Sodium caseinate-glutamine transaminase gel and preparation method thereof
By controlling the particle size and ionic strength of sodium caseinate solution, combined with physical modification and enzymatic reaction, the problem of unstable performance of sodium caseinate gel was solved, and a gel with excellent strength and water retention suitable for high value-added foods was prepared.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-21
- Publication Date
- 2026-04-07
AI Technical Summary
Sodium caseinate gels are unstable and difficult to form a dense, uniform three-dimensional network structure, which fails to meet the textural requirements of high-value-added protein products. Existing technologies lack systematic methods to optimize the sodium caseinate-TG enzyme system.
By preparing a sodium caseinate solution and performing physical modification treatments such as ultrasonic or high-pressure homogenization, the ionic strength and pH value are adjusted to form a protein suspension with a predetermined particle size distribution, which is then mixed with transglutaminase for an enzymatic gelation reaction.
It significantly improves the hardness, elasticity, and water retention of the gel, achieves precise control of the gelation process, and ensures good product quality uniformity. It is suitable for high-protein jellies, functional puddings, low-fat cheeses, plant-based meat products, and foods for those with swallowing difficulties, and is in line with the trend of clean labeling.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of food science and protein processing, and specifically relates to a sodium caseinate-glutamine transaminase gel and a preparation method thereof. BACKGROUND
[0002] Sodium caseinate is an important food protein raw material, which is widely used in dairy products, meat products and other foods due to its good emulsifying property, hydration property and the like. However, sodium caseinate itself has weak gelation. In recent years, the application of microbial glutamine transaminase (TGase) provides a new way for protein gel preparation. TGase can catalyze the formation of epsilon-(gamma-glutamyl) lysine isopeptide bonds between glutamine residues and lysine residues in proteins under mild conditions, catalyze the cross-linking between protein molecules, and form a covalent gel network, thereby significantly improving the texture properties, water holding capacity and stability of the protein. However, the proteins in the natural sodium caseinate solution exist in the form of micelles and other aggregation forms, the particle size distribution is wide and the aggregation state is not uniform, and it is significantly affected by the source of raw materials, production process and batch difference. This makes sodium caseinate not always suitable for TGase cross-linking, and it is difficult to form a dense and uniform three-dimensional network structure, thereby causing the instability of the strength, elasticity, water holding capacity, freeze-thaw stability and other properties of the final gel product, and it is difficult to meet the stringent requirements of high-value protein product development (such as high-protein jelly, dysphagia food, etc.) on texture.
[0003] In the prior art, the preparation of sodium caseinate gel mainly relies on acid-induced gelation (such as yogurt, cheese and the like) or heat-induced gelation (such as pudding, baking filling and the like). Although there are reports on the improvement of protein gel by adding polysaccharides (such as gellan gum, carrageenan and the like) or simple homogenization, or the introduction of exogenous additives, the problems of the unsuitability of the structure of sodium caseinate raw material itself for forming a gel with excellent performance and the inconsistency of the performance of enzyme-induced gel caused by the difference of raw materials have not been fundamentally solved. There are few reports on the systematic regulation of the components of sodium caseinate raw material itself, and there is a lack of a systematic method for optimizing the performance of the final gel by regulating the structure of protein precursors for the "sodium caseinate-TGase" system. SUMMARY
[0004] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification of the present application in order to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.
[0005] In view of the above and / or problems existing in the prior art, the present application is proposed.
[0006] Therefore, the present application aims to overcome the deficiencies of the prior art, and provides a sodium caseinate-glutamine transaminase gel and a preparation method thereof.
[0007] To solve the above technical problems, the present application provides a preparation method of a sodium caseinate-glutamine transaminase gel, comprising, configuring a sodium caseinate solution; physically modifying the sodium caseinate solution to regulate the protein aggregate structure in the solution and form a protein suspension with a predetermined particle size distribution and dispersity; mixing the protein suspension with glutamine transaminase to perform an enzymatic gel reaction.
[0008] As a preferred embodiment of the preparation method of the present application, the physical modification process includes one or more of ultrasonic treatment and high-pressure homogenization; the ultrasonic treatment has a power of 100-500 W and a time of 5-30 minutes; the high-pressure homogenization has a pressure of 20-100 MPa and a cycle number of 1-10.
[0009] As a preferred embodiment of the preparation method of the present application, the sodium caseinate solution is regulated in ionic strength and pH value before or after the physical modification process; the ionic strength of the sodium caseinate solution is regulated so that the sodium ion concentration is 50-250 mM; the pH value of the sodium caseinate solution is regulated to be 6.5-8.5.
[0010] As a preferred embodiment of the preparation method of the present application, the ionic strength is regulated by adding one or more of sodium chloride, sodium phosphate, and sodium citrate; the pH value is regulated by adding sodium hydroxide solution or hydrochloric acid solution.
[0011] As a preferred embodiment of the preparation method of the present application, the physical modification process aims to make the average particle size of the protein aggregates in the protein suspension 50-500 nm; and the polymer dispersity index is less than 2.0.
[0012] As a preferred embodiment of the preparation method of the present application, the average particle size of the protein aggregates in the protein suspension is 100-200 nm; and the polymer dispersity index is less than 0.5-1.0.
[0013] As a preferred embodiment of the preparation method of the present application, the concentration of the sodium caseinate solution is 7%-14% (w / w).
[0014] As a preferred embodiment of the preparation method of the present application, the enzyme addition amount in the enzymatic gel reaction is 20-500 U / g of protein.
[0015] As a preferred solution of the preparation method, the conditions of the enzymatic gel reaction are: reacting at 30-50℃ for 0.5-3 hours, and then heating at 70-90℃ for 10-20 minutes to inactivate the enzyme.
[0016] Still another object of the present application is to provide a sodium caseinate gel prepared by the preparation method.
[0017] The present application has the following advantages: The gel prepared by the present application has significantly improved performance: through pretreatment, the hardness, elasticity, chewiness and water holding capacity of the gel are systematically improved, overcoming the problem of unstable performance of natural sodium caseinate gel; by regulating the specific physicochemical parameters (particle size, PDI, ionic strength, pH), the gel process is precisely controlled, ensuring the uniformity of product quality; the obtained gel is very suitable for, for example, high-protein jelly, functional pudding, low-fat cheese, vegetarian meat products, dysphagia food and instant high-protein meals. Finally, the method used in the present application is physical and biological enzymatic method, without adding chemical cross-linking agent, which meets the clean label trend. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor. Among them: Figure 1 The protein aggregate morphology diagram of the modified examples and comparative examples observed by atomic force microscope for the embodiments of the present application. DETAILED DESCRIPTION
[0019] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail in the following with reference to the embodiment description.
[0020] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited to the specific embodiments disclosed below.
[0021] The raw materials used in the present application are all commercially available products unless otherwise specified.
[0022] The method for measuring the particle size distribution and zeta potential of the solution in the present application is: Reference (Liang G J, et al. Enhancing soy protein isolate gels: combined control of pH and surface charge for improved structural integrity and gel strength. Food Bioscience The method described in the reference (Liang G J, et al. Enhancing soy protein isolate gels: combined control of pH and surface charge for improved structural integrity and gel strength.
[0023] The method for observing the morphology of protein aggregates by atomic force microscopy used in the present application is as follows: Take 2 μg / mL sodium caseinate solution and drop it onto a clean mica sheet. After drying, observe the surface morphology of sodium caseinate aggregates using contact mode, with a scanning area of 20 x 20 μm² and 5 x 5 μm².
[0024] The method for measuring gel strength used in the present application is as follows: Use the texture analyzer TA-XT plus (Stable Micro Systems, UK) equipped with a P / 0.5R probe to test the gel. The test speed is 0.5 mm / s, and the trigger force is 5 g. The gel strength is expressed as the maximum force (in g) required for the probe to penetrate the gel 4 mm deep.
[0025] The method for measuring gel water holding capacity used in the present application is as follows: Use the centrifugal method to measure. Take oven-dried filter paper (recorded as mass m1) and lay it flat on the bottom of a 50 mL centrifuge tube. Weigh 2.000 g of gel sample (recorded as mass m2) on an analytical balance and carefully place it on the filter paper in the centrifuge tube. Place the centrifuge tube in the centrifuge and set the centrifuge parameters: speed 4000 rpm, time 15 minutes, temperature 25°C. After centrifugation, remove the gel residue on the filter paper with tweezers (avoiding loss), absorb the water on the surface of the gel, and place it together with the filter paper in an analytical balance (recorded as mass m3). Determine the water holding capacity of the sample according to the following formula (1).
[0026] Example 1 Example 1 provides a method for optimizing sodium caseinate-glutamine transaminase gel, specifically: (1) Configuration of sodium caseinate solution: Take 5 g of sodium caseinate powder, dissolve it in deionized water, and configure it into a 10% (w / w) solution, magnetically stir for 2 hours, and hydrate overnight in a 4°C refrigerator.
[0027] (2) Component regulation and physical modification: Adjust the pH value of the above sodium caseinate solution to 7.2; add sodium chloride to make its final concentration in the solution 150 mM, and magnetically stir until completely dissolved; place the solution in an ultrasonic cell disruptor, under the condition of 200W power and ice water bath cooling, ultrasonic treatment for 10 minutes (work for 2s, intermittent for 2s). Take the modified solution, and use a laser particle size analyzer to measure the protein particle size and zeta potential, the results are shown in Table 1.
[0028] (3) Enzymatic gel preparation: The TG enzyme addition amount in the enzymatic gel reaction is 100 U / g protein (based on protein mass as substrate), and it is quickly stirred uniformly. The mixed liquid is divided into cylindrical molds (diameter 30 mm, height 20 mm) and sealed with sealing film. Place it in a 40°C water bath for 1 hour for enzymatic crosslinking. Then transfer it to an 85°C water bath for 15 minutes to inactivate the enzyme. After taking it out, quickly cool it to room temperature, and store it in a 4°C refrigerator for 12 hours before measuring the gel performance, the results are shown in Table 1.
[0029] Example 2 (8%, enzyme activity 200 U / g) The difference between this example and Example 1 is the concentration of sodium caseinate solution in step (1) and the concentration of TG enzyme activity in step (3), specifically: (1) Configuration of sodium caseinate solution: Take 5 g of sodium caseinate powder, dissolve it in deionized water, and magnetically stir for 2 hours to configure an 8% (w / w) solution, and hydrate it overnight in a 4°C refrigerator.
[0030] (3) Enzymatic gel preparation: The TG enzyme addition amount in the enzymatic gel reaction is 200 U / g protein (based on protein mass as substrate), and it is quickly stirred uniformly.
[0031] The rest of the preparation method is consistent with Example 1, and the sodium caseinate-TG enzyme gel of this example is obtained.
[0032] Example 3 (12%, enzyme activity 500 U / g) The difference between this example and Example 1 is the concentration of sodium caseinate solution in step (1) and the concentration of TG enzyme activity in step (3), specifically: (1) Preparation of sodium caseinate solution: Weigh 5 g of sodium caseinate powder, dissolve it in deionized water, and magnetically stir for 2 hours to prepare a 12% (w / w) solution. Hydrate overnight in a 4°C refrigerator.
[0033] (3) Enzymatic gel preparation: The amount of TGase added in the enzymatic gel reaction is 500 U / g of protein (based on the mass of protein as substrate), and it is uniformly stirred quickly.
[0034] The remaining preparation method is consistent with that of Example 1, and the sodium caseinate-TGase gel of this example is obtained.
[0035] Example 4 (pH 6.8, ion concentration, ultrasonic time) The difference between this example and Example 1 is the component regulation and physical modification method in step (2), which is as follows: (2) Component regulation and physical modification: Adjust the pH of the above sodium caseinate solution to 6.8; add sodium chloride to make the final concentration in the solution 50 mM, and magnetically stir until completely dissolved; place the solution in an ultrasonic cell disruptor, and under the conditions of 200 W power and ice water cooling, ultrasonic treatment for 15 minutes (work for 2 s, intermittent for 2 s). Take a small amount of the modified solution, and measure the protein particle size and ζ-potential with a laser particle size analyzer. The results are shown in Table 1.
[0036] The remaining preparation method is consistent with that of Example 1, and the sodium caseinate-TGase gel of this example is obtained.
[0037] Example 5 (pH 7.5, ion type and concentration, high-pressure homogenization) The difference between this example and Example 1 is the component regulation and physical modification method in step (2), which is as follows: (2) Component regulation and physical modification: Adjust the pH of the above sodium caseinate solution to 7.5; add sodium citrate to make the final concentration in the solution 100 mM, and magnetically stir until completely dissolved; subject the solution to high-pressure homogenization treatment, and homogenize it for 3 cycles under a pressure of 60 MPa. Take a small amount of the modified solution, and measure the protein particle size and ζ-potential with a laser particle size analyzer. The results are shown in Table 1.
[0038] The remaining preparation method is consistent with that of Example 1, and the sodium caseinate-TGase gel of this example is obtained.
[0039] Example 6 (pH 8.0, ion type and concentration, high-pressure homogenization) The difference between this embodiment and embodiment 1 is the component regulation and physical modification method in step (2), specifically: (2) Component regulation and physical modification: The pH value of the above sodium caseinate solution was adjusted to 8.0; sodium phosphate was added to make the final concentration in the solution 200 mM, and magnetic stirring was performed until complete dissolution; the solution was subjected to high-pressure homogenization, and was homogenized once at a pressure of 100 MPa. A small amount of the modified solution was taken, and the protein particle size and zeta potential were determined by a laser particle size analyzer, and the results are shown in Table 1.
[0040] The remaining preparation method was consistent with that of embodiment 1, and the sodium caseinate-TGase gel of this embodiment was obtained.
[0041] Example 7 (pH 7.0, ion concentration, high-pressure homogenization + ultrasonic) The difference between this embodiment and embodiment 1 is the component regulation and physical modification method in step (2), specifically: (2) Component regulation and physical modification: The pH value of the above sodium caseinate solution was adjusted to 7.0; sodium chloride was added to make the final concentration in the solution 100 mM, and magnetic stirring was performed until complete dissolution; the solution was first subjected to high-pressure homogenization, and was homogenized once at a pressure of 100 MPa, and then was subjected to ultrasonic treatment (300 W, 10 min). A small amount of the modified solution was taken, and the protein particle size and zeta potential were determined by a laser particle size analyzer, and the results are shown in Table 1.
[0042] The remaining preparation method was consistent with that of embodiment 1, and the sodium caseinate-TGase gel of this embodiment was obtained.
[0043] Example 8 (pH 7.2, no salt, ultrasonic power and time) The difference between this embodiment and embodiment 1 is the component regulation and physical modification method in step (2), specifically: (2) Component regulation and physical modification: The pH value of the above sodium caseinate solution was adjusted to 7.2; no salt was added, so that the ionic strength was lower than that in the other embodiments; the solution was placed in an ultrasonic cell disruptor, and was subjected to ultrasonic treatment under the condition of 100 W power and ice water bath cooling for 30 min (working for 2 s, and intermittent for 2 s). A small amount of the modified solution was taken, and the protein particle size and zeta potential were determined by a laser particle size analyzer, and the results are shown in Table 1.
[0044] The remaining preparation method was consistent with that of embodiment 1, and the sodium caseinate-TGase gel of this embodiment was obtained.
[0045] Example 9 (water bath for 3 h, enzyme inactivation condition for 30 min) The difference between this example and Example 1 is the enzymatic condition in step (3), specifically: (3) Enzymatic gel making: To 100 g of the modified protein solution, 0.5 g (about 0.5% based on the mass of protein as substrate) of TGase (100 U / g) was added and mixed well by rapid stirring. The mixture was divided into cylindrical molds (diameter 30 mm, height 20 mm) and sealed with sealing film. It was placed in a 35°C water bath for 3 hours for enzymatic crosslinking. Then it was transferred to a 70°C water bath for 30 minutes to inactivate the enzyme. After removal, it was quickly cooled to room temperature and stored in a 4°C refrigerator for 12 hours before measuring the gel properties. The results are shown in Table 1.
[0046] The rest of the preparation method is consistent with Example 1, and the sodium caseinate-TGase gel of this example is obtained.
[0047] Comparative Example 1 (without any modification) The difference between this comparative example and Example 1 is that there is no component regulation and physical modification in step (2), specifically: The sodium caseinate solution (pH 6.8) prepared and hydrated overnight in step (1) was directly mixed with TGase to perform the enzymatic gel reaction in step (3).
[0048] The rest of the preparation method is consistent with Example 1, and the sodium caseinate-TGase gel of this comparative example is obtained.
[0049] Comparative Example 2 (only physical modification, no pH / ion regulation) The difference between this comparative example and Example 1 is that only physical modification is performed in step (2) without pH / ion regulation, specifically: The sodium caseinate solution in step (1) was placed in an ultrasonic cell disruptor and treated with ultrasound for 10 minutes (working for 2 s, intermittent for 2 s) at a power of 200 W with ice water cooling. A small amount of the modified solution was taken and the protein particle size and zeta potential were measured with a laser particle size analyzer. The results are shown in Table 1.
[0050] The rest of the preparation method is consistent with Example 1, and the sodium caseinate-TGase gel of this example is obtained.
[0051] Comparative Example 3 (only pH / ion regulation, no physical modification) The difference between this comparative example and Example 1 is that only pH / ion regulation is performed in step (2) without physical modification, specifically: The pH of the sodium caseinate solution of step (1) was adjusted to 7.2; sodium chloride was added to a final concentration of 150 mM in the solution, and magnetic stirring was performed until complete dissolution; a small amount of the modified solution was taken, and the particle size and zeta potential of the protein were determined by a laser particle size analyzer, and the results are shown in Table 1.
[0052] The remaining preparation method was consistent with that of Example 1, and a sodium caseinate-TG enzyme gel of this example was obtained.
[0053] Comparative Example 4 (physical modification parameters out of range: ultrasonic power too low) The difference between this comparative example and Example 1 is the component regulation and physical modification method in step (2), specifically: The pH of the sodium caseinate solution of step (1) was adjusted to 7.2; sodium chloride was added to a final concentration of 150 mM in the solution, and magnetic stirring was performed until complete dissolution; the solution was placed in an ultrasonic cell disruptor, and ultrasonic treatment was performed at 50 W power and under ice water cooling conditions for 10 minutes (working for 2 s, and intermittent for 2 s). A small amount of the modified solution was taken, and the particle size and zeta potential of the protein were determined by a laser particle size analyzer, and the results are shown in Table 1.
[0054] Comparative Example 5 (pH out of the optimal range: too low 6.0) The difference between this comparative example and Example 1 is the component regulation and physical modification method in step (2), specifically: The pH of the sodium caseinate solution of step (1) was adjusted to 6.0; sodium chloride was added to a final concentration of 150 mM in the solution, and magnetic stirring was performed until complete dissolution; the solution was placed in an ultrasonic cell disruptor, and ultrasonic treatment was performed at 200 W power and under ice water cooling conditions for 10 minutes (working for 2 s, and intermittent for 2 s). A small amount of the modified solution was taken, and the particle size and zeta potential of the protein were determined by a laser particle size analyzer, and the results are shown in Table 1.
[0055] Comparative Example 6 (ion strength too high 400 nm) The difference between this comparative example and Example 1 is the component regulation and physical modification method in step (2), specifically: The pH of the sodium caseinate solution of step (1) was adjusted to 7.2; sodium chloride was added to a final concentration of 400 mM in the solution, and magnetic stirring was performed until complete dissolution; the solution was placed in an ultrasonic cell disruptor, and ultrasonic treatment was performed at 200 W power and under ice water cooling conditions for 10 minutes (working for 2 s, and intermittent for 2 s). A small amount of the modified solution was taken, and the particle size and zeta potential of the protein were determined by a laser particle size analyzer, and the results are shown in Table 1.
[0056] The gels prepared in Examples 1-9 and Comparative Examples 1-6 were subjected to performance testing, and the results are shown in Table 1.
[0057] Table 1 Aggregation and gel properties of protein solution
[0058] As can be seen from Table 1, compared with Comparative Examples 1-6, the average particle size and PDI index of the protein solution of Examples 1-9 are significantly reduced, which indicates that the optimization of components and physical modification significantly reduce the particle size, the sodium caseinate aggregates are more uniformly distributed, which is more conducive to enzymatic cross-linking, and thus the final gel strength is higher than that of the comparative examples. Figure 1 As can be seen from the atomic force microscope (AFM), the sodium caseinate of the comparative examples forms larger aggregates, which has a negative effect on the subsequent formation of the enzymatic gel, because the greater the difference in the shape and size of individual sodium caseinate particles, the smaller the contact area and the possibility of contact between the particles, resulting in low density of the formed gel. Due to the optimization of the components, the sodium caseinate aggregates of the examples are in a state of different degrees of depolymerization, and the contactability between the particles is greatly increased, which lays a spatial foundation for the reaction of TG enzyme.
[0059] Specifically, from the protein concentration, the higher the concentration of sodium caseinate in Examples 1-3, the stronger the gel strength; from the pH regulation, when the pH is between 7.0-7.5, the gel strength is generally higher, which may be due to the fact that the activity of TG enzyme is stronger at this pH range, and its ability to cross-link proteins is stronger, and in addition to the optimization of components and physical modification, the sodium caseinate aggregates are more uniformly distributed, which is more conducive to enzymatic cross-linking, and its gel capacity is greatly improved. At a sodium caseinate addition amount of 10%, Example 7 uses high-pressure homogenization combined with ultrasonic to perform physical modification, achieving a synergistic effect, and the gel strength is significantly higher than that of other examples and comparative examples. Comparative Example 5 has a too low pH value close to the isoelectric point of sodium caseinate, resulting in protein precipitation and aggregation, reducing the contact sites with TG enzyme, and failing to form a good gel network, so that the gel cannot be formed and has poor water holding capacity. Comparative Example 6 has a too high ionic strength, resulting in salting-out effect, and a large amount of protein is precipitated, which also cannot react with TG enzyme to form a good gel network, so that the gel cannot be formed and has poor water holding capacity.
[0060] In summary, the present application significantly optimizes the TG enzymatic gel properties of sodium caseinate through a specific processing process, and provides an effective technical solution for the development of high-quality protein gel products.
[0061] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, which should be covered by the scope of the claims of the present application.
Claims
1. A method for preparing sodium caseinate-glutamine transaminase gel, characterized in that: include, Prepare sodium caseinate solution; The sodium caseinate solution was physically modified to regulate the structure of protein aggregates in the solution and form a protein suspension with a predetermined particle size distribution and dispersibility. The protein suspension was mixed with transglutaminase and subjected to an enzymatic gelation reaction.
2. The preparation method according to claim 1, characterized in that: The physical modification treatment includes one or more of ultrasonic treatment and high-pressure homogenization treatment; wherein the ultrasonic treatment has a power of 100-500W and a time of 5-30 minutes; the high-pressure homogenization treatment has a pressure of 20-100 MPa and a cycle number of 1-10 times.
3. The preparation method according to claim 2, characterized in that: Before or after physical modification treatment, the ionic strength and pH of the sodium caseinate solution are adjusted; the ionic strength of the sodium caseinate solution is adjusted so that the sodium ion concentration is 50-250 mM; the pH of the sodium caseinate solution is adjusted to 6.5-8.
5.
4. The preparation method according to claim 3, characterized in that: Ionic strength can be adjusted by adding one or more of sodium chloride, sodium phosphate, and sodium citrate; pH value can be adjusted by adding sodium hydroxide solution or hydrochloric acid solution.
5. The preparation method according to claim 1, characterized in that: The objective of the physical modification treatment is to make the average particle size of the protein aggregates in the protein suspension 50-500 nm and its polymer dispersibility index less than 2.
0.
6. The preparation method according to claim 5, characterized in that: The average particle size of the protein aggregates in the protein suspension is 100-200 nm; its polymer dispersibility index is less than 0.5-1.
0.
7. The preparation method according to claim 1, characterized in that: The concentration of the sodium caseinate solution is 7%-14% (w / w).
8. The preparation method according to claim 1, characterized in that: The amount of enzyme added in the enzymatic gelation reaction is 20-500 U / g protein.
9. The preparation method according to claim 1, characterized in that: The conditions for the enzymatic gelation reaction are: reaction at 30-50℃ for 0.5-3 hours, followed by heating at 70-90℃ for 10-20 minutes to inactivate the enzyme.
10. Sodium caseinate gel prepared by any of the preparation methods described in claims 1-9.