Green preparation process for efficient water extraction of theaflavin

Abstract

The invention relates to the technical field of plant extraction, in particular to a green preparation process for efficient water extraction of theaflavin, which comprises the following steps: S1, grinding black tea into black tea powder; s2, mixing the black tea powder in the step S1 with deionized water, heating to 70-80 DEG C, carrying out reflux stirring for 10-15 minutes, and filtering to obtain crude theaflavin filtrate; s3, eluting the theaflavin crude product filtrate in the step S2 by adopting a chromatographic column filled with modified macroporous adsorption resin to obtain a theaflavin diluent; and S4, concentrating and drying the theaflavin diluent in the step S3 under reduced pressure, adding chloroform and deionized water for extraction, combining water phases, evaporating to dryness to obtain a solid, adding ethanol, and concentrating and drying under reduced pressure to obtain theaflavin. The theaflavin extracted by the theaflavin preparation process is high in purity and high in extraction rate, meanwhile, the use amount of a solvent is small, and the theaflavin preparation process is environment-friendly.

Description

Technical Field

[0001] The invention relates to the technical field of plant extraction, and in particular to a green preparation process for highly efficient water-extracted theaflavins. Background Art

[0002] Theaflavins (TFs) are a class of compounds formed by enzymatic oxidation and polymerization of catechins during the fermentation of black tea. They have a unique benzophenone structure and a chemical formula of C 22 H 18 O 11 Theaflavins mainly include four monomers: theaflavin-3-gallate, theaflavin-3'-gallate, theaflavin-3,3'-digallate and theaflavin-3,3'-digallate.

[0003] Theaflavins have attracted much attention due to their powerful antioxidant, anti-inflammatory, and anti-cardiovascular disease pharmacological effects. Studies have shown that theaflavins can reduce the oxidation of low-density lipoprotein in the blood, thereby helping to prevent atherosclerosis. In addition, theaflavins also have multiple health benefits such as anti-tumor, anti-diabetes, anti-obesity, and neuroprotection. For example, theaflavins can help control blood sugar levels by regulating lipid metabolism and improving insulin sensitivity; in terms of anti-tumor, theaflavins can play an anti-cancer role by inhibiting tumor cell proliferation and promoting their apoptosis. These health benefits make theaflavins a hot spot for research and development of functional foods and drugs. Therefore, the extraction technology of theaflavins is also a hot research topic in the field of plant extraction today.

[0004] Traditional extraction methods of theaflavins mainly include hot water extraction, organic solvent extraction, etc. These methods can extract theaflavins to a certain extent, but there are problems such as low extraction efficiency, high cost, and environmental pollution. With the development of science and technology, modern extraction technology has made significant progress in improving the extraction efficiency of theaflavins, reducing costs and reducing environmental pollution. Modern extraction technology mainly includes water extraction technology, silica gel chromatography technology, gel chromatography technology, polyamide chromatography technology, high-performance countercurrent chromatography, macroporous resin technology, etc., as well as a combination of several methods. For example, CN101096693B discloses "a method for preparing theaflavins and thearubigins from fresh green tea". This method uses fresh green tea as raw material, ferments, extracts, concentrates, removes caffeine, and then elutes with ion exchange resin and adsorption resin to obtain theaflavins. Another example is the article "Study on the separation and purification of theaflavins by polyamide" in the journal "Food Science". The author used polyamide chromatography technology to explore its optimal separation conditions. For another example, CN101974581A discloses “a method for extracting and purifying theaflavins”, in which theaflavins are obtained by fermenting tea leaves and then using high-speed countercurrent chromatography and macroporous resin technology, thereby improving the purity of theaflavins.

[0005] Although there are various methods for extracting theaflavins, there is little research on the extraction of theaflavins with high purity and yield using water extraction combined with adsorption resin technology.

[0006] Therefore, it is urgent to develop a green preparation process that can improve the extraction rate and purity of theaflavins. Summary of the invention

[0007] The main purpose of the present invention is to provide a green preparation process for theaflavins by efficient water extraction. The theaflavins obtained by the preparation process have high purity and extraction rate, reduce the use of organic solvents, and are more environmentally friendly.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] The present invention provides a green preparation process for theaflavins by efficient water extraction, comprising the following steps:

[0010] S1, crushing black tea into black tea powder;

[0011] S2, mixing the black tea powder in step S1 with deionized water, heating to 70-80° C., refluxing and stirring for 10-15 min, and filtering to obtain a crude theaflavins filtrate;

[0012] S3, eluting the theaflavins crude product filtrate in step S2 using a chromatography column loaded with a modified macroporous adsorption resin to obtain a theaflavins dilution solution;

[0013] S4, the theaflavins diluted solution in step S3 is concentrated under reduced pressure and dried, chloroform and deionized water are added for extraction, the aqueous phases are combined and evaporated to dryness to obtain a solid, and then ethanol is added to concentrate under reduced pressure and dryness to obtain theaflavins.

[0014] The present application adopts water extraction and macroporous adsorption resin technology to synergistically prepare theaflavins. First, the black tea is crushed into powder and water extracted to obtain the crude theaflavins therein, and then the theaflavins dilution is obtained through a chromatography column of a modified macroporous adsorption resin. The applicant's research found that small molecules of impurities produced by hydrolysis of the modified macroporous adsorption resin will remain in the theaflavins dilution. The present application then extracts the theaflavins dilution with deionized water and chloroform to obtain pure theaflavins, and uses ethanol to remove excess chloroform to improve the bioavailability of theaflavins and reduce biological toxicity.

[0015] In some embodiments, in step S2, the solid-liquid mass ratio of the black tea powder to deionized water is 1:(40-60).

[0016] Preferably, in step S2, the solid-liquid mass ratio of the black tea powder to deionized water is 1:50.

[0017] In some embodiments, in step S3, the volume ratio of the mass of the modified macroporous adsorption resin to the crude theaflavin filtrate is (0.1-0.2):1.

[0018] Preferably, in step S3, the volume ratio of the mass of the modified macroporous adsorption resin to the crude theaflavin filtrate is 0.15:1.

[0019] The present application can prevent the increase in the amount of eluent used due to excessive adsorption resin and serious impact on elution efficiency by regulating the volume ratio of the mass of the modified macroporous adsorption resin to the crude theaflavins filtrate. In addition, it can also prevent the poor adsorption effect of theaflavins when the adsorption resin is small and they are easily washed out by deionized water.

[0020] In some embodiments, in step S3, the elution method of the chromatography column is: first rinse the chromatography column with 10-15°C deionized water that is 3-4 times the mass of the modified macroporous adsorption resin, then rinse the chromatography column with 38-42°C 55-75wt% ethanol solution and collect the eluate to obtain theaflavin dilution solution.

[0021] Preferably, in step S3, the elution method of the chromatography column is: first rinse the chromatography column with 12°C deionized water with a mass that is 4 times the modified macroporous adsorption resin, then rinse the chromatography column with 40°C 65wt% ethanol solution and collect the eluate to obtain theaflavin dilution solution.

[0022] The specific elution method adopted in the present application can improve the yield of theaflavins. The reason may be that, firstly, the tea polysaccharides and other substances that cannot be adsorbed can be washed away with low-temperature deionized water, wherein the low-temperature washing can also prevent the ester groups in the modified macroporous adsorption resin from being hydrolyzed and desorbed, so that part of the theaflavins are washed out by the deionized water, thereby reducing the yield of theaflavins; in addition, the chromatography column is washed with an ethanol solution of appropriate temperature, which can hydrolyze the ester groups in the modified macroporous adsorption resin and increase the polarity of the modified macroporous adsorption resin. If the adsorption capacity of polar theaflavins in the modified macroporous adsorption resin with increased polarity is weakened, it is easier to be washed and desorbed, thereby preventing theaflavins from remaining in the adsorption resin and improving the yield of theaflavins.

[0023] In some embodiments, the method for preparing the modified macroporous adsorption resin comprises the following steps:

[0024] (1) mixing 3-butene-1-ol, styrene, divinylbenzene, an initiator and a porogen to obtain an oil phase;

[0025] (2) adding gelatin into water and heating it to 50-55° C. until the gelatin is dissolved to obtain an aqueous phase;

[0026] (3) mixing the oil phase in step (1) with the water phase in step (2), heating the mixture to 65-75° C. and stirring at the constant temperature for 3-6 hours, then heating the mixture to 85-87° C. and stirring at the constant temperature for 6-7 hours. After the reaction is completed, filtering is performed to obtain a crude macroporous adsorption resin precursor.

[0027] (4) adding the crude modified macroporous adsorption resin precursor in step (3) into deionized water, heating the mixture to 95-100° C. and stirring the mixture at a constant temperature for 30-60 min to obtain a modified macroporous adsorption resin precursor;

[0028] (5) The modified macroporous adsorption resin precursor in step (4) is mixed with benzoic acid and added to anhydrous ethanol, and then concentrated sulfuric acid is added. The temperature is then raised to 50-60° C. and stirred at a constant temperature for 16-18 hours. After the reaction is completed, the temperature is lowered to room temperature, filtered, and washed with ice water for 2-3 times to obtain a modified macroporous adsorption resin.

[0029] Commercially available macroporous adsorption resins have a certain adsorption capacity for theaflavins, but they have weak adsorption effects or low desorption rates, which results in the inability to obtain high-yield and pure theaflavins using macroporous adsorption resin technology.

[0030] The present application can greatly improve the yield and purity of theaflavins by subjecting the crude product of theaflavins extracted by water to a self-made modified macroporous adsorption resin. The reason may be that the modified macroporous adsorption resin is obtained by polymerizing 3-butene-1-ol, styrene, and divinylbenzene as monomers and then modifying the hydroxyl groups therein, wherein the modified macroporous adsorption resin contains a large number of phenyl groups and ester groups. During use, the phenyl groups in theaflavins can form π-π bonds with the phenyl groups in the modified macroporous adsorption resin, and the phenolic hydroxyl groups can form weak hydrogen bonds with the ester groups. The two bonding modes synergistically adsorb theaflavins in the modified macroporous adsorption resin. In the early stage of cold water washing, the presence of the benzene ring reduces the activity of the ester group, making it difficult for the ester group to be hydrolyzed in cold water, thereby ensuring the adsorption stability of theaflavins in the modified macroporous adsorption resin and reducing Less theaflavins loss improves the theaflavins yield; when the impurities in the crude theaflavins are removed, the modified macroporous adsorption resin is rinsed with hot ethanol solution, the increase in temperature increases the activity of the ester group, and a hydrolysis reaction occurs in water to cause the phenyl group to fall off the modified macroporous adsorption resin, and the adsorption capacity of theaflavins is greatly weakened, so that it is removed by ethanol rinsing, thereby improving the desorption efficiency of the modified macroporous adsorption resin. In addition, the public paper "Theaflavins Purification Process and Study on Inhibition of Tooth Erosion Caused by Carbonated Beverages" proposed that "TFs is a weakly polar substance with a strong affinity with non-polar resins", and the modified macroporous adsorption resin of the present application will increase its polarity sharply after hydrolysis, making it easier to desorb theaflavins, thereby reducing the residue of theaflavins on the modified macroporous adsorption resin. In summary, the yield and purity of theaflavins are improved.

[0031] In some embodiments, the initiator is azobisisobutyronitrile or dibenzoyl peroxide.

[0032] In some embodiments, the porogen is toluene and / or liquid paraffin.

[0033] In some embodiments, in step (1), the mass ratio of 3-butene-1-ol, styrene and divinylbenzene is (0.1-0.13):1:(0.14-0.16).

[0034] Preferably, in step (1), the mass ratio of 3-butene-1-ol, styrene and divinylbenzene is 0.12:1:0.15.

[0035] The applicant can prevent the excessive ester content in the prepared modified macroporous adsorption resin from increasing the polarity of the adsorption resin and affecting the adsorption of theaflavins by adjusting the mass ratio of 3-butene-1-ol, styrene and divinylbenzene.

[0036] In some embodiments, in step (1), the amount of the initiator added is 0.6-0.8% of the total mass of 3-butene-1-ol, styrene and divinylbenzene.

[0037] Preferably, in step (1), the added amount of the initiator is 0.7% of the total mass of 3-butene-1-ol, styrene and divinylbenzene.

[0038] In some embodiments, in step (1), the amount of the porogen added is 45-50% of the total mass of 3-butene-1-ol, styrene and divinylbenzene.

[0039] In some embodiments, the mass of 3-butene-1-ol in step (1) is 0.25 to 0.3 times the mass of gelatin in step (2).

[0040] Preferably, the mass of 3-butene-1-ol in step (1) is 0.28 times the mass of gelatin in step (2).

[0041] In some embodiments, the molar ratio of benzoic acid in step (5) to 3-butene-1-ol in step (1) is 1:(1-1.2).

[0042] Preferably, the molar ratio of benzoic acid in step (5) to 3-butene-1-ol in step (1) is 1:(1-1.2).

[0043] The present application can convert the hydroxyl groups therein into ester groups by adjusting the molar ratio of benzoic acid to 3-butene-1-ol, which can reduce the polarity of the modified macroporous adsorption resin on the one hand and make the conversion of the hydroxyl groups therein more complete on the other hand.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The green preparation process of theaflavins of the present invention first grinds black tea into black tea powder to increase the specific surface area of ​​the black tea powder so that the theaflavins therein can be better released, then extracts the theaflavins therein by water extraction to remove impurities, then further purifies the theaflavins by a chromatography column of a modified macroporous adsorption resin, and finally extracts the theaflavins diluted solution to remove impurity compounds to obtain the finished theaflavins. The method has a high yield and purity of theaflavins, and at the same time uses a small amount of solvent, which is environmentally friendly.

[0046] (2) The modified macroporous adsorption resin of the present invention is obtained by polymerizing 3-butene-1-ol, styrene and divinylbenzene as monomers and then modifying the hydroxyl groups therein. The modified macroporous adsorption resin contains a large number of phenyl groups and ester groups. The phenyl groups can form π-π interactions with the phenyl groups in theaflavins, while the ester groups form hydrogen bonds with the phenolic hydroxyl groups in theaflavins. The two bonding modes synergistically allow theaflavins to be adsorbed in the modified macroporous adsorption resin, thereby improving the adsorption capacity of theaflavins and further improving the impurity removal rate.

[0047] (3) When using the modified macroporous adsorption resin of the present invention, it is first rinsed with cold water. Due to the presence of the benzene ring, the activity of the ester group is reduced, making it difficult for the ester group to be hydrolyzed in cold water, thereby ensuring the adsorption stability of theaflavins in the modified macroporous adsorption resin, thereby reducing the loss of theaflavins and increasing the yield of theaflavins; the modified macroporous adsorption resin is rinsed with hot ethanol solution. The increase in temperature increases the activity of the ester group, and a hydrolysis reaction occurs in water, causing the phenyl group to fall off the modified macroporous adsorption resin. The adsorption capacity of theaflavins is greatly weakened, so that it is removed by ethanol rinsing, thereby improving the desorption efficiency of the modified macroporous adsorption resin and increasing the yield of theaflavins. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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 are within the scope of protection of the present invention.

[0049] In the following preparation examples, embodiments and comparative examples, gelatin was purchased from Henan Mingang Food Ingredients Co., Ltd.; liquid paraffin was purchased from Shaanxi Panlong Yihai Pharmaceutical Co., Ltd.; and HZ-818 macroporous adsorption resin was purchased from Beijing Kangruina Biotechnology Co., Ltd.

[0050] The purity and content of theaflavins were detected by HPLC; the yield of theaflavins was calculated by the following formula:

[0051] Theaflavin yield (%) = W1 / W0 × 100%;

[0052] Where W1 is the amount of pure theaflavins in the purified theaflavins; W0 is the amount of pure theaflavins in black tea.

[0053] Preparation Example 1

[0054] The preparation method of the modified macroporous adsorption resin comprises the following steps:

[0055] (1) 60 g of 3-butene-1-ol, 500 g of styrene, 75 g of divinylbenzene, 4.5 g of azobisisobutyronitrile and 305 g of liquid paraffin were mixed to obtain an oil phase;

[0056] (2) Add 211 g of gelatin into 50 L of deionized water and heat to 52° C. until the gelatin is dissolved to obtain an aqueous phase;

[0057] (3) mixing the oil phase in step (1) with the water phase in step (2), heating to 70° C. and stirring at a constant temperature for 5 h, then heating to 86° C. and stirring at a constant temperature for 6 h. After the reaction is completed, filtering is performed to obtain a crude macroporous adsorption resin precursor;

[0058] (4) adding the crude modified macroporous adsorption resin precursor in step (3) to 10 L of deionized water, heating to 98° C. and stirring at constant temperature for 45 min, and filtering to obtain a modified macroporous adsorption resin precursor;

[0059] (5) The modified macroporous adsorption resin precursor in step (4) was mixed with 92 g of benzoic acid and added to 6 L of anhydrous ethanol, and then 381 g of 98 wt% concentrated sulfuric acid was added. The temperature was then raised to 55° C. and stirred at this temperature for 17 h. After the reaction was completed, the temperature was lowered to 27° C., filtered, and washed twice with ice water to obtain a modified macroporous adsorption resin.

[0060] Preparation Example 2

[0061] The preparation method of the modified macroporous adsorption resin is the same as that of Preparation Example 1, except that the added amount of 3-butene-1-ol is 75 g.

[0062] Preparation Example 3

[0063] The preparation method of the modified macroporous adsorption resin is the same as that of Preparation Example 1, except that the addition amount of 3-butene-1-ol is 40 g.

[0064] Preparation Example 4

[0065] The preparation method of the modified macroporous adsorption resin is the same as that of Preparation Example 1, except that the added amount of benzoic acid is 75 g.

[0066] Preparation Example 5

[0067] The preparation method of the modified macroporous adsorption resin is the same as that of Preparation Example 1, except that an equal molar amount of 4-methylvaleric acid is used instead of benzoic acid.

[0068] Example 1

[0069] A green preparation process for theaflavins by efficient water extraction, comprising the following steps:

[0070] S1. Grind 120g black tea into black tea powder;

[0071] S2, mixing 100 g of the black tea powder in step S1 with 5 L of deionized water, heating to 75° C., refluxing and stirring for 12 min, and filtering to obtain a crude theaflavins filtrate;

[0072] S3, eluting 5L of the crude theaflavins filtrate in step S2 with a chromatography column loaded with 750g of modified macroporous adsorption resin, first washing the chromatography column with 12°C deionized water of 3 times the mass of the modified macroporous adsorption resin, then washing the chromatography column with 40°C 65wt% ethanol solution and collecting the eluate to obtain the theaflavins dilution solution;

[0073] S4, the theaflavins diluted solution in step S3 is concentrated under reduced pressure and dried, chloroform and deionized water are added for extraction, the water phase is combined and evaporated to obtain a solid, and then ethanol with a volume of 8 times the mass of the solid is added to obtain theaflavins after reduced pressure concentration and drying. The purity of theaflavins obtained by testing is 85.26%, and the yield of theaflavins is 97.75%.

[0074] Wherein, the modified macroporous adsorption resin is prepared by Preparation Example 1.

[0075] Example 2

[0076] A green preparation process for theaflavins by efficient water extraction, comprising the following steps:

[0077] S1. Grind 120g black tea into black tea powder;

[0078] S2, mixing 100 g of the black tea powder prepared in step S1 with 4 L of deionized water, heating to 70° C., refluxing and stirring for 15 min, and filtering to obtain a filtrate of crude theaflavins;

[0079] S3, eluting the 4L crude theaflavins filtrate in step S2 with a chromatography column loaded with 400g of modified macroporous adsorption resin, first washing the chromatography column with 10°C deionized water of 3 times the mass of the modified macroporous adsorption resin, then washing the chromatography column with 38°C 55wt% ethanol solution and collecting the eluate to obtain theaflavins dilution solution;

[0080] S4, the theaflavins dilution in step S3 is concentrated and dried under reduced pressure, chloroform and deionized water are added for extraction, the water phase is combined and evaporated to obtain a solid, and then ethanol with a volume of 8 times the mass of the solid is added and concentrated and dried under reduced pressure to obtain theaflavins. The purity of theaflavins obtained by testing is 84.19%, and the yield of theaflavins is 96.38%.

[0081] Wherein, the modified macroporous adsorption resin is prepared by Preparation Example 1.

[0082] Example 3

[0083] A green preparation process for theaflavins by efficient water extraction, comprising the following steps:

[0084] S1. Grind 120g black tea into black tea powder;

[0085] S2, mixing 100 g of the black tea powder prepared in step S1 with 6 L of deionized water, heating to 80° C., refluxing and stirring for 10 min, and filtering to obtain a crude theaflavins filtrate;

[0086] S3, eluting the 6L crude theaflavins filtrate in step S2 with a chromatography column loaded with 1200g of modified macroporous adsorption resin, first washing the chromatography column with 15°C deionized water of 4 times the mass of the modified macroporous adsorption resin, then washing the chromatography column with 75wt% ethanol solution at 42°C and collecting the eluate to obtain theaflavins dilution solution;

[0087] S4, the theaflavins dilution in step S3 is concentrated under reduced pressure and dried, chloroform and deionized water are added for extraction, the aqueous phase is combined and evaporated to obtain a solid, and then ethanol with a volume of 8 times the mass of the solid is added to obtain theaflavins after reduced pressure concentration and drying. The purity of theaflavins obtained by testing is 85.39%, and the yield of theaflavins is 97.26%.

[0088] Wherein, the modified macroporous adsorption resin is prepared by Preparation Example 1.

[0089] Example 4

[0090] A green preparation process for theaflavin by efficient water extraction, the specific implementation method is the same as that of Example 1, except that the modified macroporous adsorption resin is prepared by Preparation Example 2. The purity of theaflavin obtained by testing is 85.12%, and the yield of theaflavin is 95.36%.

[0091] Example 5

[0092] A green preparation process for theaflavin by efficient water extraction, the specific implementation method is the same as that of Example 1, except that the modified macroporous adsorption resin is prepared by Preparation Example 3. The purity of theaflavin obtained by testing is 84.92%, and the yield of theaflavin is 93.75%.

[0093] Example 6

[0094] A green preparation process for theaflavin by efficient water extraction, the specific implementation method is the same as that of Example 1, except that the modified macroporous adsorption resin is prepared by Preparation Example 4. The purity of theaflavin obtained by testing is 85.31%, and the yield of theaflavin is 94.25%.

[0095] Example 7

[0096] A green preparation process for theaflavin by efficient water extraction, the specific implementation method is the same as that of Example 1, except that the modified macroporous adsorption resin is prepared by Preparation Example 5. The purity of theaflavin obtained by testing is 85.62%, and the yield of theaflavin is 92.37%.

[0097] Example 8

[0098] A green preparation process for theaflavin by efficient water extraction, the specific implementation is the same as that of Example 1, except that the chromatography column is rinsed with deionized water at 27° C. in step S3. The purity of theaflavin obtained by testing is 84.21%, and the yield of theaflavin is 91.71%.

[0099] Comparative Example 1

[0100] A green preparation process for theaflavin by efficient water extraction, the specific implementation method is the same as that of Example 1, except that the modified macroporous adsorption resin is replaced by HZ-818 macroporous adsorption resin of equal mass. The purity of theaflavin obtained by testing is 42.62%, and the yield of theaflavin is 59.62%.

[0101] Data Analysis:

[0102] According to the above results, it is found that the theaflavins extracted by the theaflavins preparation process of Examples 1 to 3 have high purity and high extraction rate; the theaflavins extracted by the theaflavins preparation process of Examples 4-8 have high purity but low extraction rate; the theaflavins extracted by the theaflavins preparation process of Comparative Example 1 have relatively low purity and extraction rate.

[0103] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A green preparation process for theaflavins by efficient water extraction, characterized in that: The steps include: S1, crushing black tea into black tea powder; S2, mixing the black tea powder in step S1 with deionized water, heating to 70-80°C, refluxing and stirring for 10-15 minutes, and filtering to obtain a crude theaflavins filtrate; S3, eluting the theaflavins crude product filtrate in step S2 using a chromatography column loaded with a modified macroporous adsorption resin to obtain a theaflavins dilution solution; S4, the theaflavins diluted solution in step S3 is concentrated under reduced pressure and dried, chloroform and deionized water are added for extraction, the aqueous phases are combined and evaporated to dryness to obtain a solid, and then ethanol is added to concentrate under reduced pressure and dryness to obtain theaflavins.

2. The green preparation process of theaflavins extracted by high efficiency water according to claim 1, characterized in that: In step S2, the solid-liquid mass ratio of the black tea powder to deionized water is 1:(40-60).

3. The green preparation process of theaflavins extracted by high efficiency water according to claim 1, characterized in that: In step S3, the volume ratio of the mass of the modified macroporous adsorption resin to the crude theaflavin filtrate is (0.1-0.2):

1.

4. The green preparation process of theaflavins extracted by high efficiency water according to claim 1, characterized in that: In step S3, the elution method of the chromatography column is: first rinse the chromatography column with 10-15°C deionized water with a mass of 3-4 times the modified macroporous adsorption resin, then rinse the chromatography column with 55-75wt% ethanol solution at 38-42°C and collect the eluate to obtain theaflavin dilution solution.

5. The green preparation process of theaflavins extracted by high efficiency water according to claim 1, characterized in that: The preparation method of the modified macroporous adsorption resin comprises the following steps: (1) mixing 3-butene-1-ol, styrene, divinylbenzene, an initiator and a porogen to obtain an oil phase; (2) adding gelatin into water and heating it to 50-55° C. until the gelatin is dissolved to obtain an aqueous phase; (3) mixing the oil phase in step (1) with the water phase in step (2), heating the mixture to 65-75° C. and stirring at the constant temperature for 3-6 hours, then heating the mixture to 85-87° C. and stirring at the constant temperature for 6-7 hours. After the reaction is completed, filtering is performed to obtain a crude macroporous adsorption resin precursor. (4) adding the crude modified macroporous adsorption resin precursor in step (3) into deionized water, heating the mixture to 95-100° C. and stirring the mixture at a constant temperature for 30-60 min to obtain a modified macroporous adsorption resin precursor; (5) The modified macroporous adsorption resin precursor in step (4) is mixed with benzoic acid and added to anhydrous methanol, and then concentrated sulfuric acid is added, followed by heating to 50-60° C. and stirring at a constant temperature for 16-18 hours. After the reaction is completed, the mixture is cooled to room temperature, filtered, and washed with ice water for 2-3 times to obtain a modified macroporous adsorption resin.

6. The green preparation process of theaflavins extracted by high efficiency water according to claim 5, characterized in that: In step (1), the mass ratio of 3-butene-1-ol, styrene and divinylbenzene is (0.1-0.13):1:(0.14-0.16).

7. The green preparation process of theaflavins extracted by high efficiency water according to claim 5, characterized in that: In step (1), the amount of the porogen added is 45-50% of the total mass of 3-butene-1-ol, styrene and divinylbenzene.

8. The green preparation process of theaflavins extracted by high efficiency water according to claim 5, characterized in that: In step (1), the added amount of the initiator is 0.6-0.8% of the total mass of 3-butene-1-ol, styrene and divinylbenzene.

9. The green preparation process of theaflavins extracted by high efficiency water according to claim 5, characterized in that: The mass of 3-butene-1-ol in step (1) is 0.25 to 0.3 times the mass of gelatin in step (2).

10. The green preparation process of theaflavins extracted by water according to claim 5, characterized in that: The molar ratio of benzoic acid in step (5) to 3-butene-1-ol in step (1) is 1:(1-1.2).