying plant fermented oil according to the present invention involves encapsulating the plant fermented oil in a monoglyceride-phospholipid composite membrane, and incorporating the monoglyceride into the formation of the composite membrane in two stages: enzymatic hydrolysis and fermentation. Furthermore, the surface of the monoglyceride-phospholipid composite membrane is coated with an ionic crosslinking network structure of chitosan-sodium tripolyphosphate, thereby giving the prepared plant fermented oil a good self-emulsifying effect and good emulsification stability and storage stability. Detailed Implementation

[0020] Unless otherwise specified in the embodiments of this invention, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products; different manufacturers and models of raw materials do not affect the implementation of the technical solution or the achievement of the technical effect of this invention.

[0021] The content of monoglycerides in the enzymatic hydrolysis products was determined by HPLC-ELS: Monoglyceride standards were dissolved in isopropanol to prepare a standard solution. The sample to be tested and the reference standard were injected separately into the HPLC-ELSD instrument for liquid chromatography detection. The chromatographic column was C18 (250 mm x 4.6 mm, 5 μm), the column temperature was 30℃, mobile phase A was acetonitrile-isopropanol, mobile phase B was n-hexane-isopropanol, and the flow rate was 1 mL / min. The sample components were qualitatively identified using the standards, and the sample concentration showed a linear relationship with the peak area.

[0022] Example 1 The method for preparing self-emulsifying fermented vegetable oil in this embodiment includes the following steps: (1) Camellia seed oil and water were mixed at a weight ratio of 1:4 and then Rhizopus milchiculatus lipase (purchased from Beijing Gaoruisen Technology Co., Ltd., the same below) was added. The mixture was hydrolyzed at a temperature of 40℃ and a pH of 8.0 for 4 hours. After enzyme inactivation, the hydrolysate was obtained. The weight percentage of monoglyceride in the hydrolysate was 3.5%. The weight ratio of the camellia seed oil to the Rhizopus miltiorrhizos lipase is 10:1. (2) Add soybean lecithin (soybean lecithin purchased from Tianjin Hexiyuan Phospholipid Technology Co., Ltd., the same below) to the enzymatic hydrolysis product obtained in step (1), transfer it to a high-pressure homogenizer, 40℃, 100Mpa, circulate twice to obtain a homogenized liquid; wherein, the amount of soybean lecithin added is: the weight ratio of soybean lecithin to the enzymatic hydrolysis product is 1:6; (3) Under aseptic conditions, the homogenized liquid obtained in step (2) is added to the fermentation tank, and Lactobacillus plantarum is inoculated into the fermentation tank at a total inoculation amount of 6%. The fermentation is carried out at a temperature of 35°C and a pH of 6.5 for 8 hours. After sterilization and separation, the oil phase is taken as the self-emulsifying plant fermented oil. In this embodiment, the total inoculation volume refers to the percentage of the volume of the inoculated microorganisms relative to the total volume of the fermentation substrate (the same applies below, and will not be repeated hereafter).

[0023] Example 2 The method for preparing self-emulsifying fermented vegetable oil in this embodiment includes the following steps: (1) Camellia seed oil and water were mixed at a weight ratio of 1:4 and then Rhizopus milchii lipase was added. The mixture was hydrolyzed at 40°C and pH 7.5 for 3 hours. After enzyme inactivation, the hydrolysate was obtained. The weight percentage of monoglyceride in the hydrolysate was 2.5%. The weight ratio of the camellia seed oil to the Rhizopus miltiorrhizos lipase is 10:1. (2) Add soybean lecithin to the enzymatic hydrolysis product obtained in step (1), transfer it to a high-pressure homogenizer, and cycle it twice at 40°C and 110 MPa to obtain a homogenized liquid; wherein the amount of soybean lecithin added is: the weight ratio of soybean lecithin to the enzymatic hydrolysis product is 1:7. (3) Under sterile conditions, the homogenized liquid obtained in step (2) is added to the fermentation tank, and Lactobacillus plantarum and Yeast lipolytica are inoculated into the fermentation tank at a total inoculation amount of 8%. The fermentation is carried out at a temperature of 30°C and a pH of 6.5 for 10 hours. The mixture is then sterilized and separated. The oil phase after separation is the self-emulsifying plant fermented oil. The inoculation ratio of Lactobacillus plantarum to Yersinia lipolytica was 3:1.

[0024] Example 3 The method for preparing self-emulsifying fermented vegetable oil in this embodiment includes the following steps: (1) Camellia seed oil and water were mixed at a weight ratio of 1:3 and then Rhizopus milchii lipase was added. The mixture was hydrolyzed at 45°C and pH 8.0 for 2 hours. After enzyme inactivation, the hydrolysate was obtained. The weight percentage of monoglycerides in the hydrolysate was 3.0%. The weight ratio of the camellia seed oil to the Rhizopus miltiorrhizos lipase is 20:1. (2) Add soybean lecithin to the enzymatic hydrolysis product obtained in step (1), transfer it to a high-pressure homogenizer, and cycle it 3 times at 45°C and 100 MPa to obtain a homogenized liquid; wherein the amount of soybean lecithin added is: the weight ratio of soybean lecithin to the enzymatic hydrolysis product is 1:6. (3) Under sterile conditions, the homogenized liquid obtained in step (2) is added to the fermentation tank, and Saccharomyces cerevisiae and Yeast lipolytica are inoculated into the fermentation tank at a total inoculation amount of 6%. The fermentation is carried out at a temperature of 28°C and a pH of 5.5 for 12 hours. The mixture is then sterilized and separated. The oil phase after separation is the self-emulsifying plant fermented oil. The inoculation ratio of Saccharomyces cerevisiae to Yersinia lipolytica was 2:1.

[0025] Example 4 The method for preparing self-emulsifying fermented vegetable oil in this embodiment includes the following steps: (1) Camellia seed oil and water were mixed at a weight ratio of 1:5 and Candida antarctica lipase B (purchased from Beijing Gaoruisen Technology Co., Ltd., the same below) was added. The mixture was hydrolyzed for 3 hours at a temperature of 37℃ and a pH of 7.0. After enzyme inactivation, the hydrolysate was obtained. The weight percentage of monoglyceride in the hydrolysate was 2.0%. The weight ratio of the camellia seed oil to the Candida antarcticis lipase B is 25:2. (2) Add soybean lecithin to the enzymatic hydrolysis product obtained in step (1), transfer it to a high-pressure homogenizer, 40°C, 120 MPa, and cycle twice to obtain a homogenized liquid; wherein, the amount of soybean lecithin added is: the weight ratio of soybean lecithin to the enzymatic hydrolysis product is 1:8; (3) Under sterile conditions, the homogenized liquid obtained in step (2) is added to the fermentation tank, and Lactobacillus plantarum and Yeast lipolytica are inoculated into the fermentation tank at a total inoculation amount of 5%. The fermentation is carried out at a temperature of 30°C and a pH of 6.5 for 10 hours. The mixture is then sterilized and separated. The oil phase after separation is the self-emulsifying plant fermented oil. The inoculation ratio of Lactobacillus plantarum to Yersinia lipolytica was 4:1.

[0026] Example 5 The preparation method of Example 5 is the same as that of Example 2, except that in step (1), camellia seed oil and water are mixed at a weight ratio of 1:4 and then Rhizopus milchii lipase is added. The mixture is hydrolyzed at 40°C and pH 7.5 for 1 hour. After enzyme inactivation, the hydrolysate is obtained. The weight percentage of monoglyceride in the hydrolysate is 1.2%. The weight ratio of the camellia seed oil to the *Rhizopus micranthum* lipase is 10:1.

[0027] Example 6 The preparation method of Example 6 is the same as that of Example 2, except that: in step (3), under sterile conditions, the homogeneous liquid obtained in step (2) is added to the fermentation tank, and Lactobacillus plantarum and Yersinia lipolytica are inoculated into the fermentation tank at a total inoculation amount of 6%. The fermentation is carried out at a temperature of 30°C and a pH of 6.5 for 2 hours, sterilized, and separated. The oil phase after separation is the self-emulsifying plant fermented oil; wherein, the inoculation ratio of Lactobacillus plantarum and Yersinia lipolytica is 5.8:0.2.

[0028] Example 7 The method for preparing self-emulsifying fermented vegetable oil in this embodiment includes the following steps: (1) Camellia seed oil and water were mixed at a weight ratio of 1:4 and then Rhizopus milchii lipase was added. The mixture was hydrolyzed at 40°C and pH 7.5 for 3 hours. After enzyme inactivation, the hydrolysate was obtained. The weight percentage of monoglyceride in the hydrolysate was 2.5%. The weight ratio of the camellia seed oil to the Rhizopus miltiorrhizos lipase is 10:1. (2) Add soybean lecithin to the enzymatic hydrolysis product obtained in step (1), transfer it to a high-pressure homogenizer, and cycle it twice at 40°C and 110 MPa to obtain a homogenized liquid; wherein the amount of soybean lecithin added is: the weight ratio of soybean lecithin to the enzymatic hydrolysis product is 1:7. (3) Under aseptic conditions, the homogenized liquid obtained in step (2) is added to the fermenter, and Lactobacillus plantarum and Yersinia lipolytica are inoculated into the fermenter at a total inoculation amount of 8%. The fermentation is carried out at a temperature of 30°C and a pH of 6.5 for 10 hours. After sterilization and separation, the oil phase is taken to obtain an oily liquid. The inoculation ratio of Lactobacillus plantarum and Yersinia lipolytica is 3:1. First, dissolve chitosan in an aqueous citric acid solution to obtain a chitosan solution (adjust the amount of citric acid added to make the solution pH 6). Then, dissolve sodium tripolyphosphate in water to obtain a sodium tripolyphosphate solution. Add the obtained chitosan solution and sodium tripolyphosphate solution to the oily liquid. Stir at 100 rpm in a magnetic stirrer for 10 minutes until the mixture is homogeneous to obtain a self-emulsifying plant fermentation oil encapsulated in a carrier. The weight ratio of the oily liquid, chitosan, sodium tripolyphosphate, and water is 30:1:0.2:300.

[0029] Example 8 The preparation method of Example 8 is the same as that of Example 7, except that the weight ratio of oily liquid, chitosan, sodium tripolyphosphate and water is 40:2:0.5:400.

[0030] Comparative Example 1 The preparation method of Comparative Example 1 is the same as that of Example 1, except that in step (1), the Mihegensis lipase is replaced with cellulase.

[0031] Comparative Example 2 The preparation method of Comparative Example 2 is the same as that of Example 1, except that in step (1), the lipase of Rhizopus micranthum is replaced with exogenous monoglyceride (2-monostearylglycerol (CAS 621-61-4), standard, purity ≥95%), and the amount of exogenous monoglyceride added is 3.5% by weight in the mixture of camellia seed oil and water.

[0032] Comparative Example 3 The preparation method of Comparative Example 3 is the same as that of Example 2, except that in step (1), the lipase of Rhizopus micranthum is replaced with exogenous monoglyceride (2-monostearylglycerol (CAS 621-61-4), standard, purity ≥95%), and the amount of exogenous monoglyceride added is 2.5% by weight in the mixture of camellia seed oil and water.

[0033] Effect Experiment Example To verify the technical effect of the self-emulsifying fermented vegetable oil described in this invention, the following experiments were conducted: Following the methods used in Examples 1-8 and Comparative Examples 1-3 for preparing fermented vegetable oils, self-emulsifying fermented vegetable oils were prepared, and the following experiments were conducted: Take 1 ml of each of the self-emulsifying plant fermented oils prepared in Examples 1-6 and Comparative Examples 1-3, add them to 10 ml of water, and stir in a magnetic stirrer at 100 rpm for 10 min until they are mixed evenly. These are used as Experimental Examples 1-6 and Control Examples 1-3. Take 11 ml of each of the self-emulsifying plant fermented oils prepared in Examples 7-8, and use them as Experimental Examples 7-8.

[0034] Test 1: Centrifuge the emulsions of Experimental Examples 1-8 and Control Examples 1-3 at 5000 r / min for 15 min, observe the layering of the samples, and calculate the emulsion height retention rate (%) after centrifugation.

[0035] Emulsion height retention rate after centrifugation (%) = height of emulsion layer after centrifugation / total height of emulsion layer before centrifugation x 100%; where, the height of the emulsion layer after centrifugation in this test example refers to the height of the volume occupied by the part of the system that still maintains a uniform emulsion and has not undergone phase separation after centrifugation.

[0036] Table 1. Test results of emulsion high retention rate after centrifugation

[0037] Test 2: The emulsions of Experimental Examples 1-8 and Control Examples 1-3 were placed alternately at 45°C and 4°C, and the cycle was repeated every 24 hours for a total of 14 days to simulate long-term storage. The color change and peroxide value change of the emulsion were recorded on the 1st, 7th and 14th days (that is, at the end of the 1st cycle, the 7th cycle and the 14th cycle).

[0038] The peroxide value (POV) was determined using the iodometric method.

[0039] Table 2. Test results of changes in emulsion color and peroxide value.

[0040] According to the results in Tables 1-2, the self-emulsifying fermented vegetable oil obtained by the preparation method of the present invention can spontaneously form a stable emulsion under gentle stirring / without violent external force, and has good emulsification stability and storage stability.

[0041] Based on the results of Experimental Examples 1-2 and Control Examples 2-3, it can be seen that in the first stage, the direct addition of exogenous monoglycerides has varying degrees of impact on the overall performance of the product. The possible reason is that Examples 1-2 utilize 1,3-position specific lipases to enzymatically hydrolyze triglycerides in situ to generate monoglycerides, which have good compatibility with the oil phase. During high-pressure homogenization, they can quickly adsorb onto the surface of oil droplets, forming a uniform composite film with phospholipid molecules. In contrast, exogenous monoglycerides have relatively poor compatibility with camellia seed oil, are prone to aggregation and uneven distribution, and may be partially decomposed during fermentation. Therefore, the stability of the final composite film formed by exogenous monoglycerides is worse than that of the former.

[0042] Compared with Example 1, which only added soybean lecithin, the prepared plant fermented oil showed poor emulsification and storage stability. This may be because the gaps between phospholipid molecules in the phospholipid membrane are large and the interfacial membrane strength is insufficient, which makes the emulsion easy to separate and break down during centrifugation or storage. Comparing the results of Experiment 2 and Experiments 5-6, it can be seen that if the amount of monoglycerides produced by the first stage of enzymatic hydrolysis is too small, or if the amount of monoglycerides produced by the second stage of fermentation is insufficient, it will have a certain impact on the emulsification and storage stability of the plant fermented oil.

[0043] According to the results of Experiments 2 and 7-8, the addition of chitosan and sodium tripolyphosphate is beneficial to further enhance the membrane strength and inhibit the oxidation rate of plant fermentation oil, thereby improving its emulsification stability and storage stability.

[0044] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are encompassed by this invention.

Claims

1. A method for preparing a self-emulsifying fermented vegetable oil, characterized in that, Includes the following steps: (1) After mixing vegetable oil with water, add biological enzyme, perform enzymatic hydrolysis and enzyme inactivation to obtain enzymatic hydrolysis product; wherein, the biological enzyme is a 1,3 position specific lipase; (2) Add phospholipids to the enzymatic hydrolysis product obtained in step (1), homogenize under high pressure to obtain a homogenized liquid; (3) Add fermentation bacteria to the homogenized liquid obtained in step (2), and carry out fermentation, sterilization and separation to obtain the self-emulsifying plant fermented oil.

2. The self-emulsifying fermented vegetable oil according to claim 1, characterized in that, In step (1), the vegetable oil is camellia seed oil or olive oil; Optionally, the weight ratio of the vegetable oil to the water is 1:(2-5).

3. The self-emulsifying fermented vegetable oil according to claim 1, characterized in that, In step (1), the 1,3 position specific lipase is selected from either *Mucor miltiorrhiza* lipase or *Candida antarcticis* lipase B. Optionally, the weight ratio of the vegetable oil to the 1,3-position specific lipase is (10-100):

1.

4. The self-emulsifying fermented vegetable oil according to claim 1, characterized in that, In step (1), the enzymatic hydrolysis conditions are: at a temperature of 35-45℃ and a pH of 7-8, the enzymatic hydrolysis lasts for 2-4 hours. Optionally, the enzymatic hydrolysis endpoint is when the weight percentage of monoglycerides in the enzymatic hydrolysis product is 2%-3.5%.

5. The self-emulsifying fermented vegetable oil according to claim 1, characterized in that, In step (2), the phospholipid is selected from one or more of soybean phospholipids, egg yolk lecithin, and hydrogenated lecithin; Optionally, the phospholipid is soybean phospholipid, and the weight ratio of the enzymatic hydrolysis product to the soybean phospholipid is (6-8):

1.

6. The self-emulsifying fermented vegetable oil according to claim 1, characterized in that, In step (2), the conditions for high-pressure homogenization are 40-45℃, 100-120Mpa, and 2-3 cycles.

7. The self-emulsifying fermented vegetable oil according to claim 1, characterized in that, In step (3), the fermentation bacteria are a compound bacterial agent, including any one of Lactobacillus plantarum, Saccharomyces cerevisiae, Bifidobacterium, and Yersinia lipolytica; Optionally, the fermentation bacteria consist of Lactobacillus plantarum and Yersinia lipolytica; Optionally, the inoculation ratio of *Lactobacillus plantarum* to *Yersinia lipophila* is (2-4):1; Optionally, the fermentation is carried out at a total inoculum of 3-8% for 8-12 hours at a temperature of 28-35°C and a pH of 5.5-6.

5.

8. The self-emulsifying fermented vegetable oil according to claim 1, characterized in that, Step (3) also includes the step of adding chitosan and sodium tripolyphosphate: adding fermentation bacteria to the homogeneous liquid obtained in step (2), fermenting, sterilizing and separating to obtain an oily liquid, adding chitosan, sodium tripolyphosphate, citric acid and water to the oily liquid, mixing evenly to obtain a self-emulsifying plant fermented oil encapsulated in a carrier.

9. The self-emulsifying fermented vegetable oil according to claim 8, characterized in that, The weight ratio of the oily liquid, chitosan, sodium tripolyphosphate, and water is (30-40):(1-2):(0.1-1):(250-500).

10. A self-emulsifying fermented vegetable oil, obtained by the preparation method according to any one of claims 1-9.

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