Application of soybean folic acid enrichment method in folic acid-rich soybean milk

Abstract

The invention relates to the technical field of soybean milk products, in particular to application of a soybean folic acid enrichment method in soybean milk rich in folic acid. According to the method disclosed by the invention, a plant biotransformation technology is utilized, and folic acid in the soybeans is enriched by cleaning and soaking the soybeans, adding a substrate and a hypertonic substance and regulating and controlling the temperature and activating folic acid synthetase. The preparation method comprises the following steps: germinating soybeans for 24-36 hours, homogenizing, adding wheat germs and an additive, boiling the soybean milk, blending, homogenizing and sterilizing to obtain a stable healthy product with high folic acid content.

Description

Technical Field

[0001] The invention relates to the technical field of soybean milk products, and in particular to application of a soybean folic acid enrichment method in folic acid-rich soybean milk. Background Art

[0002] Folic acid is a water-soluble B vitamin that is essential for organisms. It mainly exists in the form of tetrahydrofolate (THF) and its derivatives. In the one-carbon metabolism of organisms, folic acid plays an important role. As a cofactor of one-carbon transfer reactions, it participates in the synthesis of nucleotides, the metabolism of amino acids (e.g., the conversion of serine to glycine, the decomposition of histidine), and the methylation cycle (e.g., the conversion of homocysteine ​​to methionine through remethylation). In the methylation cycle, folic acid provides a large amount of methyl groups and substances required for methylation reactions. Therefore, folic acid and its synthesis pathway are essential for cell metabolism. Since the human body cannot synthesize folic acid on its own, it can only be ingested through diet. In order to meet normal physiological needs, adults need to supplement 400 micrograms of folic acid per day, while pregnant women need to supplement 600 micrograms per day. Studies have shown that insufficient folic acid intake may lead to megaloblastic anemia and fetal neural tube defects (NTDs). At the same time, low levels of folic acid intake are closely related to the occurrence of Alzheimer's disease, cardiovascular disease and various cancers. Therefore, folic acid plays an extremely important role in maintaining normal life activities of the human body.

[0003] Plant foods, such as soybeans, rice and tomatoes, contain only a small amount of folic acid, but the folic acid content can be increased through genetic engineering or seed germination. Doing so can enhance the nutritional value and health benefits of plant-based foods. After seed germination, the life metabolic activities in the plant body begin to become active, and a large number of proenzymes are activated, triggering a series of physiological and biochemical changes. For example, in legumes, lipids are broken down into glycerol and fatty acids under the action of enzymes, and eventually converted into sugars that can be absorbed by the human body. At the same time, proteins are broken down into peptides and amino acids, which helps the body absorb them. In addition, the content of physiologically active ingredients such as vitamins, γ-aminobutyric acid, and isoflavones will also increase accordingly.

[0004] CN109418422A discloses a folic acid-rich soy milk and a production technology thereof, which is characterized in that soybean seeds are sprayed with a citric acid buffer solution of a specific pH and germinated at a certain temperature and culture time, wherein folic acid is enriched; the germinated soybeans rich in folic acid are used as raw materials, after pulping, sodium ascorbate, white sugar, xanthan gum, sodium carboxymethyl cellulose, sucrose fatty acid esters and monoglycerides are added, and then secondary homogenization, degassing, sterilization and aseptic filling are performed, so that the obtained soy milk is rich in nutrition and has a delicate taste, and the folic acid rich in it has the functions of preventing cancer and cardiovascular diseases, promoting cell metabolism and the like, and is an ideal health drink.

[0005] CN115997894A discloses a sprouted soybean rich in folic acid, a preparation method and a protein milk prepared by using the sprouted soybean, comprising the following steps: sterilization treatment: adding soybean seeds into a sodium hypochlorite aqueous solution for soaking and disinfection to obtain soybean mother grains, and then adding the soybean mother grains into water for soaking; germination: placing the soaked soybean mother grains in a germination machine, and spraying the soybean mother grains with a spraying liquid to make the soybean mother grains germinate, and obtaining sprouted soybeans rich in folic acid; wherein the spraying liquid includes water, sodium chloride, calcium chloride, and amino acids. The protein milk in this application has a high folic acid content and a good taste.

[0006] Folic acid has poor stability and is sensitive to light, so antioxidants such as sodium ascorbate are often added when extracting folic acid. However, after folic acid is enriched and processed into products, it is also necessary to pay attention to whether folic acid will decompose in the subsequent process. How to further improve its stability is a major issue that needs to be considered. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a soybean folate enrichment method and its application in folate-rich soymilk.

[0008] Under UV radiation, folic acid decomposes into 6-formylpterin (FPT) and p-aminobenzoylglutamate (PGA) by cleavage of the C9-N10 bridge; both undergo further changes, such as the formation of 6-carboxypterin (PCA) or the cleavage of PGA leading to the formation of p-aminobenzoic acid (PABA) and glutamate (GA). The photodecomposition of folic acid reduces the folic acid content of juice or other products stored in transparent bottles. The photostability of folic acid can be improved by forming complexes with proteins or β-cyclodextrin or by using biopolymer encapsulation by spray drying or electrospraying technology. In addition, the presence of low molecular weight antioxidants, such as ascorbic acid or catechins, can only reduce the loss of folic acid in fruits and vegetables to a limited extent. To further improve the stability, antioxidants with stronger antioxidant capacity are needed. Caffeic acid exhibits high antioxidant capacity due to its catechol structure, which is partly due to the hydrogen bonds between the ortho-phenolic hydroxyl groups stabilizing the aromatic radicals, and its photoproduct escin under UV irradiation has a higher free radical scavenging ability. However, the solubility of caffeic acid is very poor. It is difficult to dissolve in water at room temperature, but it is soluble in hot water. This defect will affect its application in many products. Therefore, the present invention provides a caffeic acid polymer nanoparticle for improving its water solubility. Adding it to soy milk can effectively protect folic acid from being photolyzed, thereby ensuring product quality. Polyethylene glycol monomethyl ether and 5-methyl-5-propynyloxycarbonyl-1,3-dioxane-2-one are used as functional monomers and lactide is subjected to ring-opening copolymerization under the catalysis of 4-dimethylaminopyridine. The obtained product is subjected to cycloaddition with 3-azidoprop-1-enylbenzene under the action of a catalyst, so that a cinnamyl group is grafted on the side chain. The obtained polymer has amphiphilicity because it uses polyethylene glycol monomethyl ether as a hydrophilic matrix and then grafts a hydrophobic group. The polymer is coated with caffeic acid to obtain caffeic acid polymer nanoparticles, which not only improves the water solubility, but also the cinnamyl group grafted on the side chain can also have a ππ stacking effect of aromatic groups with caffeic acid, thereby enhancing the stability of the load.

[0009] A soybean folic acid enrichment method is used in folic acid-rich soy milk, comprising the following steps:

[0010] S1. Soaking bright and complete soybean seeds in a 1 wt% sodium hypochlorite aqueous solution for 10 min for disinfection, washing and soaking in the soaking solution, soaking for 4 to 6 hours, and then soaking for germination. After germination for 24 to 36 hours, washing and grinding with water to obtain a homogenate;

[0011] S2. The homogenate is kept warm at 25-35° C. for 4-6 hours and then boiled to obtain cooked slurry, and 1-5wt% wheat germ powder, 2-5wt% white sugar, 0.001-0.1wt% caffeic acid polymer nanoparticles, 0.05-0.15wt% stabilizer, 0.1-0.3wt% sweetener, 0.1-0.4wt% thickener, 0.01-0.1wt% sucrose fatty acid ester, and 0.01-0.1wt% monoglyceride are added to prepare the mixture, and the mixture is homogenized and degassed, and then sterilized at 135-137° C. for 5-10 seconds and aseptically packaged to obtain the mixture.

[0012] Furthermore, the impregnation solution includes a mixture of water, sodium chloride, calcium chloride, p-aminobenzoic acid, and amino acids, wherein the sodium chloride is 30 mmol / L, the calcium chloride is 5 mmol / L, and the amino acid is 1 mmol / L; the p-aminobenzoic acid is 10 mmol / L; the amino acids include glutamic acid and glutamine, and the mass ratio of the two is 1:1.

[0013] Furthermore, the solid-liquid ratio of the soybean seeds to water-grinded pulp is 1:6-9 g / mL. Furthermore, the pulping is performed at 80-90° C. for 2-5 min.

[0014] Furthermore, the homogenization is carried out at 15-20 MPa, and then the pressure is increased to 30-40 MPa for secondary homogenization, and the homogenization temperature is 50-65°C.

[0015] Furthermore, the degassing is carried out at 65-75° C. and 0.05-0.10 MPa.

[0016] Furthermore, the stabilizer is sodium carboxymethyl cellulose.

[0017] Furthermore, the sweetener is xylitol.

[0018] Furthermore, the thickener is xanthan gum.

[0019] The method for preparing the caffeic acid polymer nanoparticles comprises the following steps:

[0020] X1. Mix 5-methyl-5-propynyloxycarbonyl-1,3-dioxane-2-one, lactide, polyethylene glycol monomethyl ether and 4-dimethylaminopyridine in a molar ratio of 1:5-6:0.2:0.1-0.5, and then vacuum dry. Heat to 120-130° C. to polymerize under an argon atmosphere. After 20-30 hours, perform polymerization. Add isopropanol for extraction, filter, dry and use in the next step.

[0021] X2. The product of the previous step and cuprous iodide are mixed in a molar ratio of 1:2-5 and dried in vacuo. A 0.3 mol / L tetrahydrofuran solution of 3-azidoprop-1-enylbenzene is added dropwise under an argon atmosphere. After the addition is complete, degassing is performed by bubbling with argon. N,N-diisopropylethylamine is added. The molar ratio of 3-azidoprop-1-enylbenzene to the product of the previous step and N,N-diisopropylethylamine is 1:3-4:15-16. The mixture is heated to 30-40°C and reacted for 20-30 hours. Tetrahydrofuran is added for dilution. The mixture is purified by column and concentrated to remove the solvent to obtain a residue. The residue is precipitated in a solution mixed with dichloromethane and hexane in a ratio of 1:1, filtered, and dried to obtain an amphiphilic copolymer.

[0022] X3. Dissolve caffeic acid in acetone, and then add an equal volume of amphiphilic copolymer acetone solution, the mass ratio of caffeic acid to amphiphilic copolymer is 1:10. Add the mixed solution into 6 to 8 times the volume of water, stir evenly and concentrate to remove acetone. Filter and freeze-dry to obtain caffeic acid polymer nanoparticles.

[0023] Preferably, the application of the soybean folic acid enrichment method in folic acid-rich soymilk comprises the following steps:

[0024] S1. Soybean seeds with bright color and complete grains are added to a 1wt% sodium hypochlorite aqueous solution for immersion and disinfection for 10 minutes, and then immersed in an immersion solution after washing, wherein the immersion solution includes a mixture of water, sodium chloride, calcium chloride, p-aminobenzoic acid, and amino acids, wherein the sodium chloride is 30mmol / L, the calcium chloride is 5mmol / L, and the molar concentration of amino acids is 1mmol / L; p-aminobenzoic acid is 10mmol / L; the amino acids include glutamic acid and glutamine, and the mass ratio of the two is 1:1. After completely immersing for 4 to 6 hours, soak and germinate, and after germination for 24 to 36 hours, wash and grind with water at a solid-liquid ratio of 1:6 to 9g / mL to obtain a homogenate;

[0025] S2. The homogenate is kept at 25-35° C. for 4-6 hours, then boiled at 80-90° C. for 2-5 minutes to obtain a cooked slurry, and 1-5 wt% of wheat germ powder, 2-5 wt% of white sugar, 0.001-0.1 wt% of caffeic acid polymer nanoparticles, 0.05-0.15 wt% of sodium carboxymethyl cellulose, 0.1-0.3 wt% of xylitol, 0.1-0.4 wt% of xanthan gum, 0.01-0.1 wt% of sucrose fatty acid ester, and 0.01-0.1 wt% of monoglyceride are added for preparation. After preparation, homogenization is performed at 15-20 MPa, and then the pressure is increased to 30-40 MPa for secondary homogenization at a homogenization temperature of 50-65° C. The mixture is degassed at 65-75° C. and 0.05-0.10 MPa, and then sterilized at 135-137° C. for 5-10 seconds and aseptically packaged to obtain the product.

[0026] Beneficial effects of the present invention:

[0027] 1. Compared with the prior art, a caffeic acid polymer nanoparticle is provided to improve the water solubility of caffeic acid. Adding the caffeic acid polymer nanoparticle to soymilk can effectively protect folic acid from being decomposed by light, thereby ensuring product quality.

[0028] 2. The present invention adopts plant biotransformation and processing technology. After soybeans are selected, sterilized and cleaned, substrates and hypertonic substances required for synthesizing folic acid are added to the soybean soaking liquid, and the conditions such as the temperature of the soybean germination environment are regulated to activate and improve the activity of folic acid synthase in the sprouted soybeans, thereby promoting the enrichment of folic acid in soybean seeds. The soybeans are homogenized after germination for 24 to 36 hours. During the heat preservation process, the plant endogenous enzyme (folic acid synthase) in the homogenate continues to act on para-aminobenzoic acid (pABA), amino acids (glutamic acid, glutamine) and other substances added during the soybean soaking, thereby synthesizing more folic acid. Wheat germ, sweeteners, stabilizers, caffeic acid derivatives, etc. are added to the obtained homogenate, and after pulping, blending, homogenization and sterilization, a product with high folic acid content and good stability is obtained. DETAILED DESCRIPTION

[0029] 5-Methyl-5-propynyloxycarbonyl-1,3-dioxane-2-one, CAS number: 945841-51-0.

[0030] Polyethylene glycol monomethyl ether, Mw=5000.

[0031] 3-azidoprop-1-enylbenzene, CAS No.: 68340-12-5.

[0032] Wheat germ powder, 80-120 mesh, Xinghua Mingwang Food.

[0033] Sucrose fatty acid esters, model: SE-15, Jiangsu Shunying Biotechnology.

[0034] Example 1

[0035] A soybean folic acid enrichment method is used in folic acid-rich soy milk, comprising the following steps:

[0036] S1. Soybean seeds with bright color and complete grains are added to a 1wt% sodium hypochlorite aqueous solution for immersion and disinfection for 10 minutes, and then immersed in an immersion solution after washing, wherein the immersion solution includes a mixture of water, sodium chloride, calcium chloride, p-aminobenzoic acid, and amino acids, wherein the sodium chloride is 30mmol / L, the calcium chloride is 5mmol / L, the molar concentration of amino acids is 1mmol / L, and the p-aminobenzoic acid is 10mmol / L; the amino acids include glutamic acid and glutamine, and the mass ratio of the two is 1:1. After completely immersing for 6 hours, soak and germinate, and after germination for 30 hours, wash and grind with water at a solid-liquid ratio of 1:6g / mL to obtain a homogenate;

[0037] S2. Keep the homogenate at 30°C for 6h and then cook it at 85°C for 5min to obtain cooked slurry, add 3wt% wheat germ powder, 3wt% white sugar, 0.1wt% caffeic acid polymer nanoparticles, 0.1wt% sodium carboxymethyl cellulose, 0.2wt% xylitol, 0.2wt% xanthan gum, 0.05wt% sucrose fatty acid ester and 0.05wt% monoglyceride to prepare, homogenize at 20MPa after preparation, then increase the pressure to 35MPa, perform secondary homogenization at a homogenization temperature of 60°C, deaerate at 70°C and 0.07MPa, and then sterilize at 135°C for 8s and aseptically package to obtain the product.

[0038] The method for preparing the caffeic acid polymer nanoparticles comprises the following steps:

[0039] X1. Mix 5-methyl-5-propynyloxycarbonyl-1,3-dioxane-2-one, lactide, polyethylene glycol monomethyl ether and 4-dimethylaminopyridine in a molar ratio of 1:5:0.2:0.4, and then vacuum dry. Heat to 125°C and polymerize under an argon atmosphere. After 24 hours, the polymerization is resolved. Add isopropanol for extraction, filter, dry and use in the next step.

[0040] X2. The product of the previous step and cuprous iodide were mixed in a molar ratio of 1:4 and dried in vacuo. A 0.3 mol / L tetrahydrofuran solution of 3-azidoprop-1-enylbenzene was added dropwise under an argon atmosphere. After the addition was complete, the mixture was degassed by bubbling with argon. N,N-diisopropylethylamine was added. The molar ratio of 3-azidoprop-1-enylbenzene to the product of the previous step and N,N-diisopropylethylamine was 1:3.5:15.5. The mixture was heated to 35°C and reacted for 24 hours. Tetrahydrofuran was added for dilution. The mixture was purified by column and concentrated to remove the solvent to obtain a residue. The residue was precipitated in a solution of a 1:1 mixture of dichloromethane and hexane, filtered, and dried to obtain an amphiphilic copolymer.

[0041] X3. Dissolve caffeic acid in acetone at a concentration of 1 g / L, then add an equal volume of amphiphilic copolymer acetone solution at a concentration of 10 g / L, add the mixed solution into 6 times the volume of water, stir evenly and concentrate to remove acetone, filter and freeze-dry to obtain caffeic acid polymer nanoparticles.

[0042] Example 2

[0043] It is basically the same as Example 1, the only difference being that the solid-liquid ratio during refining in step S1 is 1:7 g / mL.

[0044] Example 3

[0045] It is basically the same as Example 1, the only difference being that the solid-liquid ratio during refining in step S1 is 1:8 g / mL.

[0046] Example 4

[0047] It is basically the same as Example 1, the only difference being that the solid-liquid ratio during refining in step S1 is 1:9 g / mL.

[0048] Comparative Example 1

[0049] The process is substantially the same as Example 1, except that 0.009 wt % of caffeic acid is added in step S2 instead of 0.1 wt % of caffeic acid polymer nanoparticles.

[0050] Comparative Example 2

[0051] The method is basically the same as Example 1, except that no caffeic acid polymer nanoparticles are added in step S2.

[0052] Comparative Example 3

[0053] The method is basically the same as Example 1, except that the homogenate is directly boiled without heat preservation in step S2.

[0054] Test Example 1

[0055] The folic acid content of the soymilk in each embodiment and control example after being stored for 0 days and placed in the open air for 60 days was measured by high performance liquid chromatography.

[0056] Table 1 Folic acid content in soy milk and storage conditions (Note: soy milk is stored at room temperature)

[0057] Experimental protocol Folic acid content after 0 days μg / mL Folic acid content after 60 days Example 1 58.6 54.3 Example 2 55.1 52.4 Example 3 52.2 49.4 Example 4 49.3 46.5 Comparative Example 1 56.7 38.3 Comparative Example 2 55.8 32.1 Comparative Example 3 45.6 41.8

[0058] From the difference between the embodiment and the control example 2, it can be seen that the effect of caffeic acid polymer nanoparticles on maintaining folic acid content is very significant. Since folic acid is a substance with poor light stability, its content gradually decreases under ultraviolet radiation over time, and caffeic acid, as an antioxidant, can inhibit its photodecomposition through antioxidant action. In the embodiment, caffeic acid is loaded in a polymer carrier to improve its water solubility, so that it can better play an antioxidant role in soy milk with water as the medium. Therefore, after 60 days, the folic acid content in the embodiment is much higher than that in the control examples 1-2. The folic acid content in the control example 1 is higher than that in the control example 2 after 60 days of storage. This may be because the photodecomposition product of caffeic acid can also play a certain antioxidant role, but the water solubility of caffeic acid is poor, so the maintenance effect of the folic acid content in the control example 1 is not as good as that in the embodiment. Compared with the embodiments 2-4, the solid-liquid ratio during refining is different in the embodiment 1. From the final folic acid content, it can be seen that the solid-liquid ratio in the embodiment 1 should be the best. In Control Example 3, the homogenate was boiled without being kept warm, resulting in a lower folic acid content than in Example 3. This may be because the plant endogenous enzyme (folate synthase) in the homogenate continued to act on para-aminobenzoic acid, amino acids and other substances added during soybean soaking during the insulation process, thereby synthesizing more folic acid.

[0059] Test Example 2

[0060] The nutritional components and microorganisms of the soymilk prepared in Example 1 were examined, and the results are shown in Table 2.

[0061] Table 2 Soymilk quality test

[0062]

[0063] Test Example 3

[0064] According to GB 15193.1-2014 National Food Safety Standard Food Safety Toxicology Evaluation Procedure, the first-stage acute toxicity test and the second-stage genetic toxicity test, the traditional teratogenicity test, and the 90-day oral toxicity test of the soymilk of the present invention were carried out. The results showed that the acute toxicity test results were non-toxic; the bone marrow cell micronucleus test, the mouse sperm teratogenicity test, and the 90-day oral toxicity test were all negative. The toxicology test results provide a basis for the edible safety of the soymilk of the present invention.

[0065] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. Application of a soybean folic acid enrichment method in folic acid-rich soymilk, characterized in that: The steps include: S1. Soak bright and complete soybean seeds in a 1 wt% sodium hypochlorite aqueous solution for 10 min for disinfection, wash and soak in the soaking solution, soak for 4 to 6 hours, and then soak for germination. After germination for 24 to 36 hours, wash and grind with water to obtain a homogenate; S2. The homogenate is kept warm at 25-35° C. for 4-6 hours and then boiled to obtain cooked slurry, and 1-5wt% wheat germ powder, 2-5wt% white sugar, 0.001-0.1wt% caffeic acid polymer nanoparticles, 0.05-0.15wt% stabilizer, 0.1-0.3wt% sweetener, 0.1-0.4wt% thickener, 0.01-0.1wt% sucrose fatty acid ester, and 0.01-0.1wt% monoglyceride are added to prepare the mixture, and the mixture is homogenized and degassed, and then sterilized at high temperature and aseptically packaged to obtain the product.

2. The use of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soymilk, characterized in that: The impregnation solution includes a mixture of water, sodium chloride, calcium chloride, p-aminobenzoic acid, and amino acids, wherein the sodium chloride is 30 mmol / L, the calcium chloride is 5 mmol / L, the amino acid is 1 mmol / L; the p-aminobenzoic acid is 10 mmol / L; the amino acids include glutamic acid and glutamine, and the mass ratio of the two is 1:

1.

3. Application of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soymilk, characterized in that: The solid-liquid ratio of the soybean seeds after grinding with water is 1:6-9 g / mL.

4. The use of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soymilk, characterized in that: The slurry is boiled at 80-90° C. for 2-5 minutes.

5. Application of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soymilk, characterized in that: The homogenization is carried out at 15-20 MPa, and then the pressure is increased to 30-40 MPa for secondary homogenization, and the homogenization temperature is 50-65°C.

6. Application of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soymilk, characterized in that: The degassing is carried out at 65-75° C. and 0.05-0.10 MPa.

7. Application of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soymilk, characterized in that: The stabilizer is sodium carboxymethyl cellulose.

8. Application of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soymilk, characterized in that: The sweetener is xylitol.

9. Application of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soymilk, characterized in that: The thickener is xanthan gum.

10. Use of the soybean folic acid enrichment method according to claim 1 in folic acid-rich soy milk, characterized in that: The method for preparing the caffeic acid polymer nanoparticles comprises the following steps: X1. Mix 5-methyl-5-propynyloxycarbonyl-1,3-dioxane-2-one, lactide, polyethylene glycol monomethyl ether and 4-dimethylaminopyridine in a molar ratio of 1:5-6:0.2:0.1-0.5, and then vacuum dry. Heat to 120-130° C. to polymerize under an argon atmosphere. After 20-30 hours, perform polymerization. Add isopropanol for extraction, filter, dry and use in the next step. X2. The product of the previous step and cuprous iodide are mixed in a molar ratio of 1:2-5 and dried in vacuo. A 0.3 mol / L tetrahydrofuran solution of 3-azidoprop-1-enylbenzene is added dropwise under an argon atmosphere. After the addition is complete, degassing is performed by bubbling with argon. N,N-diisopropylethylamine is added, and the molar ratio of 3-azidoprop-1-enylbenzene to the product of the previous step and N,N-diisopropylethylamine is 1:3-4:15-16. The mixture is heated to 30-40°C and reacted for 20-30 hours. Tetrahydrofuran is added for dilution, and then the mixture is purified by column and concentrated to remove the solvent to obtain a residue. The residue is precipitated in a solution of a 1:1 mixture of dichloromethane and hexane, filtered, and dried to obtain an amphiphilic copolymer. X3. Dissolve caffeic acid in acetone, and then add an equal volume of amphiphilic copolymer acetone solution, the mass ratio of caffeic acid to amphiphilic copolymer is 1:

10. Add the mixed solution into 6 to 8 times the volume of water, stir evenly and concentrate to remove acetone. After filtering and freeze-drying, obtain caffeic acid polymer nanoparticles.

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