EGCG-loaded β-lactoglobulin gel, its preparation method and application

Abstract

This invention discloses a method for preparing EGCG-loaded β-lactoglobulin self-assembled gels, belonging to the field of biomaterials technology. The invention prepares a β-lactoglobulin self-assembled solution through gradient heating and obtains a highly EGCG-loaded fibrous β-lactoglobulin self-assembled gel via dual-cation-driven combined electrostatic adsorption. The fibrous β-lactoglobulin self-assembled gel prepared by this invention lowers the critical gel concentration of conventionally prepared protein gels; improves gel strength and water-holding capacity; and simultaneously increases the encapsulation rate and loading of EGCG while reducing the release rate, providing a new approach for the encapsulation and sustained-release pathway of bioactive substances.

Description

Technical Field

[0001] This invention belongs to the field of biomaterials technology, specifically relating to EGCG-loaded β-lactoglobulin gels, their preparation methods, and applications. Background Technology

[0002] Protein-formed gels have long been a research hotspot in food colloids due to their excellent biocompatibility, biodegradability, and non-toxicity, leading to their widespread application in food, biomedicine, and chemistry. β-lactoglobulin is a major component of whey protein, accounting for approximately 50% of whey protein and about 12% of the total protein content in milk, with an average concentration of 2-3 g / L. β-lactoglobulin possesses excellent functional properties, such as antioxidant activity, enzymatic hydrolysis properties, gelling properties, emulsifying properties, foaming properties, and water-holding capacity. The preparation of gel carriers utilizing the gelling properties of β-lactoglobulin has also attracted increasing attention. However, traditional protein gel preparation methods require high critical gel concentrations, the gels are susceptible to stress breakage, and the sustained-release performance is weak, affecting the integrity of the gel network and hindering its application as a carrier.

[0003] Epigallocatechin gallate (EGCG) is a major component of tea polyphenols in tea, possessing excellent antioxidant and anti-tumor effects, and is therefore frequently used in cosmetics, pharmaceuticals, and food. However, EGCG exhibits poor stability due to its susceptibility to factors such as pH and temperature. Furthermore, its strong hydrophilicity results in low bioavailability. Therefore, selecting a suitable carrier to encapsulate EGCG can improve its stability and broaden its application range.

[0004] Therefore, it is necessary to develop a solution to improve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide EGCG-loaded β-lactoglobulin gel, its preparation method, and its application, so as to improve the problems of high critical gel concentration, easy gel breakage under stress, and weak sustained-release performance in the preparation of traditional protein gels, while improving the delivery and sustained-release performance of EGCG, and providing a new idea for the encapsulation and sustained-release pathway of bioactive substances.

[0006] On one hand, the present invention provides a method for preparing a β-lactoglobulin gel with high EGCG loading, comprising the following steps:

[0007] β-lactoglobulin powder was dissolved in ultrapure water to obtain solution one;

[0008] Adjust the pH of solution one to 2.0, centrifuge and collect the supernatant, then dilute the mass concentration of β-lactoglobulin to 6-7% to obtain solution two;

[0009] The solution was subjected to gradient water bath heating, and immediately ice bath after heating was completed to obtain a fibrous β-lactoglobulin autoassembly solution.

[0010] After adjusting the pH of the autologous solution to 7.5, it was mixed with EGCG to obtain mixed solution one;

[0011] The mixed solution was used to obtain a fibrous β-lactoglobulin self-assembly gel precursor via dual cation drive;

[0012] The fibrous β-lactoglobulin self-assembly gel was prepared by electrostatic adsorption of the fibrous β-lactoglobulin self-assembly gel precursor.

[0013] Optionally, the β-lactoglobulin has a purity of 95%.

[0014] Optionally, in the step of gradient water bath heating of the second solution, the gradient of the gradient water bath heating is 70℃-90℃.

[0015] Optionally, in the step of adjusting the pH of the autosome solution to 7.5 and mixing it evenly with EGCG, a first mixed solution is obtained, wherein the mass ratio of EGCG to β-lactoglobulin in the first mixed solution is 1:300.

[0016] Optionally, in the step of obtaining the fibrous β-lactoglobulin self-assembly gel precursor by passing the mixed solution through a dual-cation drive, the dual-cation drive cations include calcium ions and manganese ions.

[0017] Optionally, the total cation strength driven by the dual cations is 100 mmol / L.

[0018] Optionally, in the step of preparing the fibrous β-lactoglobulin self-assembly gel by electrostatic adsorption of the fibrous β-lactoglobulin self-assembly gel precursor, the electrostatic adsorption solution used in the electrostatic adsorption is a chitosan solution.

[0019] Optionally, the electrostatic adsorption includes the following steps:

[0020] The fibrous β-lactoglobulin self-assembled gel precursor was uniformly divided into cubes of the same volume.

[0021] The cube was placed in a chitosan solution and adsorbed for 40 minutes to obtain a fibrous β-lactoglobulin self-assembly gel.

[0022] On the other hand, the present invention provides a β-lactoglobulin gel with a high EGCG loading.

[0023] Optionally, the β-lactoglobulin gel with high EGCG loading prepared by the present invention can be used in the food and pharmaceutical fields.

[0024] The beneficial effects of this invention include:

[0025] (1) The preparation method provided by the present invention prepares β-lactoglobulin self-organizing gel by utilizing the highly ordered spontaneous organization of reversible or irreversible aggregation driven by chemical reaction or non-covalent interaction. It has the advantages of being simple and easy to implement, low cost, safe and non-toxic, and having good reproducibility.

[0026] (2) The preparation method provided by the present invention can better control the shape, structure and texture of the gel through dual cation drive, and endow the gel carrier with excellent biocompatibility and biodegradability.

[0027] (3) The β-lactoglobulin self-assembly precursor obtained by the preparation method of the present invention has high surface hydrophobicity and stable and ordered aggregate structure, which is conducive to the formation of β-lactoglobulin self-assembly gel, improves gel strength, and improves the problem of easy breakage under stress.

[0028] (4) The β-lactoglobulin self-assembled gel prepared by the method of the present invention has strong water-holding capacity and high mechanical strength, thus possessing the advantage of strong sustained-release performance.

[0029] (5) The β-lactoglobulin self-assembled gel prepared by the method of the present invention, compared with the gel prepared by the traditional method, can improve the embedding rate and loading capacity of EGCG, while also improving the stability and bioavailability of EGCG in the gel. Attached Figure Description

[0030] Figure 1 These are typical macroscopic visual images of the β-lactoglobulin gels prepared in Example 1 and Comparative Examples 1-3;

[0031] Figure 2 This is a transmission electron microscope image of the natural β-lactoglobulin used in Example 1;

[0032] Figure 3 This is a transmission electron microscope image of the fibrous β-lactoglobulin self-assembly prepared in Example 1;

[0033] Figure 4 This is a scanning electron microscope image of the fibrous β-lactoglobulin self-assembled gel prepared in Example 1;

[0034] Figure 5 This is a temperature scan of the 6% (w / w) fibrous β-lactoglobulin self-assembly gel driven by the dual cations CaCl2 and MnCl2 prepared in Example 1.

[0035] Figure 6 This is a temperature scan of a conventional heat-induced β-lactoglobulin gel with a mass concentration of 10% prepared in Comparative Example 1.

[0036] Figure 7 This is a temperature scan of the fibrous β-lactoglobulin self-assembled gel prepared from a 6% (w / w) CaCl2 single-cation-driven β-lactoglobulin solution prepared in Comparative Example 2.

[0037] Figure 8 This is a temperature scan of the fibrous β-lactoglobulin self-assembled gel prepared from a 6% (w / w) β-lactoglobulin solution driven by a single MnCl2 cation, as shown in Comparative Example 3. Detailed Implementation

[0038] The present invention will be further described in conjunction with the accompanying drawings and the following embodiments.

[0039] This invention provides a method for preparing EGCG-loaded β-lactoglobulin self-assembled gel, comprising the following steps:

[0040] S1. Dissolve β-lactoglobulin powder in ultrapure water to obtain solution one;

[0041] S2. Adjust the pH of the first solution, centrifuge and collect the supernatant, correct the pH of the supernatant, and dilute the mass concentration of β-lactoglobulin to 6-7% to obtain the second solution.

[0042] S3. The solution 2 is heated in a gradient water bath, and then immediately placed in an ice bath after heating to obtain a fibrous β-lactoglobulin self-assembly precursor solution.

[0043] S4. Adjust the pH of the self-assembled precursor solution to 7.5 and mix it with EGCG to obtain mixed solution one;

[0044] S5. The mixed solution was subjected to dual cation-driven processing to obtain a fibrous β-lactoglobulin self-assembly gel precursor.

[0045] S6. The fibrous β-lactoglobulin self-assembly gel is prepared by electrostatic adsorption of the fibrous β-lactoglobulin self-assembly gel precursor.

[0046] In some embodiments, the β-lactoglobulin described in step S1 has a purity of 95%.

[0047] Specifically, the water in step S1 includes pure water and ultrapure water.

[0048] In some embodiments, the acidity regulator used to adjust and correct the pH of the β-lactoglobulin solution in step S2 is citric acid with a mass concentration of 10%.

[0049] In some embodiments, the gradient of the gradient water bath heating in step S3 is 70°C-90°C.

[0050] In some embodiments, the mass ratio of EGCG to β-lactoglobulin in step S4 is 1:300.

[0051] In some embodiments, the cations driven by the dual cations in step S5 include calcium ions and manganese ions.

[0052] In some embodiments, the total cation strength driven by the dual cations in step S5 is 100 mmol / L.

[0053] In some embodiments, the electrostatic adsorption solution used in step S5 is a chitosan solution.

[0054] Specifically, the concentration of the chitosan solution is 10 mg / mL.

[0055] Specifically, the chitosan solution has a degree of deacetylation ≥95% and a viscosity of 100-200 mPa·s.

[0056] Optionally, the electrostatic adsorption in step S5 includes the following steps:

[0057] The fibrous β-lactoglobulin self-assembled gel precursor was uniformly divided into cubes of the same volume.

[0058] The cube was placed in a chitosan solution and adsorbed for 40 minutes to obtain a fibrous β-lactoglobulin self-assembly gel.

[0059] On the other hand, the present invention provides a β-lactoglobulin self-assembly gel loaded with EGCG.

[0060] Optionally, the β-lactoglobulin gel with high EGCG loading prepared by the present invention can be used in the food and pharmaceutical fields.

[0061] Example 1

[0062] Example 1 of this invention provides a method for preparing EGCG-loaded β-lactoglobulin self-assembly gels via dual-cation drive, comprising the following steps:

[0063] S1. Dissolve β-lactoglobulin powder in ultrapure water to obtain a β-lactoglobulin solution with a mass concentration of 6%, i.e., solution one;

[0064] S2. Add 10% citric acid to solution one to adjust the pH to 2.0;

[0065] Centrifuge at 4000×g and 4℃ for 20 min, collect the supernatant, and determine the protein content of the supernatant.

[0066] The concentration of β-lactoglobulin in the supernatant was diluted to 6%, and citric acid was added to adjust the pH to 2.0 to obtain solution two;

[0067] S3. Induce solution 2 under a continuous temperature gradient, i.e., heat in a 70-80℃ water bath for 1 hour, in a 85℃ water bath for 2 hours, and in a 90℃ water bath for 7 hours. After heating, immediately place it in an ice bath to cool and obtain a fibrous β-lactoglobulin self-assembly precursor solution.

[0068] S4. Add NaOH to the protein autogenous precursor solution obtained in step S3 to adjust the pH to 7.5; add EGCG and mix. The mass ratio of EGCG to β-lactoglobulin is 1:300. Mix evenly to obtain mixed solution one.

[0069] S5. Add a mixed solution of CaCl2 and MnCl2 cations to mixed solution one for cation-driven reaction. The total ionic strength of the mixed solution is 100 mmol / L, to obtain mixed solution two.

[0070] After the driving process is completed, seal the mixed solution and heat it in an 80°C water bath for 30 minutes. After heating, immediately cool it in an ice-water bath.

[0071] After cooling, a fibrous β-lactoglobulin self-assembly gel precursor is obtained;

[0072] S6. The fibrous β-lactoglobulin self-assembled gel precursor obtained in step S5 is evenly divided into cubes of the same volume, each measuring 2cm × 2cm × 2cm.

[0073] The obtained cubes of the same volume were placed in a chitosan solution dissolved in 2% acetic acid at a concentration of 10 mg / mL (the pH of the chitosan solution was adjusted to 6.0) and subjected to electrostatic adsorption for 40 min.

[0074] After electrostatic adsorption, a fibrous β-lactoglobulin self-assembly gel loaded with 6% EGCG was obtained.

[0075] Comparative Example 1

[0076] Comparative Example 1 of this invention provides a method for preparing a conventional β-lactoglobulin heat-induced gel loaded with 10% EGCG, comprising the following steps:

[0077] D1. Dissolve β-lactoglobulin powder in ultrapure water to prepare a 10% (w / w) β-lactoglobulin solution:

[0078] D2. Add EGCG solution to the β-lactoglobulin solution while stirring dropwise to make the mass ratio of EGCG to β-lactoglobulin in the mixed solution 1:300, thus obtaining EGCG-loaded mixed solution one;

[0079] D3. Heat the above mixed solution in an 80°C water bath for 30 minutes, and then cool it in an ice bath to obtain a conventional β-lactoglobulin thermo-induced gel loaded with EGCG at a mass concentration of 6%.

[0080] Comparative Example 2

[0081] Comparative Example 2 of the present invention provides a method for preparing a self-organized gel of EGCG-loaded fibrous β-lactoglobulin driven by a single CaCl2 cation. The difference from Example 1 is that in step S5, only the CaCl2 solution is used for cation driving, while other conditions and steps remain the same.

[0082] Comparative Example 3

[0083] Comparative Example 2 of the present invention provides a method for preparing EGCG-loaded fibrous β-lactoglobulin self-organizing gel driven by a single MnCl2 cation. The difference from Example 1 is that in step S5, only MnCl2 solution is used for cation driving, while other conditions and steps remain the same.

[0084] Macroscopic and microscopic morphological characterization

[0085] Macroscopic visual image Figure 1 As shown, from left to right:

[0086] The fibrous β-lactoglobulin self-assembly gel with a mass concentration of 6% driven by CaCl2 and MnCl2 dual cations was prepared in Example 1;

[0087] The conventional heat-induced β-lactoglobulin gel with a mass concentration of 10% prepared in Comparative Example 1;

[0088] The fibrous β-lactoglobulin self-assembly gel with a mass concentration of 6% driven by CaCl2 single cation was prepared in Comparative Example 2.

[0089] The fibrous β-lactoglobulin self-assembly gel with a mass concentration of 6% driven by MnCl2 single cation was prepared in Comparative Example 3.

[0090] The microstructure of natural β-lactoglobulin and the β-lactoglobulin self-assembly loaded with EGCG at a mass concentration of 6% prepared in Example 1 were characterized by transmission electron microscopy.

[0091] Microscopic morphological characterization of natural β-lactoglobulin includes the following steps:

[0092] A dispersion of natural β-lactoglobulin with a mass concentration of 0.1% (w / v) was prepared.

[0093] The dispersion was dropped onto a 300-mesh copper grid coated with a carbon film and dried for 15 minutes.

[0094] After drying, stain with phosphotungstic acid for 5 minutes, and after drying for 15 minutes, observe the microstructure of natural β-lactoglobulin under a transmission electron microscope.

[0095] The microscopic morphology characterization of the β-lactoglobulin self-assemblies prepared in Example 1 includes the following steps:

[0096] The concentration of the fibrous β-lactoglobulin self-assembled solution was diluted to 0.1% (w / v) to obtain a dispersion;

[0097] The dispersion was dropped onto a 300-mesh copper grid coated with a carbon film and dried for 15 minutes.

[0098] After drying, the fibrous β-lactoglobulin self-assemblies were stained with phosphotungstic acid for 5 minutes. After staining, they were dried for 15 minutes and then observed under a transmission electron microscope to observe the microstructure of the fibrous β-lactoglobulin self-assemblies.

[0099] Transmission electron microscopy image of natural β-lactoglobulin as shown below Figure 2 As shown;

[0100] The results of transmission electron microscopy observation of the fibrous β-lactoglobulin self-assemblies prepared in Example 1 are as follows: Figure 3 As shown;

[0101] Meanwhile, the fibrous β-lactoglobulin self-assembled gel prepared in Example 1 was characterized by scanning electron microscopy, including the following steps:

[0102] The fibrous β-lactoglobulin self-assembled gel prepared in Example 1 was freeze-dried for 48 hours.

[0103] After slicing the material into thin slices with a blade, fix the cross-section onto a metal frame and spray gold onto it.

[0104] The voltage was set to 20kV to observe the microstructure of the gel surface.

[0105] The scanning electron microscopy observation results of the fibrous β-lactoglobulin self-assembled gel prepared in Example 1 are as follows: Figure 4 As shown;

[0106] See Figure 2 , Figure 3 and Figure 4 The fibrous β-lactoglobulin self-assembly prepared in Example 1 formed a protein fiber structure with a length of micrometers. This fiber structure, which has high hydrophobicity, high β-folding ability and strong positive charge, is conducive to the construction of the gel system. The fibrous β-lactoglobulin self-assembled gel prepared in Example 1 has a dense cross-linked three-dimensional porous gel network structure. This dense and ordered gel network structure is conducive to the interaction between water molecules and hydrophilic groups, so that water molecules can be stably retained in the gel network structure.

[0107] Rheological property testing

[0108] The rheological properties of the self-assembled gel prepared in Example 1 and the gels prepared in Comparative Examples 1, 2, and 3 were tested, including the following steps:

[0109] The rheological properties of the samples were determined using an MCR 302 rheometer, with the temperature of the plate system controlled by a Peltier system.

[0110] Seal the edges of the gel with silicone oil before testing to prevent moisture evaporation;

[0111] The fully driven mixed solutions obtained in step S5 of Example 1 and Comparative Examples 1, 2 and 3 were subjected to temperature scanning experiments on a rheometer plate.

[0112] Experimental parameters: heating from 25℃ to 80℃ at a rate of 5℃ / min, and holding at 80℃ for 30min.

[0113] Cool the temperature to 25°C, keeping the cooling rate consistent with the heating rate, and maintain the temperature at 25°C for 10 minutes.

[0114] The oscillation parameter is constant at 1%, and the frequency is constant at 1Hz;

[0115] Take a modulus point every half minute;

[0116] The temperature scanning results of the fibrous β-lactoglobulin self-assembly gel prepared in Example 1, driven by two cations, are as follows: Figure 5 As shown;

[0117] Temperature scanning experiments were conducted on mixed solution one in Comparative Example 1 and mixed solution two in Comparative Examples 2 and 3 according to the above parameter settings.

[0118] The conventional heat-induced β-lactoglobulin gel prepared in Comparative Example 1, such as Figure 6 As shown;

[0119] The fibrous β-lactoglobulin self-assembly gel prepared in Comparative Example 2, driven by a single CaCl2 cation, is as follows: Figure 7 As shown;

[0120] The fibrous β-lactoglobulin self-assembly gel prepared in Comparative Example 3, driven by a single MnCl2 cation, is as follows: Figure 8 As shown;

[0121] See Figure 5 , Figure 6 , Figure 7 , Figure 8 It can be observed that the fibrous β-lactoglobulin self-assembled gel prepared in Example 1 has good elastic properties, and also shortens the gelation time and reduces the critical gel concentration; compared with Comparative Examples 1-3, it can better load EGCG and obtain better delivery and sustained release performance.

[0122] Performance testing

[0123] The mechanical strength, water holding capacity, EGCG loading and release of the β-lactoglobulin self-assembled gel prepared in Example 1 and the gels prepared in Comparative Examples 1, 2 and 3 were tested.

[0124] (1) The gel strength test includes the following steps:

[0125] The gel strength of the samples was determined using a TA-XT Plus texture analyzer; a P / 0.5 cylindrical probe with a trigger force of 5g was used.

[0126] The gel sample was compressed at a compression rate of 10 mm / min.

[0127] The measured gel strengths are shown in Table 1.

[0128] (2) The water-holding capacity test includes the following steps:

[0129] Weigh the empty centrifuge tube and record the mass as W0.

[0130] A certain amount of the β-lactoglobulin self-assembled gel prepared in Example 1 was placed in a centrifuge tube; the weight was measured and recorded as W1.

[0131] Centrifuge at 4000×g for 20 min, and use filter paper to remove excess water; weigh the mass after removing water and record it as W2.

[0132] The formula for calculating water-holding capacity is: Water-holding capacity = (W2-W0) / (W1-W0)×100%, which is defined as the mass percentage of the gel before and after centrifugation;

[0133] The water-holding capacity of the gel was measured and the results are shown in Table 1.

[0134] (3) Establishment of the EGCG standard curve

[0135] Weigh 1 mg of EGCG standard using a 1 / 10,000 electronic balance, dissolve it in distilled water to prepare a 1 mg / mL EGCG standard stock solution, and then dilute the concentration with distilled water to 1 μg / mL, 5 μg / mL, 10 μg / mL, 15 μg / mL and 20 μg / mL to obtain EGCG standard solutions of different concentrations.

[0136] The absorbance of EGCG standard solutions of different concentrations at 272 nm was measured using a UV spectrophotometer. A standard curve was plotted with EGCG solution concentration (c) as the abscissa and absorbance (A) as the ordinate. The content of EGCG was calculated based on the standard curve.

[0137] The final standard curve for EGCG is A = 320.224c + 0.03698.

[0138] (4) Testing of EGCG encapsulation efficiency and drug loading includes the following steps:

[0139] Dissolve an appropriate amount of fibrous β-lactoglobulin self-assembled gel in distilled water;

[0140] Centrifuge at 4500×g for 15 min at room temperature, dilute the supernatant with distilled water, and measure the absorbance of the supernatant at 272 nm; substitute the measured absorbance into the above standard curve to calculate the free EGCG content; the total amount of EGCG is the amount added encapsulated in the gel.

[0141] The encapsulation rate is calculated as follows: Encapsulation rate (%) = (Total EGCG) / (Free EGCG content) × 100%, which is defined as the percentage of total EGCG to free EGCG content.

[0142] The formula for calculating drug loading is: Drug loading (μg / mg) = (Total EGCG - Free EGCG content) / Gel protein content, which is defined as the ratio of the difference between the total EGCG and the free EGCG content to the protein content in the gel.

[0143] The encapsulation efficiency and drug loading of the gels in Example 1 and Comparative Examples 1-3 were tested respectively, and the results are shown in Table 1.

[0144] (5) In vitro digestion testing, including the following steps:

[0145] Place 50 mL of simulated gastric fluid containing pepsin in an Erlenmeyer flask and incubate in a constant temperature water bath at 37°C for 5 min.

[0146] After the water bath is complete, add the EGCG-loaded fibrous β-lactoglobulin self-assembled gel and quickly vortex for 30 seconds to mix.

[0147] After mixing, place in a 37℃ magnetically stirred water bath for digestion for 3 hours;

[0148] After digestion, the sample was centrifuged at 4500×g for 15 min at room temperature. The absorbance of the supernatant was measured at 272 nm. After the measurement, the EGCG release was calculated by substituting the measured absorbance value into the standard curve.

[0149] The formula for calculating the release rate is: Release rate (%) = EGCG 释放量 / EGCG 总量 ×100%, defined as the percentage of EGCG released relative to the total amount of EGCG;

[0150] The EGCG release amount of chitosan prepared in Example 1 and Comparative Examples 1-3 before and after chitosan adsorption was detected, and the EGCG release rate is shown in Table 1.

[0151] The EGCG release rates of each gel are shown in Table 1:

[0152] Table 1 Performance Test Results

[0153]

[0154] See Table 1, which uses letter notation to show the significant differences among groups in terms of hardness, water holding capacity, and burial rate;

[0155] The gel hardness in Example 1 is significantly higher than that in Comparative Example 1, meaning that the self-assembled gel provided by the present invention has higher gel mechanical strength compared with traditional thermally conductive gels; compared with Comparative Examples 2-3, it is confirmed that dual-cation driving can make the gel harder.

[0156] Similarly, it can be seen that the dual-cation-driven self-assembly gel provided by the present invention has better performance in all aspects; it proves that the self-assembly gel method and dual-cation-driven method provided by the present invention greatly improve the mechanical strength, water holding capacity and gel delivery sustained-release performance of the gel, which is significant for the controlled release of bioactive substances in the carrier and has broad application prospects in the fields of functional nutritional foods and special medical foods.

[0157] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for preparing a self-assembled gel of β-lactoglobulin loaded with EGCG, characterized in that, Includes the following steps: After adjusting the pH of the β-lactoglobulin solution to 2.0, a gradient water bath heating process was performed, followed by an ice bath to obtain the autosome solution; wherein the mass concentration of β-lactoglobulin in the β-lactoglobulin solution was 6-7%; After adjusting the pH of the autologous solution to 7.5, it was mixed with EGCG to obtain a mixed solution; The preparation of a self-assembly gel precursor via dual-cation driving includes: adding a dual-cation mixed solution to a mixed solution for reaction; sealing the solution after the reaction is complete; heating in a water bath at 80 °C for 30 min; and immediately cooling in an ice-water bath after heating to obtain the self-assembly gel precursor; wherein the dual-cation mixed solution is a mixture of calcium chloride and manganese chloride. β-lactoglobulin self-assembly gel was prepared by electrostatic adsorption of the self-assembly gel precursor, wherein the electrostatic adsorption solution used in the electrostatic adsorption was a chitosan solution.

2. The method according to claim 1, characterized in that, Citric acid is used as the acidity regulator to adjust the pH of β-lactoglobulin solution.

3. The method according to claim 1, characterized in that, After adjusting the pH of the autosome solution to 7.5 and mixing it with EGCG, the mass ratio of EGCG to β-lactoglobulin was 1:

300.

4. The method according to claim 1, characterized in that, The total cation strength driven by the dual cations is 100 mmol / L.

5. The method according to claim 1, characterized in that, The electrostatic adsorption includes the following steps: The self-assembly gel precursor is uniformly divided into cubes of equal volume; The cube was placed in a chitosan solution and adsorbed for 40 min to obtain a fibrous β-lactoglobulin self-assembly gel.

6. A β-lactoglobulin self-assembly gel loaded with EGCG prepared by the preparation method according to any one of claims 1-5.

7. The application of the EGCG-loaded β-lactoglobulin self-assembly gel as described in claim 6 in the preparation of functional nutritional foods and special medical foods.

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