A method for improving stability of epigallocatechin gallate

Abstract

The present application provides a method for improving the stability of epigallocatechin gallate. The method for improving the stability of epigallocatechin gallate of the present application is to prepare water-oil amphiphilic seaweed fiber, and then perform high shear homogenization treatment with water and tea extract, so as to improve the stability of EGCG at different temperatures and pH values. The water-oil amphiphilic seaweed cellulose is obtained by modifying seaweed extract with wheat germ oil. The present application protects EGCG in tea extract by using water-oil amphiphilic seaweed cellulose, thereby improving the stability of EGCG at different temperatures and pH values. The tea extract can maintain stability and activity under different temperature and pH value treatment in the preparation of different products, thereby improving the application range of tea extract.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for improving the stability of epigallocatechin gallate. BACKGROUND

[0002] Epigallocatechin gallate (EGCG) is a tea polyphenol active ingredient extracted from green tea, which belongs to catechin. Because of its special stereochemical structure, EGCG has very strong antioxidant activity, anti-free radical DNA damage, anti-radiation and anti-ultraviolet properties, and can also prevent oil peroxidation and reduce the content of low-density cholesterol, ultra-low-density cholesterol and triglycerides in blood.

[0003] However, tea is easily affected by high temperature, light, humidity and pH during the traditional production process and storage conditions, and a series of complex chemical reactions occur in the contained chemical components. The stability of EGCG itself is poor, and it is easily affected by temperature, pH and other factors during tea beverage processing and storage, and undergoes degradation, oxidation and isomerization, thereby changing its original physiological activity. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to provide a method for improving the stability of epigallocatechin gallate. The water-oil amphiphilic seaweed cellulose prepared is subjected to high shear homogenization with water and tea extract, so as to improve the stability of EGCG at different temperatures and pH values.

[0005] To solve the above technical problems, the present application is implemented by the following technical solutions:

[0006] A preparation method of a cellulose water microdroplet EGCG emulsion, comprising adding tea extract and water-oil amphiphilic seaweed cellulose into water for high shear homogenization, fully fusing the two to obtain a primary emulsion, and then adding vegetable oil to the primary emulsion and continuing to homogenize, so that the components are fully fused.

[0007] The water-oil amphiphilic seaweed cellulose is obtained by modifying seaweed extract with wheat germ oil for completing lipophilic modification.

[0008] In the present application, the addition amount of tea extract is determined according to the solubility in water phase or oil phase and the concentration of EGCG. The concentrated crystallization of tea extract is rich in EGCG, and the mass / volume ratio of tea extract to water is (0.03-0.05):4-6 (m / v).

[0009] Preferably, the volume ratio of water-oil amphiphilic seaweed cellulose to water is 1:4-6 (v / v), preferably 1:5 (v / v).

[0010] Preferably, the volume ratio of the initial emulsion to the plant oil is 1:3-5 (v / v), preferably 1:4 (v / v).

[0011] Preferably, in the homogenization, the rotation speed of the homogenizer is 4000 r / min or above.

[0012] In the present application, the tea extract is rich in EGCG, and the extraction method of the tea extract can use any existing extraction method that can obtain a rich content of EGCG. As one preferred embodiment, the method for preparing the tea extract rich in EGCG is as follows:

[0013] (1) First soaking of tea: Put the tea into a mixed solution of glucose and fructose, first treat it under a negative pressure of 0.08-0.1 MPa for 20-30 min, then perform the first soaking under normal temperature and pressure, and then remove the filtrate by solid-liquid separation to obtain the tea after the first soaking; the first soaking is a liquid-solid extraction process, and the purpose is to remove impurities in the tea by negative pressure displacement. Under the negative pressure condition, the penetration and diffusion ability of the solvent to the tea is enhanced, so that the impurities in the tea can be dissolved out more quickly;

[0014] Preferably, in the first soaking, the mixed solution of glucose and fructose comprises 20-30% of glucose, 5-10% of fructose, and the balance of water.

[0015] Preferably, in the first soaking, the mass-to-volume ratio between the tea and the mixed solution of glucose and fructose is (0.5-1.5):(0.5-1.5).

[0016] Preferably, the time for the tea to be soaked once is 20-30 h.

[0017] (2) Second soaking of tea: Put the tea after the first soaking into water for the second soaking, so that the effective components in the tea are fully dissolved in the water, and then remove the tea by solid-liquid separation to obtain the tea extract rich in EGCG.

[0018] Preferably, in the second soaking, the mass-to-volume ratio between the tea and the water is (0.5-1.5):(5-15), the soaking temperature is 70-90℃, and the soaking time is 3-5 h.

[0019] (3) Concentration and crystallization of the tea extract: use a rotary evaporator to concentrate and crystallize the tea extract, wherein the reaction conditions are as follows: vacuum negative pressure 0.08-0.09 MPa, water bath temperature 60℃, and the rotation speed is adjusted according to the liquid boiling state, with the highest rotation speed being 12, and finally obtain the tea extract rich in EGCG.

[0020] The method for preparing the water-oil amphiphilic seaweed cellulose comprises the following steps:

[0021] (1) After the washed seaweed is dried, the seaweed is mixed with water to obtain a seaweed gel dispersion; preferably, the mass-to-volume ratio between the seaweed and water is 1:(20-40).

[0022] Since the red seaweed contains a high content of galactose sulfate (carrageenan), it is not necessary to add additional thickening agents and adhesives. In addition, the red seaweed contains a large amount of soluble dietary fiber or substances with the characteristics of water-soluble dietary fiber, which has the effects of reducing blood sugar and promoting digestion, thereby increasing the absorption of the wrapped substances (i.e. EGCG). In addition, the red seaweed is easy to obtain and has low cost. Therefore, the seaweed of the present application is preferably red seaweed.

[0023] (2) The seaweed gel dispersion is sequentially subjected to low-temperature stirring treatment at 4-8℃ and high-temperature film evaporation treatment at 75-85℃, and the film is removed to obtain a seaweed primary extract;

[0024] (3) The seaweed primary extract is treated with plant oil for completing the lipophilic modification in a double-cone rotary reactor for 24 hours, and the treatment temperature is 40-50℃. After the completion, the oil is removed (the plant oil in the upper layer of the mixture after the treatment in the double-cone rotary reactor is taken out, and then centrifugation is performed to complete the oil removal operation), to obtain the water-oil amphiphilic seaweed cellulose, i.e. a natural surfactant.

[0025] In the present application, the plant oil used to complete the lipophilic modification is wheat germ oil. Wheat germ oil is a nutrient-rich plant oil, and its components mainly include fatty acids, tocopherol (vitamin E), phytosterol and other bioactive substances. Among them, linoleic acid is the main component of the composition of fatty acids, accounting for 42-64.82%, such as the low gluten wheat germ oil extracted by supercritical CO2, the linoleic acid content can reach 58.23%. "When hydrophobic segments are added to hydrophilic polymer chains, amphiphilic copolymers are synthesized. In aqueous solution, amphiphilic molecules self-orient to achieve the minimum free energy state, and the hydrophobic segment is removed from the water environment. Therefore, polymer micelles with core / shell structure are formed. Because their hydrophobic domains are surrounded by a hydrophilic shell, they can serve as a reservoir for various hydrophobic drugs" (A. Martinez, Polysaccharide-Based Nanoparticles for Controlled Release Formulations, 2012, P202), the linoleic acid with the highest content in the wheat germ oil contains a hydrophobic group (with lipophilicity), and the alginate cellulose (a polysaccharide) contains a hydrophilic group. Mixing the two will form a hydrophilic-lipophilic copolymer. "Some long-chain fatty acids, such as caproic acid, linoleic acid, linolenic acid, palmitic acid or stearic acid, have been used to modify polysaccharides and obtain polymer micelles" (A. Martinez, Polysaccharide-Based Nanoparticles for Controlled Release Formulations, 2012, P202, paragraph 4), the present application utilizes the lipophilic hydrophobic group of wheat germ oil to mix with the hydrophilic group of polysaccharide to form a hydrophilic-lipophilic copolymer, and completes the lipophilic modification of alginate cellulose by wheat germ oil.

[0026] Based on the above, it can be known that the water-oil dual alginate cellulose can be used to improve the stability of EGCG in tea extract, including at least one of the temperature stability and pH stability of EGCG.

[0027] The beneficial effects of the above technical solutions of the present application are as follows:

[0028] The present application utilizes the water-oil dual alginate cellulose to protect the EGCG in the tea extract, thereby improving the stability of the EGCG at different temperatures and different pH values, so that the tea extract can maintain stability and activity under different temperature and pH treatment in the preparation of different products, thereby improving the application range of the tea extract. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a schematic diagram for the preparation process of the tea extract of Example 1.

[0030] Figure 2 Preparation flow chart of seaweed cellulose for example 2;

[0031] Figure 3 Preparation flow chart of cellulose water microdroplet EGCG emulsion;

[0032] Figure 4 Staining chart of cellulose water microdroplet EGCG emulsion for example 3;

[0033] Figure 5 Zeta potential analysis chart of cellulose water microdroplet EGCG emulsion for example 3;

[0034] Figure 6 Chart of EGCG content change of cellulose water microdroplet EGCG emulsion for example 3 at different temperatures;

[0035] Figure 7 Chart of EGCG content change of cellulose water microdroplet EGCG emulsion for example 3 at different pH values. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and advantages to be solved by the present application more clear, the following will be described in detail with specific examples.

[0037] The present application aims to improve the stability of EGCG, and thus proposes a cellulose water microdroplet EGCG emulsion, and the preparation method comprises adding tea extract and water-oil amphiphilic seaweed cellulose into water for high shear homogenization, fully mixing the two to obtain a primary emulsion, then adding vegetable oil into the primary emulsion and continuing homogenization, so as to fully mix the components.

[0038] The tea extract is rich in EGCG in the process of concentration and crystallization, and the mass-volume ratio (g / mL) of the tea extract to water is (0.03-0.05):(4-6).

[0039] The volume ratio (mL / mL) of the water-oil amphiphilic seaweed cellulose to water is 1:(4-6), and preferably 1:5; the volume ratio of the primary emulsion to the vegetable oil is 1:3-5, and preferably 1:4.

[0040] In the homogenization, the rotation speed of the homogenizer is 4000 r / min or above.

[0041] The method of the tea extract is as follows:

[0042] (1) The first tea leaf infusion: the tea leaf is put into the mixed solution of glucose and fructose, first treated under the negative pressure of 0.08-0.1 MPa for 20-30 min, then subjected to the first infusion under the normal temperature and pressure, and then the filtrate is removed by solid-liquid separation to obtain the tea leaf after the first infusion; the first infusion is a liquid-solid extraction process, and the purpose is to remove the impurities in the tea leaf by negative pressure replacement; under the negative pressure, the penetration and diffusion capacity of the solvent to the tea leaf are enhanced, and the impurities in the tea leaf can be dissolved more quickly;

[0043] In the first infusion, the mixed solution of glucose and fructose comprises 20-30% of glucose, 5-10% of fructose and the balance of water; the mass-to-volume ratio (kg / L) between the tea leaf and the mixed solution of glucose and fructose is (0.5-1.5):(0.5-1.5); and the infusion time is 20-30 h.

[0044] (2) The second tea leaf infusion: the tea leaf after the first infusion is put into water for the second infusion, so that the effective components in the tea leaf are fully dissolved in the water; the tea leaf is removed by solid-liquid separation to obtain the tea leaf infusion rich in EGCG. In the second infusion, the mass-to-volume ratio (kg / L) between the tea leaf and water is (0.5-1.5):(5-15), the infusion temperature is 70-90℃, and the infusion time is 3-5 h.

[0045] (3) Concentration and crystallization of the tea leaf infusion: the tea leaf infusion is subjected to concentration and crystallization by using a rotary evaporator, wherein the reaction conditions are as follows: vacuum negative pressure 0.08-0.09 MPa, water bath temperature 60℃, and the rotation speed is adjusted according to the liquid boiling state, and the highest rotation speed is 12; finally, the tea leaf extract rich in EGCG is obtained.

[0046] The preparation method of the water-oil amphiphilic seaweed cellulose comprises the following steps:

[0047] (1) The washed seaweed is dried and then mixed with water to obtain an alginate dispersion liquid; the mass-to-volume ratio (g / mL) between the seaweed and water is 1:(20-40).

[0048] Since the content of sulfuric acid galactose (carrageenan) in the red algae is high, it is not necessary to add additional thickening agent and adhesive; in addition, the red algae contains a large amount of soluble dietary fiber or substances with the characteristics of water-soluble dietary fiber, which has the effects of reducing blood sugar and promoting digestion, thereby increasing the absorption of the wrapped substances (i.e. EGCG); in addition, the red algae is easy to obtain and has low cost; therefore, the seaweed of the present application is preferably red algae.

[0049] (2) The alginate dispersion liquid is subjected to low-temperature stirring treatment at 4-8℃ and high-temperature film evaporation treatment at 75-85℃ in sequence, and then the film is removed to obtain an initial seaweed extract;

[0050] (3) The seaweed primary extract and the vegetable oil used for completing the lipophilic modification are treated in a double-cone rotary reactor for 24 hours at a treatment temperature of 40-50℃, and after the completion, the oil removal treatment is performed (the vegetable oil separated from the mixture in the double-cone rotary reactor after the treatment is taken out, and then the centrifugation is performed to complete the oil removal operation), and the seaweed cellulose with water-oil amphiphilicity, i.e. the natural surfactant, is obtained.

[0051] The tea leaves (or tea powder) involved in the present application are selected from Yunnan Lincang Diannqing.

[0052] Example 1

[0053] The preparation method of the tea leaf extract rich in EGCG comprises the following steps:

[0054] (1) First-time soaking of tea leaves: the tea leaves are put into a mixed solution of glucose and fructose, first treated under a negative pressure of 0.08-0.1 MPa for 20-30 min, then first-time soaked under normal temperature and pressure, and then solid-liquid separation is performed to remove the filtrate to obtain the tea leaves after the first-time soaking;

[0055] In the first-time soaking, the mixed solution of glucose and fructose comprises 25% of glucose, 8% of fructose and the rest of water; the mass-to-volume ratio between the tea leaves and the mixed solution of glucose and fructose is 1 kg: 1 L; the tea leaves are soaked for 25 h to sufficiently remove the impurities in the tea leaves.

[0056] (2) Second-time soaking of tea leaves: the tea leaves after the first-time soaking are put into clean water for second-time soaking to make the effective components in the tea leaves sufficiently dissolved in the water, and then solid-liquid separation is performed to remove the tea leaves to obtain the tea leaf soaking liquid rich in EGCG. In the second-time soaking, the mass-to-volume ratio between the tea leaves and the water is 1 kg: 10 L, the soaking temperature is 80℃, and the soaking time is 4 h;

[0057] (3) Concentration and crystallization of the tea leaf soaking liquid: a rotary evaporator is used to perform the concentration and crystallization of the tea leaf soaking liquid, wherein the reaction conditions are as follows: vacuum negative pressure of 0.08-0.09 MPa, water bath temperature of 60℃, and the rotation speed is adjusted according to the liquid boiling state, and the highest rotation speed is 12, and finally the tea leaf extract rich in EGCG is obtained.

[0058] Example 2

[0059] The preparation method of the seaweed cellulose with water-oil amphiphilicity comprises the following steps:

[0060] (1) The washed red algae are dried and then mixed with water to obtain an alginate dispersion liquid; the mass-to-volume ratio between the red algae and the water is 1 g: 30 mL.

[0061] (2) The algal glue dispersion liquid is subjected to low-temperature stirring treatment at 4-8℃ and high-temperature film evaporation treatment at 75-85℃ in sequence, and the film is peeled to obtain seaweed primary extract;

[0062] (3) The seaweed primary extract and wheat germ oil are treated in a double-cone rotary reactor for 24 hours, the treatment temperature is 40-50℃, after the treatment, the upper layer of the mixture in the double-cone rotary reactor is taken out, and then centrifugation is performed to complete the oil removal operation, and the water-oil amphiphilic seaweed cellulose, i.e. natural surfactant, is obtained.

[0063] Example 3

[0064] The preparation method of the cellulose water microdroplet EGCG emulsion includes the following steps:

[0065] (1) The tea leaf extract of Example 1 and the water-oil amphiphilic seaweed cellulose of Example 2 are added into water for high-shear homogenization, and the two are fully fused to obtain a primary emulsion;

[0066] (2) After the addition of wheat germ oil to the primary emulsion, homogenization is continued to fully fuse the components.

[0067] In this example, in step (1), the addition amount of tea leaf extract is 0.04g, the addition amount of water is 5mL, and the addition amount of water-oil amphiphilic seaweed cellulose is 1mL.

[0068] In step (2), 4 times the volume of the primary emulsion of plant oil is added to the primary emulsion obtained in step (1).

[0069] The rotation speed of the homogenizer used for homogenization is at least 4000 r / min.

[0070] The prepared product is dyed with rhodamine, and the results are shown in Figure 4 , which shows that the lipid (yellow) can indicate that the membrane is lipid, and the globular shape indicates that it is encapsulated.

[0071] Stability detection

[0072] ① 2g of the cellulose water microdroplet EGCG emulsion prepared in Example 3 is mixed with 50℃, 100mL of water, and is left to stand at room temperature for 30min, and then is filtered through a 0.45μm filter membrane, and the obtained liquid is the cellulose water microdroplet EGCG emulsion mixed liquid for testing.

[0073] ② 2g of tea powder is mixed with 50℃, 100mL of water, and is left to stand at room temperature for 30min, and then is filtered through a 0.45μm filter membrane, and the obtained liquid is the fresh tea leaf infusion for testing, which is used as a comparative example.

[0074] ③ Adjust pH with ammonia water and hydrochloric acid, and detect the content after 0, 1, 3, 7 days of placement respectively; adjust temperature by refrigerator and water bath, and detect the content after 0, 1, 7, 14 days of placement respectively.

[0075] The method for detecting the content of EGCG is reverse phase liquid chromatography, and the detection reagent includes: pure water, glacial acetic acid, methanol, EGCG standard;

[0076] The preparation method of EGCG standard is as follows: weigh 10.0 mg of EGCG standard substance, and add 3% glacial acetic acid solution to make up to 100 mL.

[0077] The specific steps of detecting the content of EGCG by reverse phase liquid chromatography are as follows: the peak area of EGCG detection of the example group and the comparative example group is obtained by liquid chromatography after being filtered by 0.45 μm filter membrane, and the content of EGCG in the sample is calculated according to the formula "standard EGCG peak area / standard EGCG concentration=sample EGCG peak area / sample EGCG concentration".

[0078] The liquid chromatography detection conditions are as follows: a 250mm×4.5mm stainless steel column filled with 5μm C18 bonded stationary phase is used; the mobile phase A is methanol, and the mobile phase B is 3% glacial acetic acid solution; the excitation wavelength is 280nm; the flow rate is set to 1.0mL / min; the column temperature is 40℃; and the injection amount is 10μL.

[0079] The gradient of the mobile phase of the reverse phase liquid chromatography is as follows:

[0080]

[0081] The formula for calculating the stability of EGCG under different conditions is as follows: the stability of EGCG on the Nth day (%)=(EGCG content on the Nth day / EGCG content on the 0th day)×100%.

[0082] Performance verification:

[0083] The cellulose water microdroplet EGCG emulsion obtained in Example 3 was subjected to Zeta potential analysis experiment, as shown in the table, the lowest potential values obtained by repeating the test for 3 times were-90.2mV, -94.5mV and-86.7mV, and the results showed that the emulsion had strong stability. Figure 5

[0084] Stability results

[0085] The temperature stability test results are as follows: Figure 6 ​As shown, long time storage of tea infusion at different temperatures, 4℃ and 25℃, resulted in the decrease and fluctuation of EGCG content in tea, which might be caused by degradation or transformation. However, the results showed that the cellulose water droplet EGCG emulsion could protect and stabilize EGCG, preventing its degradation and transformation.

[0086] The results of pH stability test are shown in Figure 6. Figure 7 As shown, in acidic environment (pH = 2 or 4), EGCG in both cellulose water droplet EGCG emulsion and tea infusion was relatively stable, and no significant decrease of EGCG was observed. In slightly neutral environment (pH = 6 or 7 or 8), the content of EGCG in tea infusion was significantly fluctuated and decreased, while the cellulose water droplet EGCG emulsion effectively reduced the occurrence of such instability. In alkaline environment (pH = 10), no significant decrease of EGCG was observed in both groups. However, in stronger alkaline environment (pH = 12), the content of EGCG in tea infusion was significantly decreased, while the cellulose water droplet EGCG emulsion still had a small decrease of EGCG. Therefore, it can be determined that the cellulose water droplet EGCG emulsion increased the stability of EGCG in tea under different pH conditions, which is of great significance in overcoming the effects of temperature or pH during the production or storage of products containing EGCG.

[0087] The above is the preferred embodiment of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made, which should also be considered within the scope of protection of the present application.

Claims

1. Use of hydrophobic and hydrophilic algal cellulose in increasing the stability of epigallocatechin gallate, characterized in that, The water-oil dual parent seaweed cellulose is obtained by modifying seaweed extract with wheat germ oil for completing lipophilic modification; The preparation method of the water-oil dual parent seaweed cellulose comprises the following steps: (1) washing and drying seaweed, then mixing and beating the seaweed with water to obtain seaweed gel dispersion; (2) sequentially subjecting the seaweed gel dispersion to stirring treatment and membrane evaporation treatment, and then removing the membrane to obtain seaweed primary extract; (3) treating the seaweed primary extract with wheat germ oil for completing lipophilic modification in a double-cone rotary reactor for 24 hours at a treatment temperature of 40-50 DEG C, and then removing the oil after completion to obtain the water-oil dual parent seaweed cellulose; The temperature of the stirring treatment is 4-8 DEG C, the temperature of the membrane evaporation treatment is 75-85 DEG C, and the seaweed is red seaweed; The mass-to-volume ratio between the seaweed and water is 1:(20-40).

2. A method of preparing a cellulose water microdroplet EGCG emulsion, characterized by, The method comprises the following steps: adding tea extract and water-oil dual parent seaweed cellulose into water to perform high-shear homogenization, and fully mixing the two to obtain a primary emulsion; then adding wheat germ oil into the primary emulsion to continue homogenization, and fully mixing the components to obtain the emulsion; The water-oil dual parent seaweed cellulose is obtained by modifying seaweed extract with wheat germ oil for completing lipophilic modification; The mass-to-volume ratio between the tea extract and water is (0.03-0.05):(4-6); The volume ratio between the water-oil dual parent seaweed cellulose and water is 1:(4-6); The volume ratio between the primary emulsion and plant oil is 1:(3-5); The rotation speed of the homogenizer in the homogenization is 4000 r / min or above; The preparation method of the tea extract comprises the following steps: (1) first soaking of tea leaves: placing tea leaves into a mixed solution of glucose and fructose, first treating the tea leaves under a negative pressure of 0.08-0.1 MPa for 20-30 min, then performing first soaking under normal temperature and pressure, and then removing the filtrate by solid-liquid separation to obtain tea leaves after first soaking; (2) second soaking of tea leaves: placing the tea leaves after first soaking into water to perform second soaking, so that effective components in the tea leaves are fully dissolved in the water, and then removing the tea leaves by solid-liquid separation to obtain tea soaking liquid rich in EGCG; (3) concentrating and crystallizing the tea soaking liquid: using a rotary evaporator to concentrate and crystallize the tea soaking liquid, wherein the reaction conditions are as follows: vacuum negative pressure 0.08-0.09 MPa, water bath temperature 60 DEG C, and adjusting the rotation speed according to the liquid boiling state, with the highest rotation speed being 12, to finally obtain tea extract rich in EGCG; The preparation method of the water-oil dual parent seaweed cellulose comprises the following steps: (1) washing and drying seaweed, then mixing and beating the seaweed with water to obtain seaweed gel dispersion; (2) sequentially subjecting the seaweed gel dispersion to stirring treatment and membrane evaporation treatment, and then removing the membrane to obtain seaweed primary extract; (3) treating the seaweed primary extract with wheat germ oil for completing lipophilic modification in a double-cone rotary reactor for 24 hours at a treatment temperature of 40-50 DEG C, and then removing the oil after completion to obtain the water-oil dual parent seaweed cellulose; The seaweed is red seaweed; The temperature of the stirring treatment is 4-8 DEG C, and the temperature of the membrane evaporation treatment is 75-85 DEG C.

3. The preparation method of claim 2, wherein In the first steeping of tea leaves, the mixture of glucose and fructose includes 20-30% of glucose, 5-10% of fructose and the rest of water; the mass and volume ratio between tea leaves and the mixture of glucose and fructose is (0.5-1.5):(0.5-1.5); the steeping time is 20-30h.

4. The preparation method of claim 2, wherein, In the second steeping of tea leaves, the mass and volume ratio between tea leaves and water is (0.5-1.5):(5-15); the steeping temperature is 70-90℃; the steeping time is 3-5h.

5. A cellulose water microdroplet EGCG emulsion characterized in that, The tea is prepared by the preparation method of any one of claims 2-4.

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