Method for stabilizing high-internal-phase oil-in-water emulsion through ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine

Abstract

The invention discloses a method for stabilizing high-internal-phase oil-in-water emulsion through ionic crosslinking of phenylalanine-aspartic acid copolymer / polylysine, and belongs to the fields of peptide surfactants and surface physicochemistry. According to the preparation method of the high-internal-phase oil-in-water emulsion, a phenylalanine-aspartic acid copolymer / polylysine aqueous solution is adopted as a water phase and is mixed with an oil phase to obtain a mixed system, and the volume ratio of the oil phase to the water phase is (7-9): (1-3); and then homogenizing the mixed system, heating at 60-90 DEG C for 2-6 hours after homogenizing, and naturally cooling to obtain the high internal phase oil-in-water emulsion with stable phenylalanine-aspartic acid copolymer / polylysine ionic crosslinking. The high-internal-phase oil-in-water emulsion has good stability, and can be stabilized for 6-24 months in a pH range of 1-11.

Description

Technical Field

[0001] The invention relates to a method for stabilizing a high internal phase oil-in-water emulsion by ion cross-linking a phenylalanine-aspartic acid copolymer and polylysine, and belongs to the fields of peptide surfactants and surface physical chemistry. Background Art

[0002] High Internal Phase Emulsion (HIPE) usually refers to an emulsion with an internal phase volume fraction greater than 74%. Since the volume of the discontinuous phase of the high internal phase emulsion is too high, the internal droplet size of the emulsion will be uneven or deformed. Some particle-stabilized Pickering high internal phase emulsions will undergo a phase reversal as the internal phase volume increases, while high internal phase emulsions stabilized by surfactant molecules will continue to stabilize the emulsion or demulsify as the internal phase volume increases. Due to the low proportion of the continuous phase, high internal phase emulsions often have high viscosity, so they are also called gel emulsions.

[0003] Emulsifiers used to prepare high internal phase emulsions in the prior art include synthetic polymers or inorganic particles, etc., but their application in cosmetics, pharmaceuticals and food industries is limited due to their biological toxicity. Therefore, the development of environmentally friendly biocompatible particles as effective stabilizers has received special attention in recent years. Protein and polysaccharide derivatives in nature can be used as emulsifiers for high internal phase emulsions. Usually, protein particles stabilize oil-in-water (O / W) high internal phase emulsions. High internal phase emulsions have a larger discontinuous phase surface area than ordinary emulsions of the same volume. Utilizing this characteristic of high internal phase emulsions, high internal phase emulsions can be used as templates for porous materials, organic semiconductors, filtration membranes, tissue engineering scaffolds, food and drug delivery systems.

[0004] Zou Yanan (Food Science and Technology, 2022, 47(7): 129-133.) studied the effect of mung bean protein peptides with different hydrolysis degrees on the 10-minute stability of water-in-oil emulsions at pH 7.0. The results showed that with the increase of hydrolysis degree, the emulsification activity, emulsification stability, Zeta potential and surface hydrophobicity of the emulsion showed a trend of first increasing and then decreasing. Wang Dan et al. (China Oils and Fats, 2024(003): 049.) studied the Pickering emulsion stability of soybean peptide nanoparticles (SPN). SPN was prepared by ultrasonic method using soybean peptide aggregates as raw materials. Soybean protein isolate (SPI) was introduced into the SPN system to construct a composite emulsifier. The effect of SPI on the interfacial activity of SPN and the 15-day emulsification stability under neutral pH conditions at different emulsifier mass concentrations was studied. Chinese patent CN202111548661.4 discloses that walnut meal is used as raw material, after defatting, alkali extraction and acid precipitation, trypsin is used for restricted enzymatic hydrolysis, and finally ultrafiltration separation and polysaccharide gel G25 gel chromatography separation and purification are used to obtain walnut polypeptides, and the emulsification properties under neutral conditions are investigated. CN201811525882.8 discloses a chitosan casein phosphopeptide composite nanoparticle stabilized Pickering high internal phase emulsion and its preparation. The emulsion stability is more than six months in the pH range of 4 to 6. However, the peptide emulsions reported in these prior art reports usually have a short stability period, or the emulsions have weak resistance to pH changes and can only maintain the emulsion within a limited pH range. In addition, the preparation of peptides from proteolysis requires strict control of the reaction conditions to ensure that the composition of each batch of products is roughly the same. Summary of the invention

[0005] [Technical issues]

[0006] The stabilizers used in the prior art for stabilizing Pickering high internal phase emulsions often have complicated preparation processes and unclear ingredients. Although they can maintain the stability of Pickering emulsions to a certain extent, their stability period is short or the emulsions are weak in their ability to withstand pH changes, and can only maintain the emulsions within a limited pH range. In view of the defects and deficiencies of the prior art, the present invention provides a method for stabilizing a high internal phase water-in-oil emulsion by ionic crosslinking of a phenylalanine-aspartic acid copolymer and polylysine. The method uses a centrifugal pairing of the aspartic acid β-carboxyl group of the phenylalanine-aspartic acid copolymer and the amino group of the polylysine to form a crosslinking reaction (as shown below). Figure 1 The prepared high internal phase oil-in-water emulsion is stable in the range of pH = 1 to 11 for 6 to 24 months.

[0007] [Technical solution]

[0008] In order to achieve the above purpose, the following technical solutions are adopted:

[0009] A method for stabilizing a high internal phase oil-in-water emulsion by ionic crosslinking of a phenylalanine-aspartic acid copolymer and polylysine, the method comprising the following steps:

[0010] (1) preparing an aqueous solution of phenylalanine-aspartic acid copolymer and polylysine as an aqueous phase;

[0011] (2) mixing the oil phase with the aqueous phase of step (1) to obtain a mixed system, wherein the volume ratio of the oil phase to the aqueous phase is 7-9:1-3; then homogenizing the mixed system, heating it at 60-90° C. for 2-6 hours after homogenization, and naturally cooling it to obtain a high internal phase oil-in-water emulsion that is stable by ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine.

[0012] In one embodiment, the concentration of the phenylalanine-aspartic acid copolymer in the aqueous phase of step (1) is 0.5-6 g / L, and the concentration of lysine is 0.075-1 g / L.

[0013] In one embodiment, the pH value of the aqueous phase in step (1) is 1-11.

[0014] In one embodiment, the molecular weight of the polylysine in step (1) is 30,000Da to 300,000Da; preferably 30,000Da to 70,000Da or 70,000Da to 150,000Da or 150,000Da to 300,000Da.

[0015] In one embodiment, the preparation process of the phenylalanine-aspartic acid copolymer in step (1) is as follows: L-phenylalanine methyl ester hydrochloride and L-aspartic acid dimethyl ester hydrochloride are added to a disodium hydrogen phosphate-citric acid buffer, and a protease is added, and the mixture is stirred and reacted at 25-55° C. for 3-6 hours. After the reaction is completed, the reaction solution is centrifuged, and the precipitate is taken, and washed three times with 3-5 times the volume of deionized water and anhydrous ethanol, centrifuged and freeze-dried to obtain a random copolymer; the obtained random copolymer is placed in dichloromethane / methanol, NaOH is added, and the mixture is stirred and reacted at 25-65° C. for 0.5-2 hours. After the reaction is completed, the reaction compound is subjected to reduced pressure rotary evaporation to obtain a phenylalanine-aspartic acid copolymer.

[0016] In one embodiment, the mass volume ratio of L-phenylalanine methyl ester hydrochloride to L-aspartic acid dimethyl ester hydrochloride to disodium hydrogen phosphate-citric acid buffer is 4.3-6.5:7.9-23.7:60-150; g:g:mL.

[0017] In one embodiment, the sodium hydrogen phosphate-citrate buffer has a concentration of 0.2 to 0.5 mol / L and a pH of 6.5 to 9.0.

[0018] In one embodiment, the protease is any one of bromelain, papain, neutral protease, and alkaline protease.

[0019] In one embodiment, the mass ratio of the protease to L-phenylalanine methyl ester hydrochloride and L-aspartic acid dimethyl ester hydrochloride is 0.5-2.5:4.3-6.5:7.9-23.7.

[0020] In one embodiment, the centrifugation conditions are: 5000-8000 rpm, time 5-10 min.

[0021] In one embodiment, the volume ratio of methane / methanol is 6:1 to 9:1.

[0022] In one embodiment, the mass ratio of NaOH to L-phenylalanine methyl ester hydrochloride and L-aspartic acid dimethyl ester hydrochloride is 0.8-6:4.3-6.5:7.9-23.7.

[0023] In one embodiment, the oil phase in step (2) is any one of n-octane, squalane, camellia oil, coconut oil, and soybean oil.

[0024] In one embodiment, the oil-to-water volume ratio in step (2) is 7.4:2.6 or 8:1 or 9:1.

[0025] In one embodiment, the homogenization conditions in step (3) are: 10000-15000 rpm, 2-5 min.

[0026] The present invention also provides a phenylalanine-aspartic acid copolymer and polylysine ion cross-linked stable high internal phase water-in-oil emulsion prepared by the above method.

[0027] The present invention also provides the use of the phenylalanine-aspartic acid copolymer and polylysine ion cross-linked stable high internal phase oil-in-water emulsion in the cosmetics, pharmaceutical and food industries.

[0028] Beneficial effects:

[0029] The invention adopts the centrifugal pairing of aspartic acid β-carboxyl groups of phenylalanine-aspartic acid copolymer and amino groups of polylysine to crosslink, so as to stabilize the oil-water interface and form a stable high inward oil-in-water emulsion. The phenylalanine-aspartic acid copolymer is synthesized by an enzyme catalysis method, the process is simple, and the raw materials are easy to obtain. The prepared phenylalanine-aspartic acid copolymer and polylysine stabilized high internal phase oil-in-water emulsion has high stability and can be stable for 6 to 24 months within the range of pH=1 to 11. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1Schematic diagram of ionic crosslinking between the β-carboxyl group of aspartic acid and the amino group of polylysine in the present invention;

[0031] Figure 2 This is a physical diagram of the stability of the high internal phase oil-in-water emulsion stabilized by ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine prepared in Example 1; the number on the bottle cap represents the pH value;

[0032] Figure 3 This is a physical diagram of the stability of the high internal phase oil-in-water emulsion stabilized by ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine prepared in Example 2; the number on the bottle cap represents the pH value;

[0033] Figure 4 This is a physical picture of the stability of the high internal phase oil-in-water emulsion stabilized by ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine prepared in Example 3; the number on the bottle cap represents the pH value;

[0034] Figure 5 This is a physical picture of the stability of the high internal phase oil-in-water emulsion stabilized by the alanine-aspartic acid copolymer prepared in Comparative Example 1; the number on the bottle cap represents the pH value;

[0035] Figure 6 This is a physical picture of the stability of the high internal phase oil-in-water emulsion stabilized by alanine-aspartic acid copolymer prepared in Comparative Example 2; the number on the bottle cap represents the pH value. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. The following specific implementation methods further describe the present invention.

[0037] The raw material sources involved in the present invention are:

[0038] Bromelain, enzyme activity of 300 U / mg, purchased from Shanghai Titan Technology Co., Ltd., product model 013632032;

[0039] Papain, enzyme activity of 800000U / g, purchased from Shanghai Titan Technology Co., Ltd., product model 011344050;

[0040] Alkaline protease, with an enzyme activity of 200 U / mg, was purchased from Beijing Bioson Biotechnology Co., Ltd., product model D13102.

[0041] Example 1

[0042] The method for synthesizing a phenylalanine-aspartic acid copolymer by protease catalysis specifically comprises the following steps:

[0043] (1) Add 4.3 g of L-phenylalanine methyl ester hydrochloride and 7.9 g of L-aspartic acid dimethyl ester hydrochloride to 60 mL of disodium hydrogen phosphate-citric acid buffer (0.2 mol / L, pH = 6.5), add 0.5 g of bromelain, and stir (1000 rpm) at 25° C. for 3 h. After the reaction, centrifuge the reaction mixture (6 min, 8000 rpm), take the precipitate, wash it three times with 3 volumes of deionized water and anhydrous ethanol, centrifuge (6 min, 8000 rpm) and freeze-dry to obtain a random copolymer;

[0044] (2) The obtained random copolymer was placed in 40 ml of dichloromethane / methanol (volume ratio of 6:1), 0.8 g of NaOH was added, and the mixture was stirred (1000 rpm) at 25° C. for 0.5 h. After the reaction was completed, the reaction product was subjected to vacuum rotary evaporation to obtain a phenylalanine-aspartic acid copolymer.

[0045] A method for ion crosslinking and stabilizing a high internal phase oil-in-water emulsion by phenylalanine-aspartic acid copolymer and polylysine, specifically comprising the following steps:

[0046] (1) An aqueous solution (aqueous phase) of phenylalanine-aspartic acid copolymer and polylysine was prepared in a 10 mL columnar sample bottle; the concentration of phenylalanine-aspartic acid copolymer in the aqueous solution was 0.5 g / L, and the concentration of polylysine (molecular weight range: 30000-70000 Da, Beijing Bio-Ray Biotechnology Co., Ltd.) was 0.075 g / L; the pH of the aqueous solution was adjusted to 1-11 with 0.1 mol / L HCl or 0.1 mol / L NaOH aqueous solution;

[0047] (2) transferring n-octane and mixing it with the aqueous phase of step (1) to make the total volume of the oil-water phase be 7 mL and the oil-water volume ratio be 7.4:2.6, thereby obtaining a mixed system; mechanically emulsifying the mixed system on an ULTRA-TURRAX T18 basic homogenizer (IKA, Germany) at a rotation speed of 10,000 rpm for 2 min, heating the homogenized mixed system at 60° C. for 2 hours, and naturally cooling to obtain a high internal phase oil-in-water emulsion stabilized by ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine.

[0048] The high internal phase oil-in-water emulsion prepared in this example is stable for 6 months in the range of pH value of the aqueous phase = 1 to 11. Figure 2 shown.

[0049] Example 2

[0050] The method for synthesizing a phenylalanine-aspartic acid copolymer by protease catalysis specifically comprises the following steps:

[0051] (1) Add 6.5 g of L-phenylalanine methyl ester hydrochloride and 23.7 g of L-aspartic acid dimethyl ester hydrochloride to 150 mL of disodium hydrogen phosphate-citric acid buffer (0.5 mol / L, pH = 9.0), add 2.5 g of papain, and react at 55° C. with stirring (1000 rpm) for 6 h. After the reaction is completed, the reaction mixture is centrifuged (6 min, 8000 rpm), the precipitate is taken, washed three times with 5 volumes of deionized water and anhydrous ethanol, centrifuged (6 min, 8000 rpm) and freeze-dried to obtain a random copolymer;

[0052] (2) The obtained random copolymer was placed in 100 ml of dichloromethane / methanol (volume ratio of 9:1), 6 g of NaOH was added, and the mixture was stirred (1000 rpm) at 65° C. for 0.5 h. After the reaction was completed, the reaction product was subjected to reduced pressure rotary evaporation to obtain a phenylalanine-aspartic acid copolymer.

[0053] A method for ion crosslinking and stabilizing a high internal phase oil-in-water emulsion by phenylalanine-aspartic acid copolymer and polylysine, specifically comprising the following steps:

[0054] (1) In a 10 mL columnar sample bottle, an aqueous solution of phenylalanine-aspartic acid copolymer and polylysine (aqueous phase) was prepared, wherein the concentration of phenylalanine-aspartic acid copolymer in the aqueous solution was 6 g / L, and the concentration of polylysine (molecular weight range: 150,000-300,000 Da, Beijing Bio-Ray Biotechnology Co., Ltd.) was 1 g / L; the pH of the aqueous phase was adjusted to 1-11 with 0.1 mol / L HCl or 0.1 mol / L NaOH aqueous solution;

[0055] (2) Pipette squalane and mix it with the water phase of step (1) to make the total volume of the oil-water phase be 7 mL and the oil-water volume ratio be 9:1, thereby obtaining a mixed system; the mixed system is mechanically emulsified for 5 min at a speed of 15000 rpm on an ULTRA-TURRAX T18 basic homogenizer (IKA, Germany), and the homogenized mixture is heated at 90° C. for 2 hours. After natural cooling, a high internal phase oil-in-water emulsion having stable ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine is obtained.

[0056] The high internal phase oil-in-water emulsion prepared in this example is stable for 24 months in the range of pH value of the aqueous phase = 1 to 11. Figure 3 shown.

[0057] Example 3

[0058] The method for synthesizing a phenylalanine-aspartic acid copolymer by protease catalysis specifically comprises the following steps:

[0059] (1) Add 5 g of L-phenylalanine methyl ester hydrochloride and 15 g of L-aspartic acid dimethyl ester hydrochloride to 100 mL of disodium hydrogen phosphate-citric acid buffer (00.3 mol / L, pH = 8.0), add 1 g of alkaline protease, and react at 35° C. with stirring (1000 rpm) for 4 h. After the reaction is completed, the reaction mixture is centrifuged (6 min, 8000 rpm), the precipitate is taken, washed three times with 4 volumes of deionized water and anhydrous ethanol, centrifuged (6 min, 8000 rpm) and freeze-dried to obtain a random copolymer;

[0060] (2) The obtained random copolymer was placed in 80 ml of dichloromethane / methanol (volume ratio of 8:1), 5 g of NaOH was added, and the mixture was stirred (1000 rpm) at 35° C. for 2 h. After the reaction was completed, the reaction product was subjected to reduced pressure rotary evaporation to obtain a phenylalanine-aspartic acid copolymer.

[0061] A method for ionically crosslinking a phenylalanine-aspartic acid copolymer and polylysine to stabilize a high internal phase oil-in-water emulsion comprises the following steps:

[0062] (1) An aqueous solution (aqueous phase) of phenylalanine-aspartic acid copolymer and polylysine was prepared in a 10 mL columnar sample bottle; the concentration of phenylalanine-aspartic acid copolymer in the aqueous solution was 3 g / L, and the concentration of polylysine (molecular weight range: 70000-150000 Da, Beijing Bio-Ray Biotechnology Co., Ltd.) was 0.8 g / L, and the pH of the aqueous phase was adjusted to 1-11 with 0.1 mol / L HCl or 0.1 mol / L NaOH aqueous solution;

[0063] (2) Coconut oil was transferred and mixed with the aqueous phase of step (1) to make the total volume of the oil-water phase be 7 mL and the oil-water volume ratio be 8:1, thereby obtaining a mixed system; the mixed system was mechanically emulsified for 3 min at a rotation speed of 12000 rpm on an ULTRA-TURRAX T18 basic homogenizer (IKA, Germany), and the homogenized mixed system was heated at 70° C. for 4 hours. After natural cooling, a high internal phase oil-in-water emulsion with stable ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine was obtained.

[0064] The high internal phase oil-in-water emulsion prepared in this example is stable for 12 months in the range of pH value of the aqueous phase = 1 to 11. Figure 4 shown.

[0065] Comparative Example 1

[0066] A method for stabilizing a high internal phase oil-in-water emulsion using a phenylalanine-aspartic acid copolymer comprises the following steps:

[0067] (1) Add 4.3 g of L-phenylalanine methyl ester hydrochloride and 7.9 g of L-aspartic acid dimethyl ester hydrochloride to 60 mL of disodium hydrogen phosphate-citric acid buffer (0.2 mol / L, pH = 6.5), add 0.5 g of bromelain, and stir (1000 rpm) at 25° C. for 3 h. After the reaction, centrifuge the reaction mixture (6 min, 8000 rpm), take the precipitate, wash it three times with 3 volumes of deionized water and anhydrous ethanol, centrifuge (6 min, 8000 rpm) and freeze-dry to obtain a random copolymer;

[0068] (2) the obtained random copolymer was placed in 40 ml of dichloromethane / methanol (volume ratio of 6:1), 0.8 g of NaOH was added, and the mixture was stirred (1000 rpm) at 25° C. for 0.5 h. After the reaction was completed, the reaction product was subjected to vacuum rotary evaporation to obtain a phenylalanine-aspartic acid copolymer;

[0069] (3) preparing an aqueous solution (aqueous phase) of a phenylalanine-aspartic acid copolymer in a 10 mL columnar sample bottle; the concentration of the phenylalanine-aspartic acid copolymer in the aqueous solution is 0.5 g / L, and adjusting the pH of the aqueous solution to 1 to 11 with 0.1 mol / L HCl or 0.1 mol / L NaOH aqueous solution;

[0070] (4) Pipette n-octane and mix it with the water phase of step (1) to make the total volume of the oil-water two phases 7 mL and the oil-water volume ratio 7.4:2.6 to obtain a mixed system; the mixed system is mechanically emulsified on an ULTRA-TURRAX T18 basic homogenizer (IKA, Germany) at a speed of 10000 rpm for 2 min to obtain a high internal phase oil-in-water emulsion stabilized by phenylalanine-aspartic acid copolymer.

[0071] The high internal phase oil-in-water emulsion prepared in this comparative example has a separation phenomenon after 15 days in the range of pH value of the water phase = 1 to 11, and the emulsion has obvious instability, such as Figure 5 shown.

[0072] Comparative Example 2

[0073] A method for stabilizing a high internal phase oil-in-water emulsion using a phenylalanine-aspartic acid copolymer comprises the following steps:

[0074] (1) Add 6.5 g of L-phenylalanine methyl ester hydrochloride and 23.7 g of L-aspartic acid dimethyl ester hydrochloride to 150 mL of disodium hydrogen phosphate-citric acid buffer (0.5 mol / L, pH = 9.0), add 2.5 g of papain, and react at 55° C. with stirring (1000 rpm) for 6 h. After the reaction is completed, the reaction mixture is centrifuged (6 min, 8000 rpm), the precipitate is taken, washed three times with 5 volumes of deionized water and anhydrous ethanol, centrifuged (6 min, 8000 rpm) and freeze-dried to obtain a random copolymer;

[0075] (2) The obtained random copolymer was placed in 100 ml of dichloromethane / methanol (volume ratio of 9:1), 6 g of NaOH was added, and the mixture was stirred (1000 rpm) at 65° C. for 0.5 h. After the reaction was completed, the reaction product was subjected to reduced pressure rotary evaporation to obtain a phenylalanine-aspartic acid copolymer.

[0076] (3) preparing an aqueous solution (aqueous phase) of a phenylalanine-aspartic acid copolymer in a 10 mL columnar sample bottle, wherein the concentration of the phenylalanine-aspartic acid copolymer in the aqueous solution is 6 g / L, and adjusting the pH of the aqueous phase to 1 to 11 with 0.1 mol / L HCl or 0.1 mol / L NaOH aqueous solution;

[0077] (4) Pipette squalane and mix it with the water phase of step (1) to make the total volume of the oil-water two phases 7 mL and the oil-water volume ratio 9:1 to obtain a mixed system; the mixed system is mechanically emulsified on an ULTRA-TURRAX T18 basic homogenizer (IKA, Germany) at a speed of 15000 rpm for 5 min to obtain a high internal phase oil-in-water emulsion stabilized by phenylalanine-aspartic acid copolymer.

[0078] The high internal phase oil-in-water emulsion prepared in this comparative example has a pH of 1 to 11 in the water phase, and separation occurs after 15 days. The emulsion has obvious instability, such as Figure 6 shown.

[0079] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for stabilizing a high internal phase oil-in-water emulsion by ionic crosslinking of a phenylalanine-aspartic acid copolymer and polylysine, characterized in that: The method comprises the following steps: (1) preparing an aqueous solution of phenylalanine-aspartic acid copolymer and polylysine as an aqueous phase; (2) mixing the oil phase with the aqueous phase of step (1) to obtain a mixed system, wherein the volume ratio of the oil phase to the aqueous phase is 7-9:1-3; then homogenizing the mixed system, heating it at 60-90° C. for 2-6 hours after homogenization, and naturally cooling it to obtain a high internal phase oil-in-water emulsion that is stable by ionic crosslinking of phenylalanine-aspartic acid copolymer and polylysine.

2. The method according to claim 1, characterized in that: The concentration of the phenylalanine-aspartic acid copolymer in the aqueous phase of step (1) is 0.5-6 g / L, and the concentration of lysine is 0.075-1 g / L.

3. The method according to claim 1, characterized in that: The pH value of the aqueous phase in step (1) is 1 to 12.

4. The method according to claim 1, characterized in that: The molecular weight of the polylysine in step (1) is 30000Da to 300000Da.

5. The method according to claim 1, characterized in that The preparation process of the phenylalanine-aspartic acid copolymer in step (1) is as follows: L-phenylalanine methyl ester hydrochloride and L-aspartic acid dimethyl ester hydrochloride are added to a disodium hydrogen phosphate-citric acid buffer, and a protease is added, and the mixture is stirred and reacted at 25-55° C. for 3-6 hours. After the reaction is completed, the reaction solution is centrifuged, and the precipitate is taken, and washed three times with 3-5 times the volume of deionized water and anhydrous ethanol, and then centrifuged and freeze-dried to obtain a random copolymer; the obtained random copolymer is placed in dichloromethane / methanol, and NaOH is added, and the mixture is stirred and reacted at 25-65° C. for 0.5-2 hours. After the reaction is completed, the reaction compound is subjected to reduced pressure rotary evaporation to obtain a phenylalanine-aspartic acid copolymer.

6. The method according to claim 5, characterized in that The mass volume ratio of L-phenylalanine methyl ester hydrochloride to L-aspartic acid dimethyl ester hydrochloride to disodium hydrogen phosphate-citric acid buffer is 4.3-6.5:7.9-23.7:60-150; g:g:mL.

7. The method according to claim 5, characterized in that The protease is any one of bromelain, papain, neutral protease and alkaline protease.

8. The method according to claim 1, characterized in that: The oil phase in step (2) is any one of n-octane, squalane, camellia oil, coconut oil and soybean oil.

9. A high internal phase oil-in-water emulsion prepared by the method according to any one of claims 1 to 8.

10. Use of the high internal phase oil-in-water emulsion according to claim 9 in cosmetics, pharmaceuticals and food industries.

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