Composite coacervates based on whey protein isolate and theabrownin, and methods of making and using the same

Abstract

The application belongs to the embedding and slow-release technical field of protein, and particularly relates to a composite coacervate based on whey protein isolate and theabrownine as well as a preparation method and application thereof. The theabrownine and the whey protein isolate are respectively dissolved in an aqueous solution, and the whey protein isolate-theabrownine composite coacervate is prepared by controlling the ratio of the whey protein isolate aqueous solution and the theabrownine aqueous solution, the pH value of the system and the ionic strength. Compared with the prior art, the application takes electrostatic interaction as a driving force, realizes the preparation of the whey protein isolate-theabrownine composite coacervate by controlling process parameters and adjusting the intramolecular and intermolecular electrostatic interaction, and provides important technical support for preparing novel food ingredients with various structures and rich functions.

Description

Technical Field

[0001] This invention belongs to the field of protein encapsulation and sustained release technology, and in particular relates to a composite coagulant based on whey protein isolate and theabrownin, its preparation method and application. Background Technology

[0002] Theabrownins (TB), derived from dark tea, are a type of tea pigment formed by the oxidation of polyphenols. They were first discovered in the 1960s. TB is a natural polymer with a large and heterogeneous molecular weight and complex composition. It has good water solubility and its solid powder is dark brown. Unlike thearubigins and theaflavins, TB accounts for a high proportion of the total content in dark tea, reaching about 12%. It can be said that the unique properties of dark tea, distinguishing it from other teas, are largely due to TB. Therefore, the TB content can be used as an important indicator to evaluate the quality of dark tea. With the gradual optimization of TB extraction technology, the purity and yield of extracted TB have gradually increased. Consequently, research on the biological functions of TB has become increasingly extensive. TB possesses powerful biological functions, showing significant effects in lowering lipids, anti-oxidation, anti-inflammation, anti-cancer, regulating intestinal flora, and treating osteoporosis. Whey protein is a general term for a class of soluble milk proteins that provide all the essential amino acids required by the human body. It is a highly bioavailable protein, easily absorbed by the body, and rich in various bioactive substances. Whey protein (WP) accounts for approximately 18-20% of the total milk protein. It can be obtained as a byproduct (whey) of casein precipitation or extracted directly from milk using modern food production techniques. Whey protein is a potentially rich natural source of bioactive compounds with powerful health benefits. Whey protein isolate (WPI) is a further purified product of whey protein; only whey isolates with at least 90% protein purity can be classified as WPI.

[0003] Co-aggregation typically occurs when oppositely charged biopolymers in an aqueous medium establish electrostatic interactions and achieve electrostatic equilibrium within the aggregated phase. The two most typical examples are proteins and polysaccharides. At suitable pH values, proteins and polysaccharides dissolved in water associate to form phase separation, resulting in two phases: a polymer-poor phase and a polymer-rich phase. Co-aggregation has applications in various scenarios, such as encapsulating small-molecule active substances, resolving precipitation in beverages, stabilizing emulsions, producing composite hydrogels, and preparing edible films. Liu Wanlong's research found that using co-aggregation to prepare microcapsules encapsulating plant aromatic essential oils better preserves aroma and stabilizes active components. Besides essential oils, other fat-soluble components can also be prepared into microcapsules using co-aggregation. Co-aggregation between proteins, also known as heteroprotein co-aggregation, can be used to separate and purify selected proteins. Pathak et al. adjusted the pH of a mixed protein solution (BSA / β-LG / gelatin B) to 5.0 to separate individual proteins from solutions with similar isoelectric points and zeta potentials. Selective aggregation and phase separation occurred in the BSA / gelatin B aggregate, and β-LG was collected from the supernatant. Ethanol was then added to the BSA / gelatin B aggregate to precipitate gelatin B, while BSA remained in the supernatant. Bourbon et al. found that lactoferrin and glycomacropeptides could be gelled into nano-hydrogels through electrostatic interactions and thermal treatment. Oliveira et al. discovered that soy protein isolate (SPI)-based films reinforced with carboxymethyl cellulose (CMC) exhibited good mechanical and barrier properties. The protein-polysaccharide composite aggregation significantly affects the film properties, indicating that composite aggregation offers various possibilities for fabricating films and edible coatings.

[0004] Patent CN116391854A discloses a sodium-loaded composite coagulant, its preparation method, and its application. The preparation method includes the following steps: S1, dissolving whey protein isolate to obtain a whey protein isolate stock solution; S2, dissolving polysaccharide to obtain a polysaccharide stock solution; S3, mixing the whey protein isolate stock solution obtained in step S1 and the polysaccharide stock solution obtained in step S2 to obtain a whey protein isolate-polysaccharide mixed solution; S4, adding sodium chloride to the whey protein isolate-polysaccharide mixed solution obtained in step S3 to obtain a sodium-loaded composite coagulant.

[0005] Patent CN110623250A discloses a method for preparing a cellulose nanocrystal-whey protein isolate composite thermogel. The steps are as follows: 1) Preparing a cellulose nanocrystal-whey protein isolate mixed solution: cellulose nanocrystals, whey protein isolate, and deionized water are mixed evenly in a certain proportion. The pH value of the mixture is adjusted to 5-9. After thorough stirring, the mixture is allowed to stand at 4°C for 10-12 hours to allow complete protein hydration, resulting in a cellulose nanocrystal-whey protein isolate mixed solution; 2) Preparing the cellulose nanocrystal-whey protein isolate composite thermogel. This preparation method can improve the water retention, strength, and elasticity of the whey protein isolate composite thermogel.

[0006] In conclusion, composite cohesion has great potential for materials in developing innovative foods with unique functional properties.

[0007] However, there are no reports in the existing technology on how to prepare whey protein isolate and theabrownin complex aggregates. Summary of the Invention

[0008] Given the lack of existing methods for preparing whey protein isolate and theabrownin complex coagulates, this invention provides a complex coagulate based on whey protein isolate and theabrownin, its preparation method, and its application.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a complex aggregate based on whey protein isolate and theabrownin, comprising the following steps:

[0011] S1. Dissolve whey protein isolate to obtain whey protein isolate aqueous solution, and dissolve theabrownin to obtain theabrownin aqueous solution;

[0012] S2. Mix the whey protein isolate aqueous solution and the theabrownin aqueous solution obtained in step S1 to obtain a whey protein isolate-theabrownin mixed solution;

[0013] S3. Add hydrochloric acid to the whey protein isolate-theabrownin mixed solution obtained in step S2 to obtain a complex aggregate based on whey protein isolate and theabrownin.

[0014] In one embodiment of the present invention, in step S1, the concentration of the whey protein isolate aqueous solution is 1 to 10 mg / mL; preferably, the concentration of the whey protein isolate aqueous solution is 1 mg / mL, 3 mg / mL, 5 mg / mL, 8 mg / mL, or 10 mg / mL; and further, the concentration of the whey protein isolate aqueous solution is 10 mg / mL.

[0015] In one embodiment of the present invention, in step S1, the concentration of the theabrownin aqueous solution is 1 to 10 mg / mL; preferably, the concentration of the theabrownin aqueous solution is 1 mg / mL, 3 mg / mL, 5 mg / mL, 8 mg / mL, or 10 mg / mL; and further, the concentration of the theabrownin aqueous solution is 10 mg / mL.

[0016] In one embodiment of the present invention, in step S1, the concentrations of the theabrownin aqueous solution and the whey protein isolate aqueous solution are both 10 mg / mL.

[0017] In one embodiment of the present invention, in step S1, the number-average molecular weight of the theabrownin and whey protein isolate is 30,000 to 70,000 Daltons.

[0018] In one embodiment of the present invention, in step S1, whey protein isolate is added to distilled water and stirred to dissolve, thereby obtaining an aqueous solution of whey protein isolate.

[0019] In one embodiment of the present invention, in step S1, theabrownin is added to distilled water and stirred to dissolve, thereby obtaining an aqueous solution of theabrownin.

[0020] In one embodiment of the present invention, in step S2, the volume ratio of the whey protein isolate aqueous solution and the theabrownin aqueous solution is 1:1 to 15:1; preferably, the volume ratio of the whey protein isolate aqueous solution and the theabrownin aqueous solution is 1:1, 3:1, 5:1, 10:1, or 15:1; further, the volume ratio of the whey protein isolate aqueous solution and the theabrownin aqueous solution is 10:1.

[0021] In one embodiment of the present invention, in step S3, after adding hydrochloric acid to the whey protein isolate-theabrownin mixed solution, the pH range is adjusted to 3.2-5.6; preferably, the pH of the whey protein isolate-theabrownin mixed solution is adjusted to 5.6, 5.5, 5.0, 4.5, 4.0, 3.5, 3.2; and further, the pH of the whey protein isolate-theabrownin mixed solution is adjusted to 5.5.

[0022] In step S3, when the pH of the system is adjusted to be greater than 5.6 and less than 7.0, theabrownin and whey protein isolate form a uniformly dispersed system with no intermolecular dispersion, and no complex aggregate is formed at this time;

[0023] In step S3, when the pH of the system is adjusted to be greater than 5.4 and less than 5.6, theabrownins and whey protein isolates begin to aggregate, forming soluble complex coagulants.

[0024] In step S3, when the pH of the system is adjusted to be greater than 4.8 and less than 5.4, theabrownin and whey protein isolate form an insoluble complex aggregate. At this time, the electrostatic repulsion between molecules in the system gradually approaches zero, resulting in a turbid state and precipitation.

[0025] In step S3, when the pH of the system is adjusted to be greater than 3.2 and less than 4.8, theabrownins and whey protein isolate form an insoluble complex aggregate. At this time, the electrostatic repulsion between molecules in the system gradually increases, the precipitate begins to dissociate, and the system still appears turbid.

[0026] In step S3, when the pH of the system is adjusted to be greater than 2.0 and less than 3.2, the whey protein isolate-theabrownin complex aggregate completely dissociates. At this point, the electrostatic repulsion between molecules in the system increases, and the molecules are uniformly dispersed.

[0027] In one embodiment of the present invention, in step S3, sodium chloride is used to adjust the ionic strength of the whey protein isolate-theabrownin mixed solution to 0-200 mM, preferably 0, 25, 50, 100, or 200 mM.

[0028] In one embodiment of the present invention, in step S3, the operating temperature is room temperature.

[0029] In one embodiment of the present invention, in step S3, the shape of the obtained whey protein isolate-theabrownin complex aggregate includes block shape and rod shape.

[0030] In a second aspect, the present invention provides a whey protein isolate-theabrownin complex aggregate obtained by the above preparation method.

[0031] A third aspect of the present invention provides the application of whey protein isolate-theabrownin complex coagulates obtained by the above preparation method, wherein the whey protein isolate-theabrownin complex coagulates are used in the preparation of food.

[0032] In this invention, whey protein isolate-theabrownin complex coagulates can be used to develop low-cost, highly efficient, stable, safe, and environmentally friendly food products. In the future food industry, complex coagulates have application value in various scenarios, such as encapsulating small-molecule active substances, solving precipitation problems in beverages, stabilizing emulsions, producing composite hydrogels, and preparing edible films.

[0033] This invention provides a method for preparing whey protein isolate-theabrownin complex aggregates. Theabrownin and whey protein isolate are dissolved in water, and by controlling the ratio of theabrownin aqueous solution to the whey protein isolate aqueous solution, the pH value of the system, and the ionic strength, the whey protein isolate-theabrownin complex aggregates can form in various states.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] This invention utilizes electrostatic interactions as the driving force, and by controlling process parameters to regulate intramolecular and intermolecular electrostatic interactions, a whey protein isolate-theabrownin complex aggregate was prepared via a composite coagulation method. This invention provides important technical support for the preparation of novel food ingredients with diverse structures and rich functions. Furthermore, this invention has the advantages of simple operation, low cost, scalability, and reproducibility. Attached Figure Description

[0036] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 Example 1 of the present invention: Turbidity results of condensates under different pH conditions;

[0038] Figure 2 Example 2 of the present invention: Turbidity results of condensates under different ionic strength conditions;

[0039] Figure 3 Example 2 of the present invention: Particle size and potential results of aggregates under different ionic strength conditions;

[0040] Figure 4 Example 3 of the present invention: Turbidity results of condensates under different compound volume conditions;

[0041] Figure 5 Example 3 of the present invention: Particle size and potential results of aggregates under different compound volume conditions;

[0042] Figure 6 : Fluorescence spectrum results of Example 4 of the present invention;

[0043] Figure 7 : Scanning electron microscope results of Embodiment 5 of the present invention.

[0044] Figure 8 Scanning electron microscope image of the raw material theabrownin.

[0045] Figure 9 Scanning electron microscope image of raw whey protein isolate. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0047] In the following examples, the whey protein isolate was purchased from Fonterra and had a purity of 92%.

[0048] Example 1:

[0049] A method for preparing whey protein isolate-theabrownin complex aggregates includes the following steps:

[0050] a) Accurately weigh 1.00 g of commercially available whey protein isolate using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the whey protein isolate aqueous solution is 10 mg / mL.

[0051] b) Accurately weigh 1.00 g of commercially available theabrownin using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the theabrownin aqueous solution is 10 mg / mL.

[0052] c) Prepare a whey protein isolate-theabrownin mixed solution by mixing the above 10 mg / mL whey protein isolate aqueous solution and 10 mg / mL theabrownin aqueous solution at a volume ratio of 10:1.

[0053] d) Adjust the pH of the above whey protein isolate-theabrownin mixed solution to the range of 7.0 to 2.0 with hydrochloric acid. Take a sample of the mixed solution and place it in an ELISA plate for every 0.2 decrease in pH, and measure its turbidity at 600 nm.

[0054] The results showed that, under room temperature conditions (25℃), the turbidity values ​​of the above-mentioned whey protein isolate-theabrownin mixed solution at different pH values ​​were as follows: Figure 1 As shown, the whey protein isolate-theabrownin mixed solution underwent different stages at different pH values. From pH 7.0 to 5.6, no complex coagulations formed in the solution; from pH 5.6 to 5.4, the turbidity value suddenly increased significantly, indicating that complex coagulations were forming, but only soluble complex coagulations were formed at this stage; from pH 5.4 to 3.2, the turbidity value of the solution first rose to a plateau and then slowly decreased, indicating the formation of insoluble complex coagulations, with the largest amount of complex coagulations forming at pH 4.8, after which the complex coagulations began to dissociate; from pH 3.2 to 2.0, the turbidity value of the solution continued to decrease, and no complex coagulations were present in the solution at this point.

[0055] Example 2:

[0056] A method for preparing whey protein isolate-theabrownin complex aggregates includes the following steps:

[0057] a) Accurately weigh 1.00 g of commercially available whey protein isolate using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the whey protein isolate aqueous solution is 10 mg / mL.

[0058] b) Accurately weigh 1.00 g of commercially available theabrownin using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the theabrownin aqueous solution is 10 mg / mL.

[0059] c) Prepare a whey protein isolate-theabrownin mixed solution by mixing the above 10 mg / mL whey protein isolate aqueous solution and 10 mg / mL theabrownin aqueous solution at a volume ratio of 10:1.

[0060] d) Adjust the ionic strength of the above whey protein isolate-theabrownin mixed solution to 0, 25, 50, 100, and 200 mM using sodium chloride.

[0061] e) Adjust the pH of the above whey protein isolate-theabrownin mixed solution to the range of 7.0 to 2.0 with hydrochloric acid. Take a sample of the mixed solution and place it in an ELISA plate for every 0.2 decrease in pH, and measure its turbidity at 600 nm.

[0062] f) In the above steps, take a mixed solution every 0.5 or 1 pH value, dilute it 10 times with distilled water of the same pH, and then use a laser diffraction nanoparticle size analyzer to detect its particle size and potential.

[0063] The results showed that, under room temperature conditions (25℃), the turbidity values ​​of the above-mentioned whey protein isolate-theabrownin mixed solution at different pH values ​​were as follows: Figure 2 As shown. The particle size and potential results of the above whey protein isolate-theabrownin mixed solution at different pH values ​​are as follows. Figure 3 As shown. Figure 2 The results indicate that ionic strength affects complex coagulation through electrostatic shielding, specifically by binding with exposed TB / WPI and thus influencing their electrostatic interaction. The effect of ionic strength on complex coagulation is dose-dependent. With increasing ionic strength, the maximum turbidity of the solution decreases and the characteristic pH shifts towards lower pH values, which inhibits the formation of complex coagulates. The results show that ionic strengths greater than 25 mM inhibit the formation of complex coagulates. Figure 3 This indicates that as ionic strength increases, the pH values ​​at which the solution potential reaches zero and where the particle size is largest all shift towards lower pH values. This hinders the formation of complex aggregates and is also related to... Figure 2 The results mutually validated each other.

[0064] Example 3:

[0065] A method for preparing whey protein isolate-theabrownin complex aggregates includes the following steps:

[0066] a) Accurately weigh 1.00 g of commercially available whey protein isolate using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the whey protein isolate aqueous solution is 10 mg / mL.

[0067] b) Accurately weigh 1.00 g of commercially available theabrownin using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the theabrownin aqueous solution is 10 mg / mL.

[0068] c) Prepare whey protein isolate-theabrownin mixed solutions by mixing the above 10 mg / mL whey protein isolate aqueous solution and 10 mg / mL theabrownin aqueous solution at volume ratios of 15:1, 10:1, and 5:1 respectively.

[0069] d) Adjust the pH of the above whey protein isolate-theabrownin mixed solution to the range of 7.0 to 2.0 with hydrochloric acid. Take a sample of the mixed solution and place it in an ELISA plate for every 0.2 decrease in pH, and measure its turbidity at 600 nm.

[0070] e) In the above steps, take a mixed solution every 0.5 or 1 pH value, dilute it 10 times with distilled water of the same pH, and then use a laser diffraction nanoparticle size analyzer to detect its particle size and potential.

[0071] The results showed that, under room temperature conditions (25℃), the turbidity values ​​of the above-mentioned whey protein isolate-theabrownin mixed solution at different pH values ​​were as follows: Figure 4 As shown. The particle size and potential results of the above whey protein isolate-theabrownin mixed solution at different pH values ​​are as follows. Figure 5 As shown. Figure 4 This indicates that the turbidity value of the solution is related to the mixing ratio. As the mixing ratio increases, the maximum turbidity value first increases and then decreases, reaching its maximum at a mixing ratio of 10:1. At this ratio, the formed composite coagulants are the most abundant and stable. Figure 5 The results show that as the blending ratio increases, the pH values ​​at which the solution potential reaches zero and where the particle size is largest all shift towards higher pH values, promoting the formation of complex aggregates. Combining the two figures, when the whey protein isolate to theaflavins blending ratio increases from 5:1 to 10:1, the turbidity value is significantly higher at higher blending ratios. This is because a higher whey protein isolate / theaflavins ratio provides more whey protein isolate for binding with theaflavins, resulting in more and faster formation of complex aggregates. However, when the blending ratio continues to rise to 15:1, the turbidity value in the region where complex aggregates form decreases compared to the 10:1 ratio. This is because at a blending ratio of 10:1, the binding of whey protein isolate and theaflavins reaches saturation, the electrostatic interaction is strongest, and the most stable complex aggregates are formed.

[0072] Example 4:

[0073] A method for preparing whey protein isolate-theabrownin complex aggregate includes the following steps:

[0074] a) Accurately weigh 1.00 g of commercially available whey protein isolate using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the whey protein isolate aqueous solution is 10 mg / mL.

[0075] b) Accurately weigh 1.00 g of commercially available theabrownin using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the theabrownin aqueous solution is 10 mg / mL.

[0076] c) Prepare a whey protein isolate-theabrownin mixed solution by mixing the above 10 mg / mL whey protein isolate aqueous solution and 10 mg / mL theabrownin aqueous solution at a volume ratio of 10:1.

[0077] d) Adjust the pH of the above whey protein isolate-theabrownin mixed solution to 6.5, 5.5, 4.5, 3.5 and 2.5 with hydrochloric acid. Take a portion of the mixed solution at each pH value and add it to the ELISA plate. Use a multi-functional ELISA reader to detect the fluorescence spectrum with an excitation wavelength of 280 nm and a detection range of 300-450 nm.

[0078] Fluorescence spectra of whey protein isolate-theabrownin complex aggregates at different pH values ​​are as follows: Figure 6 As shown, the quenching effect of theaflavins on whey protein isolate first increases and then decreases as the pH value decreases, with the strongest quenching effect at pH 5.5, indicating that whey protein isolate and theaflavins bind more tightly at this pH.

[0079] Example 5:

[0080] A method for preparing whey protein isolate-theabrownin complex aggregate includes the following steps:

[0081] a) Accurately weigh 1.00 g of commercially available whey protein isolate using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the whey protein isolate aqueous solution is 10 mg / mL.

[0082] b) Accurately weigh 1.00 g of commercially available theabrownin using an analytical balance and dissolve it in 100 mL of water. At this point, the concentration of the theabrownin aqueous solution is 10 mg / mL.

[0083] c) Prepare a whey protein isolate-theabrownin mixed solution by mixing the above 10 mg / mL whey protein isolate aqueous solution and 10 mg / mL theabrownin aqueous solution at a volume ratio of 10:1.

[0084] d) Adjust the pH of the above whey protein isolate-theabrownin mixed solution to 5.5 with hydrochloric acid to obtain soluble whey protein isolate-theabrownin complex aggregate.

[0085] e) Freeze-dry the sample from step d.

[0086] f) After sputtering gold onto the freeze-dried sample from step f, observe it under a scanning electron microscope.

[0087] The results are as follows Figure 7As shown, the whey protein isolate-theabrownin complex aggregates are in the form of lumps and rods. The edges are relatively smooth, indicating that the two are relatively tightly bound.

[0088] Example 6

[0089] a) After sputtering gold onto the raw materials theabrownin and whey protein isolate powder samples, they were observed under a scanning electron microscope.

[0090] The results are as follows: Figure 8 , 9 As shown, both theaflavins and whey protein isolates are spherical structures with a particle size of approximately 50 nm.

[0091] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for the preparation of a complex coacervate based on whey protein isolate and theaflavins, characterized in that, The method comprises the following steps: S1, dissolving whey protein isolate to obtain a whey protein isolate aqueous solution, and dissolving the thearubin to obtain a thearubin aqueous solution; S2, mixing the whey protein isolate aqueous solution and the thearubin aqueous solution obtained in step S1 to obtain a whey protein isolate-thearubin mixed solution; S3, adding hydrochloric acid to the whey protein isolate-thearubin mixed solution obtained in step S2 to obtain a whey protein isolate-thearubin composite coacervate; In step S1, the concentration of the whey protein isolate aqueous solution is 10 mg / mL; and the concentration of the thearubin aqueous solution is 10 mg / mL; In step S1, the number average molecular weight of the thearubin and the whey protein isolate is 30-70 kilodaltons; In step S2, the mixing volume ratio of the whey protein isolate aqueous solution to the thearubin aqueous solution is 10:1; In step S3, after adding hydrochloric acid to the whey protein isolate-thearubin mixed solution, the pH is adjusted to be greater than 5.4 and less than 5.6; at this time, the thearubin and the whey protein isolate begin to aggregate to form a soluble composite coacervate; In step S3, sodium chloride is also used to adjust the ionic strength of the whey protein isolate-thearubin mixed solution to be 0-25 mM.

2. A process for the preparation of a complex coacervate based on whey protein isolate and theaflavins according to claim 1, characterized in that, In step S3, the shape of the whey protein isolate-thearubin composite coacervate obtained includes block and rod.

3. A whey protein isolate-thearubin composite coacervate obtained by the preparation method according to any one of claims 1-2.

4. Use of the whey protein- theabromine complex coagulate of claim 3, characterized in that, The whey protein isolate-thearubin composite coacervate is used for preparing food. The whey protein isolate-thearubin composite coacervate is used for preparing food.

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