High-speed counter-current chromatography assisted water extraction process of theaflavins

Abstract

The application relates to the technical field of plant extraction, and provides a high-speed counter-current chromatography assisted water extraction process of teaflavin, which comprises the following steps: washing, drying and crushing tea leaves to obtain tea leaf powder; mixing the tea leaf powder, distilled water and microencapsulated vitamin C, heating and reacting, hotly filtering, cooling and obtaining a crude extract; extracting the crude extract, rotary evaporating, freeze-drying and obtaining a crude extract; separating the crude extract by using modified adsorption resin to obtain crude teaflavin; and separating the crude teaflavin by using high-speed counter-current chromatography to obtain teaflavin. In the extraction process, the microencapsulated vitamin C is added to promote the purification of teaflavin, and column chromatography separation technology and high-speed counter-current chromatography separation technology are used for secondary purification treatment, so that the obtained teaflavin is high in purity; meanwhile, the extraction process has the advantages of high extraction efficiency and high safety.

Description

Technical Field

[0001] This invention belongs to the field of plant extraction technology, specifically relating to a high-speed countercurrent chromatography-assisted water extraction process for theaflavins. Background Technology

[0002] Theaflavins are important active ingredients in tea, possessing various health benefits such as regulating blood lipids and providing antioxidant effects. Traditional extraction methods for theaflavins, such as solvent extraction and ultrasound-assisted extraction, often suffer from low extraction efficiency, high costs, and environmental pollution. Therefore, developing novel and efficient extraction technologies is of great significance.

[0003] High-speed countercurrent chromatography (HSCCC) is a novel liquid-liquid partition chromatography technique that separates samples based on their different partition coefficients between two immiscible solvents. HSCCC is simple to operate, highly efficient, requires no solid support, and has a wide range of applications, making it particularly suitable for the separation and purification of natural products. Using water extraction before HSCCC can improve the separation efficiency of subsequent HSCCC. Although some patented technologies exist for theaflavins extraction, most methods still require improvement in extraction efficiency, purity, cost control, and environmental protection.

[0004] Chinese patent CN 101081844 B discloses a method for the large-scale separation and preparation of four high-purity theaflavin monomers from black tea extract. This method combines gel column chromatography and high-speed countercurrent chromatography (HSCLC), leveraging the large-volume preparation capacity of gel column chromatography with the high separation efficiency of HSCLC. This complementary approach allows for the separation of the four main theaflavin monomers from black tea extract. This method can be used to separate tens of grams of high-purity theaflavin monomers from crude theaflavin extract, achieving a purity of over 97%. However, despite the high purity of the products obtained, this method suffers from high purification costs and low purification efficiency due to the low content of theaflavins in tea leaves.

[0005] Therefore, there is an urgent need to develop a high-speed countercurrent chromatography-assisted water extraction process for theaflavins, which can improve extraction efficiency, reduce costs, and reduce environmental pollution while ensuring high purity of theaflavins. Summary of the Invention

[0006] To address the existing technical problems, the present invention aims to provide a high-speed countercurrent chromatography-assisted water extraction process for theaflavins. This invention incorporates microencapsulated vitamin C during the extraction process to promote the purification of theaflavins, and further purifies them using column chromatography and high-speed countercurrent chromatography, resulting in high-purity theaflavins. Furthermore, this extraction process offers advantages such as high extraction efficiency and high safety.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a high-speed countercurrent chromatography-assisted water extraction process for theaflavins, comprising the following steps:

[0009] S1. Wash, dry, and crush the tea leaves to obtain tea powder;

[0010] S2. Mix the tea powder, distilled water, and microencapsulated vitamin C obtained in step S1, heat to 65-85℃, stir and react for 1-2 hours, filter while hot, cool, and obtain crude extract.

[0011] S3. Extract the crude extract obtained in step S2, rotary evaporate, and freeze dry to obtain the crude extract;

[0012] S4. The crude extract obtained in step S3 is separated using a modified adsorption resin to obtain crude theaflavins;

[0013] S5. The crude theaflavins obtained in step S4 are separated by high-speed countercurrent chromatography to obtain theaflavins.

[0014] The reaction mechanism and function of this invention are as follows:

[0015] 1. Vitamin C, as a water-soluble antioxidant, has been widely used in pharmaceuticals, food, and animal feed. However, due to its unstable chemical properties, it is easily affected by factors such as metal ions, light, high temperature, and acidity / alkalinity, losing its physiological activity and thus its antioxidant capacity. This limits the scope of use of vitamin C.

[0016] On the one hand, this invention uses vitamin C ethyl ether and azelaic acid to synthesize a novel vitamin C derivative with high antioxidant activity, and its antioxidant effect is significantly better than that of vitamin C. On the other hand, this invention uses paraffin and polyethylene glycol to encapsulate the vitamin C derivative, further limiting the ratio of paraffin, polyethylene glycol, and vitamin C derivative, thereby improving the encapsulation efficiency. During the extraction of theaflavins, when the system is heated, the paraffin begins to dissolve, and the vitamin C derivative in the microencapsulated vitamin C is slowly released, exerting an antioxidant effect, thereby improving the extraction rate of theaflavins in the crude extract.

[0017] 2. Macroporous adsorption resins possess screening capabilities due to their van der Waals forces, hydrogen bonds, network structure, and high specific surface area. Therefore, they are widely used in the pharmaceutical field and are an effective method for extracting water-soluble active ingredients from refined traditional Chinese medicines.

[0018] The modified adsorption resin provided by this invention has a simple preparation process and mild reaction conditions. Copolymerization of p-bromostyrene with hydrophilic monomers such as polyethylene glycol monomethyl ether methacrylate increases the hydrophilicity of the modified adsorption resin. After forming spherical resin, the introduction of anhydrous aluminum chloride and hydroxyprolyl chloride not only enhances the interactions such as hydrogen bonding, electrostatics, and van der Waals forces, but also forms mesopores in the spherical resin, effectively increasing the specific surface area of ​​the spherical resin, enhancing the adsorption performance, and thus improving the purity of theaflavins.

[0019] In some embodiments, the method for preparing microencapsulated vitamin C in step S2 includes the following steps:

[0020] A1. Mix vitamin C ethyl ether, azelaic acid, and tert-amyl alcohol, stir, heat to 40-50℃, add lipase, keep warm and shake for 20-30 hours, distill under reduced pressure, wash, and dry to obtain vitamin C derivative.

[0021] A2. Mix polyethylene glycol and methanol, heat to 75-85℃, stir and reflux to obtain a polyethylene glycol solution;

[0022] A3. Melt paraffin by heating it to 70-80℃, add the vitamin C derivative obtained in step A1, and add the polyethylene glycol solution obtained in step A2 while stirring. Keep the reaction at this temperature for 0.5-1.5h, cool, filter, wash with methanol, and dry to obtain microencapsulated vitamin C.

[0023] In some embodiments, the molar ratio of vitamin C ethyl ether and azelaic acid in step A1 is 1:(1.05-1.2).

[0024] In some embodiments, the mass ratio of paraffin, polyethylene glycol in the polyethylene glycol solution, and vitamin C derivative in step A3 is 1:(1.2-1.8):(0.9-1.2).

[0025] In some embodiments, the mass ratio of tea leaves, distilled water, and microencapsulated vitamin C in step S2 is 1:(20-40):(0.01-0.04).

[0026] In some embodiments, the method for preparing the modified adsorption resin in step S4 includes the following steps:

[0027] B1. Mix p-chlorostyrene and hydrazine hydrate, heat to 60-80℃, reflux the reaction, then perform column chromatography, wash, and dry to obtain hydrazine-containing styrene;

[0028] B2. Mix p-bromostyrene, polyethylene glycol monomethyl ether methacrylate, divinylbenzene and the hydrazine-containing styrene obtained in step B1, add an initiator, stir, add isopropanol, stir, and obtain the reaction mixture;

[0029] B3. Mix carbomer and water, heat to 45-55℃, stir, add sodium chloride, stir, cool, then add the reaction mixture obtained in step B2, and heat while stirring until spherical resin is formed.

[0030] B4. Wash and dry the spherical resin obtained in step B3, add acetone to swell, add anhydrous aluminum chloride and hydroxyprolyl chloride, react in an ice bath for 0.5-1 h, reflux for 20-30 h, cool and quench with crushed ice, filter, wash, extract with anhydrous ethanol, wash, dry to obtain the modified adsorption resin.

[0031] In some embodiments, the mass ratio of p-bromostyrene, polyethylene glycol monomethyl ether methacrylate, divinylbenzene and hydrazine-containing styrene in step B2 is (5-7.5):(2.5-4):1:(1.5-2.5).

[0032] In some embodiments, the mass ratio of the spherical resin to hydroxyprolyl chloride in step B4 is 1:(1.05-1.2).

[0033] In some embodiments, the solvent system for high-speed countercurrent chromatography separation in step S5 is: ethyl acetate-methanol-water-n-hexane-glacial acetic acid.

[0034] In some embodiments, the purity of theaflavins obtained by the extraction process is not less than 98%.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. In this invention, microencapsulated vitamin C is added during the extraction process to promote the purification of theaflavins, and the theaflavins are further purified using column chromatography and high-speed countercurrent chromatography, resulting in high purity theaflavins. At the same time, this extraction process has the advantages of high extraction efficiency and high safety.

[0037] 2. This invention synthesizes microencapsulated vitamin C. On the one hand, vitamin C derivatives enhance antioxidant activity; on the other hand, the applicant uses paraffin and polyethylene glycol to encapsulate the vitamin C derivatives, improving the encapsulation rate. During the extraction of theaflavins, when the system is heated, the paraffin begins to dissolve, and the vitamin C derivatives in the microencapsulated vitamin C are slowly released, exerting an antioxidant effect and thus improving the extraction rate of theaflavins in the crude extract.

[0038] 3. The modified adsorption resin provided by this invention has good hydrophilicity, which can effectively increase the specific surface area of ​​the resin microspheres, enhance the adsorption performance of the modified adsorption resin, and thus improve the purity of theaflavins.

[0039] 4. This invention can shorten the extraction time and increase the extraction rate by using column chromatography and high-speed countercurrent chromatography. At the same time, this extraction process further improves the extraction efficiency by optimizing extraction conditions, such as temperature, solvent type, and additives. Detailed Implementation

[0040] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0041] Theaflavins were extracted according to the proportions and processes of the raw materials specified in the following examples and comparative examples.

[0042] To facilitate implementation of this invention by those skilled in the art, the manufacturers of some raw materials for the embodiments and comparative examples are described below:

[0043] Polyethylene glycol monomethyl ether methacrylate: purchased from Zhongshan Dixin Chemical Co., Ltd.;

[0044] Polyethylene glycol: purchased from Haian Petrochemical Plant in Jiangsu Province, model number PEG-400;

[0045] Lipase: Purchased from Hebei Jiuyu Biotechnology Co., Ltd., enzyme activity 30000 cfu / g;

[0046] The paraffin wax is edible paraffin wax;

[0047] Unless otherwise specified, all other raw materials can be purchased from the market.

[0048] Preparation Example 1

[0049] The preparation method of microencapsulated vitamin C-1 includes the following steps:

[0050] A1. Mix 20.4g vitamin C ethyl ether, 20.7g azelaic acid, and 300ml tert-amyl alcohol, stir for 30min, heat to 45℃, add 3g lipase, keep warm and shake for 24h, distill under reduced pressure, wash once with ethyl acetate (v / v) and deionized water at 3℃, filter, wash three times with deionized water, and dry under vacuum at 50℃ for 6h to obtain vitamin C derivative;

[0051] A2. Mix 20g PEG-400 and 380ml methanol, heat to 80℃, stir and reflux for 3h to obtain a polyethylene glycol solution;

[0052] A3. Melt 10g of edible paraffin at 75℃, add 10g of vitamin C derivative obtained in step S1, and add 240.5g of polyethylene glycol solution while stirring. Keep the reaction at 800r / min for 1h, cool to room temperature, filter, wash twice with methanol, and air dry to constant weight to obtain microencapsulated vitamin C-1.

[0053] Preparation Example 2

[0054] The preparation method of microencapsulated vitamin C-2 is the same as that in preparation example 1, except that the amount of azelaic acid added in step A1 is 15.05g.

[0055] Preparation Example 3

[0056] The preparation method of microencapsulated vitamin C-3 is the same as that in preparation example 1, except that the amount of edible paraffin added in step A3 is 7.6g.

[0057] Preparation Example 4

[0058] The preparation method of microencapsulated vitamin C-4 is the same as that in Preparation Example 1, except that the amount of polyethylene glycol solution added in step A3 is 320.6g.

[0059] Preparation Example 5

[0060] The preparation method of hydroxyprolyl chloride is as follows:

[0061] 300g of hydroxyproline was mixed with 720ml of thionyl chloride in an ice bath at 0℃, heated to 55℃ and reacted for 16h. After dissolving in 2000ml of acetone, the mixture was filtered and rotary evaporated to obtain hydroxyproline chloride.

[0062] Preparation Example 6

[0063] The preparation method of modified adsorption resin-1 includes the following steps:

[0064] B1. Mix 25g of p-chlorostyrene, 10g of hydrazine hydrate and 350ml of anhydrous ethanol, heat to 70℃, reflux for 3h, then column chromatography, wash 3 times with anhydrous ethanol, dry at 80℃ to constant weight to obtain hydrazine-containing styrene.

[0065] B2. Mix 30g of p-bromostyrene, 15g of polyethylene glycol monomethyl ether methacrylate, 5g of divinylbenzene and 10g of hydrazine-containing styrene obtained in step B1, add 3g of benzoyl peroxide, stir for 2h, add 5g of isopropanol, stir for 1h to obtain the reaction mixture;

[0066] B3. Mix 1.5g carbomer and 300ml water, heat to 50℃, stir for 3h, add 1.5g sodium chloride, stir for 1h, cool to room temperature, then add the reaction mixture obtained in step B2, stir and heat at a temperature not exceeding 80℃ until spherical resin is formed.

[0067] B4. Wash the 25g spherical resin obtained in step B3 with deionized water four times, dry it at 70℃ to constant weight, add 400ml acetone to swell for 12h, add 5g anhydrous aluminum chloride and 26.25g hydroxyprolyl chloride, react in an ice bath at 3℃ for 0.5h, reflux for 24h, cool to room temperature, add 50g crushed ice to quench, filter, wash once with anhydrous ethanol, then wash with deionized water until neutral, extract with anhydrous ethanol for 12h, wash three times with deionized water, dry at 70℃ to constant weight to obtain modified adsorption resin-1.

[0068] Preparation Example 7

[0069] The modified adsorption resin-2 was prepared in the same way as in Preparation Example 6, except that the amount of hydrazine-containing styrene added was 6.5g.

[0070] Preparation Example 8

[0071] The modified adsorption resin-3 was prepared in the same way as in Preparation Example 6, except that the amount of hydroxyprolyl chloride added was 21.25 g.

[0072] Example 1

[0073] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins includes the following steps:

[0074] S1. Wash the tea leaves, dry them at 40℃ to constant weight, and crush them to obtain tea powder;

[0075] S2. Mix 100g of tea powder obtained in step S1, 3kg of distilled water, and 105g of microencapsulated vitamin C-1, heat to 75℃, stir and react for 1.5h, filter while hot, and cool to room temperature to obtain crude extract.

[0076] S3. The crude extract obtained in step S2 is first extracted with chloroform, the upper phase is then extracted with ethyl acetate, the upper phase is then extracted with 2.5wt% sodium bicarbonate aqueous solution, the upper phase is retained, the mixture is rotary evaporated, and freeze-dried at -40℃ for 18h to obtain the crude extract.

[0077] S4. The crude extract obtained in step S3 is separated using modified adsorption resin-1 to obtain crude theaflavins;

[0078] S5. The crude theaflavins obtained in step S4 are separated by high-speed countercurrent chromatography. The solvent system is ethyl acetate-methanol-water-n-hexane-glacial acetic acid with a volume ratio of 3:1:1:2 to obtain theaflavins.

[0079] Example 2

[0080] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins includes the following steps:

[0081] S1. Wash the tea leaves, dry them at 40℃ to constant weight, and crush them to obtain tea powder;

[0082] S2. Mix 100g of tea leaves, 2kg of distilled water and 90g of microencapsulated vitamin C-1 obtained in step S1, heat to 65℃, stir and react for 2h, filter while hot, cool to room temperature to obtain crude extract;

[0083] S3. The crude extract obtained in step S2 is first extracted with chloroform, the upper phase is then extracted with ethyl acetate, the upper phase is then extracted with 2wt% sodium bicarbonate aqueous solution, the upper phase is retained, the mixture is rotary evaporated, and freeze-dried at -40℃ for 18h to obtain the crude extract.

[0084] S4. The crude extract obtained in step S3 is separated using modified adsorption resin-1 to obtain crude theaflavins;

[0085] S5. The crude theaflavins obtained in step S4 are separated by high-speed countercurrent chromatography. The solvent system is ethyl acetate-methanol-water-n-hexane-glacial acetic acid with a volume ratio of 3:1:1:2 to obtain theaflavins.

[0086] Example 3

[0087] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins includes the following steps:

[0088] S1. Wash the tea leaves, dry them at 40℃ to constant weight, and crush them to obtain tea powder;

[0089] S2. Mix 100g of tea leaves, 4kg of distilled water and 120g of microencapsulated vitamin C-1 obtained in step S1, heat to 85℃, stir and react for 1 hour, filter while hot, cool to room temperature, and obtain crude extract.

[0090] S3. The crude extract obtained in step S2 is first extracted with chloroform, the upper phase is then extracted with ethyl acetate, the upper phase is then extracted with 3wt% sodium bicarbonate aqueous solution, the upper phase is retained, the mixture is rotary evaporated, and freeze-dried at -40℃ for 18h to obtain the crude extract.

[0091] S4. The crude extract obtained in step S3 is separated using modified adsorption resin-1 to obtain crude theaflavins;

[0092] S5. The crude theaflavins obtained in step S4 are separated by high-speed countercurrent chromatography. The solvent system is ethyl acetate-methanol-water-n-hexane-glacial acetic acid with a volume ratio of 3:1:1:2:1 to obtain theaflavins.

[0093] Example 4

[0094] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that the amount of microencapsulated vitamin C-1 added in step S2 is 80g.

[0095] Example 5

[0096] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that the solvent system in step S5 is ethyl acetate-methanol-water-n-hexane with a volume ratio of 3:1:1:2.

[0097] Example 6

[0098] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that in step S2, an equal amount of microencapsulated vitamin C-2 is used instead of microencapsulated vitamin C-1.

[0099] Example 7

[0100] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that in step S2, an equal amount of microencapsulated vitamin C-3 is used instead of microencapsulated vitamin C-1.

[0101] Example 8

[0102] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that in step S2, an equal amount of microencapsulated vitamin C-4 is used instead of microencapsulated vitamin C-1.

[0103] Example 9

[0104] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that in step S4, an equal amount of modified adsorption resin-2 is used instead of modified adsorption resin-1.

[0105] Example 10

[0106] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that in step S4, an equal amount of modified adsorption resin-3 is used instead of modified adsorption resin-1.

[0107] Comparative Example 1

[0108] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that in step S2, an equal amount of vitamin C is used to replace microencapsulated vitamin C-1.

[0109] Comparative Example 2

[0110] A high-speed countercurrent chromatography-assisted water extraction process for theaflavins is the same as in Example 1, except that in step S4, an equal amount of polyimide adsorption resin is used instead of modified adsorption resin-1.

[0111] Effect evaluation:

[0112] The theaflavins extracted in Examples 1-10 and Comparative Examples 1-2 were tested and analyzed. The specific results are shown in Table 1.

[0113] Performance testing:

[0114] The purity of theaflavins in the theaflavins extract was determined by HPLC. Mobile phase A was 2V% aqueous acetic acid solution, mobile phase B was acetonitrile-ethyl acetate solution with a volume ratio of 21:3, the flow rate was 0.9 ml / min, the column temperature was 40℃, and the detection wavelength was 280 nm.

[0115] Table 1

[0116] Example 1 99.3 Example 2 98.6 Example 3 98.9 Example 4 97.3 Example 5 97.6 Example 6 97.2 Example 7 96.4 Example 8 96.6 Example 9 95.8 Example 10 95.3 Comparative Example 1 94.6 Comparative Example 2 93.4

[0117] As shown in Table 1, the theaflavins obtained in Examples 1-3 have high purity and good application value.

[0118] Compared to Example 1, Example 4 changed the mass ratio of tea leaves, distilled water, and microencapsulated vitamin C, which is not conducive to the subsequent purification of theaflavins.

[0119] Compared to Example 1, Example 5 changed the solvent system for high-speed countercurrent chromatography separation, resulting in poor separation effect and hindering the separation and purification of theaflavins.

[0120] Compared to Example 1, Examples 6-8 show that in the preparation of microencapsulated vitamin C, Example 6 changed the molar ratio of vitamin C ethyl ether and azelaic acid, resulting in weakened antioxidant properties; Examples 7-8 changed the mass ratio of polyethylene glycol and vitamin C derivative in paraffin and polyethylene glycol solution, resulting in weakened sustained-release effect; Comparative Example 1 replaced microencapsulated vitamin C-1 with an equal amount of vitamin C, all of which affected the final antioxidant properties of vitamin C and were not conducive to the subsequent purification of theaflavins.

[0121] Compared to Example 1, Examples 9-10 show that in preparing the modified adsorption resin, Example 9 changed the mass ratio of p-bromostyrene, polyethylene glycol monomethyl ether methacrylate, divinylbenzene, and hydrazine-containing styrene, resulting in spherical resins with poor hydrophilicity. Example 10 changed the mass ratio of spherical resin and hydroxyprolyl chloride, weakening the interaction of van der Waals forces and hydrogen bonds. Comparative Example 2 replaced modified adsorption resin-1 with an equal amount of polyimide adsorption resin, which also affected the adsorption capacity of the modified adsorption resin and was not conducive to the purification of theaflavins.

[0122] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A high-speed countercurrent chromatography-assisted water extraction process for theaflavins, characterized in that, It includes the following steps: S1. Wash, dry, and crush the tea leaves to obtain tea powder; S2. Mix the tea powder, distilled water, and microencapsulated vitamin C obtained in step S1, heat to 65-85℃, stir and react for 1-2 hours, filter while hot, cool, and obtain crude extract. S3. Extract the crude extract obtained in step S2, rotary evaporate, and freeze dry to obtain the crude extract; S4. The crude extract obtained in step S3 is separated using a modified adsorption resin to obtain crude theaflavins; S5. The crude theaflavins obtained in step S4 are separated by high-speed countercurrent chromatography to obtain theaflavins.

2. The high-speed countercurrent chromatography-assisted water extraction process for theaflavins according to claim 1, characterized in that, The method for preparing microencapsulated vitamin C in step S2 includes the following steps: A1. Mix vitamin C ethyl ether, azelaic acid, and tert-amyl alcohol, stir, heat to 40-50℃, add lipase, keep warm and shake for 20-30 hours, distill under reduced pressure, wash, and dry to obtain vitamin C derivative. A2. Mix polyethylene glycol and methanol, heat to 75-85℃, stir and reflux to obtain a polyethylene glycol solution; A3. Melt paraffin by heating it to 70-80℃, add the vitamin C derivative obtained in step A1, and add the polyethylene glycol solution obtained in step A2 while stirring. Keep the reaction at this temperature for 0.5-1.5h, cool, filter, wash with methanol, and dry to obtain microencapsulated vitamin C.

3. The high-speed countercurrent chromatography-assisted water extraction process for theaflavins according to claim 2, characterized in that, The molar ratio of vitamin C ethyl ether and azelaic acid in step A1 is 1:(1.05-1.2).

4. The high-speed countercurrent chromatography-assisted water extraction process for theaflavins according to claim 2, characterized in that, In step A3, the mass ratio of paraffin, polyethylene glycol in the polyethylene glycol solution, and vitamin C derivative is 1:(1.2-1.8):(0.9-1.2).

5. The high-speed countercurrent chromatography-assisted water extraction process for theaflavins according to claim 1, characterized in that, The mass ratio of tea leaf fragments, distilled water, and microencapsulated vitamin C in step S2 is 1:(20-40):(0.01-0.04).

6. The high-speed countercurrent chromatography-assisted water extraction process for theaflavins according to claim 1, characterized in that, The preparation method of the modified adsorption resin in step S4 includes the following steps: B1. Mix p-chlorostyrene and hydrazine hydrate, heat to 60-80℃, reflux the reaction, then perform column chromatography, wash, and dry to obtain hydrazine-containing styrene; B2. Mix p-bromostyrene, polyethylene glycol monomethyl ether methacrylate, divinylbenzene and the hydrazine-containing styrene obtained in step B1, add an initiator, stir, add isopropanol, stir, and obtain the reaction mixture; B3. Mix carbomer and distilled water, heat to 45-55℃, stir, add sodium chloride, stir, cool, then add the reaction mixture obtained in step B2, and heat while stirring until spherical resin is formed. B4. Wash and dry the spherical resin obtained in step B3, add acetone to swell, add anhydrous aluminum chloride and hydroxyprolyl chloride, react in an ice bath for 0.5-1 h, reflux for 20-30 h, cool and quench with crushed ice, filter, wash, extract with anhydrous ethanol, wash, dry to obtain the modified adsorption resin.

7. The high-speed countercurrent chromatography-assisted water extraction process for theaflavins according to claim 6, characterized in that, The mass ratio of p-bromostyrene, polyethylene glycol monomethyl ether methacrylate, divinylbenzene and hydrazine-containing styrene in step B2 is (5-7.5):(2.5-4):1:(1.5-2.5).

8. The high-speed countercurrent chromatography-assisted water extraction process for theaflavins according to claim 6, characterized in that, The mass ratio of the spherical resin to hydroxyprolyl chloride in step B4 is 1:(1.05-1.2).

9. The high-speed countercurrent chromatography-assisted water extraction process for theaflavins according to claim 1, characterized in that, The solvent system for high-speed countercurrent chromatography separation in step S5 is: ethyl acetate-methanol-water-n-hexane-glacial acetic acid.

10. A high-speed countercurrent chromatography-assisted water extraction process according to any one of claims 1-9, characterized in that, The purity of theaflavins obtained by the extraction process is not less than 98%.