High-concentration high-freeze-thaw-stability soybean protein gel and preparation method thereof

Abstract

The invention discloses high-concentration high-freeze-thaw-stability soybean protein gel and a preparation method thereof, and relates to the technical field of gel preparation. Compared with the existing preparation method of the soybean protein gel, the method disclosed by the invention mainly comprises the following two steps: 1) mixing soybean protein serving as a raw material with an alkali / acidic glyceryl solvent; and 2) uniformly mixing, heating, cooling and refrigerating to obtain the soybean protein gel. The preparation method has the advantages that 1, the soybean protein gel prepared through glyceryl solvent treatment has relatively high freeze-thaw stability, still has a complete and uniform gel form even after 20 times of freeze-thaw cycles, and is high in gel hardness; and 2, the protein concentration in the soybean protein gel prepared by the method can be up to 20% or above. And 3, the preparation method is simple, convenient, green and environment-friendly, a cross-linking agent does not need to be added, and the protein gel is non-toxic and edible and can be applied to the field of food.

Description

Technical Field

[0001] This invention relates to the field of gel preparation technology, specifically to a high-concentration, high-freeze-thaw-stability soybean protein gel and its preparation method. Background Technology

[0002] Soy protein isolate (SPI) is a high-purity plant protein made from defatted soybeans. It boasts advantages such as high nutritional value, good biocompatibility, and low cost. As an important raw material in the food industry, it is widely used in soy products, meat products, and beverages to improve food quality, such as enhancing texture, increasing elasticity, and improving water retention. Gel is one of its important application forms in food processing.

[0003] In the preparation of protein gels, protein concentration is the core factor regulating the gel network structure and functional properties, directly determining whether a gel can form and the physicochemical properties and application value of the gel after formation. However, soybean protein has poor solubility and is difficult to spontaneously form a gel in a typical aqueous system. Current solutions mainly employ methods such as enzyme treatment, cross-linking agents (natural / synthetic), physical induction, or a combination of these methods to promote coagulation. These methods not only have many drawbacks, including cumbersome procedures, high costs, and questionable safety, but also have little effect on protein solubilization. Furthermore, using acidic or alkaline solutions to improve protein solubility can significantly affect the protein's molecular structure, making it difficult to form a structurally stable, high-concentration gel system. Therefore, the current concentration of soybean protein isolate gel is around 10%.

[0004] Meanwhile, the freeze-thaw stability of protein gels is crucial for their application in frozen foods and other frozen environments. During the freeze-thaw cycle, phenomena such as water redistribution, ice crystal formation, and recrystallization affect the interactions between and within protein molecules, thereby disrupting the gel's ordered network structure. This leads to shrinkage, hardening, and reduced water-holding capacity, resulting in deterioration of product quality.

[0005] Therefore, developing a soybean protein gel with high concentration and high freeze-thaw stability can enhance the nutritional function of the gel and expand its application in frozen foods and other frozen environments. Summary of the Invention

[0006] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a method for preparing high-concentration, high-freeze-thaw-stability soybean protein gel, which effectively solves the problems of low protein content and quality deterioration during the freezing-thawing process of soybean protein gel, and provides a new solution for the preparation of high-concentration, high-freeze-thaw-stability soybean protein gel.

[0007] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing high-concentration, high-freeze-thaw-stability soybean protein gel, comprising the following steps: Glycerol, alkali or acid are heated and mixed with water to obtain an alkaline glycerol-based solvent or an acidic glycerol-based solvent. Soy protein and the alkaline glycerol-based solvent or the acidic glycerol-based solvent are mixed evenly to obtain a mixture; the mixture is heated and then cooled to obtain the soybean protein gel.

[0008] In a preferred embodiment of the present invention, the soy protein gel is obtained by mixing soy protein (mass concentration of 10%~30%) and an alkaline / acidic glycerol-based solvent using a magnetic stirrer at a speed of 300-700 rpm for 5-20 min, followed by heating in a 90°C water bath for 30 min, cooling to room temperature, and then refrigerating at 4°C for 24 h. The glycerol-based solvent is prepared by reacting glycerol, an alkaline / acidic solvent, and water; the soy protein is soy protein isolate.

[0009] In a preferred embodiment of the present invention, the alkali is potassium carbonate and the acid is DL-malic acid.

[0010] In a preferred embodiment of the present invention, the molar ratio of glycerol, alkali and water in the alkaline glycerol-based solvent is 7~10 : 0.4~3.8 : 12~13.

[0011] In a preferred embodiment of the present invention, the molar ratio of glycerol, acid and water in the acidic glycerol-based solvent is 0.5~3 : 0.4~3.8 : 4~5.

[0012] In a preferred embodiment of the present invention, the method of heating and mixing glycerol, alkali or acid with water includes: Glycerin, alkali or acid and water are placed in a water bath at 80-90 ℃ and stirred at 500-700 rpm for 30-60 minutes. The final system is clear and transparent, which is the alkaline glycerol-based solvent or acidic glycerol-based solvent.

[0013] In a preferred embodiment of the present invention, the mass concentration of soybean protein in the mixture is 10% to 30%.

[0014] In a preferred embodiment of the present invention, the method for uniformly mixing soybean protein and the alkaline glycerol-based solvent or the acidic glycerol-based solvent includes: Soy protein and the alkaline or acidic glycerol solvent are stirred and mixed for 5-20 minutes using a magnetic stirrer at a speed of 300-700 rpm.

[0015] In a preferred embodiment of the present invention, the heat treatment method includes heating at 90°C for 30 min.

[0016] Secondly, the present invention provides a high-concentration, high-freeze-thaw-stability soybean protein gel, which is obtained by the preparation method described above.

[0017] In a preferred embodiment of the present invention, the soybean protein gel retains an intact and uniform gel morphology after 20 freeze-thaw cycles, and the gel hardness is greater than 1000g.

[0018] This invention has at least one of the following beneficial effects: 1) The solvent raw materials used in this invention are widely available, inexpensive, safe and edible, and the prepared protein gel has excellent stability.

[0019] 2) The present invention can obtain a uniform and stable protein gel by mixing the solvent with the protein raw material and heating it. It does not require the complicated experimental steps in the traditional preparation method, nor does it require the use of additional cross-linking agents. The preparation method is simple and efficient.

[0020] 3) The protein concentration in the soybean protein gel obtained by this invention can be as high as 30%, and it has good freeze-thaw stability. It can not only meet the nutritional requirements of high protein, but also adapt to the application scenarios of low temperature freezing, thus expanding the application range of protein gel, such as in foods with long shelf life and low storage temperature.

[0021] In summary, the method of this invention is efficient, simple, green and environmentally friendly, and the resulting gel has good stability. Its feature is that it not only achieves the preparation of uniform protein gel under high concentration conditions, but also the gel has high freeze-thaw stability, which can be used in the field of frozen food. Attached Figure Description

[0022] Figure 1 The images show the protein gel samples prepared in Examples 1-2 and Comparative Example 1, and their physical images after 20T freeze-thaw cycles.

[0023] Figure 2 The images show the actual samples of protein gels prepared in Examples 1-2 and Comparative Examples 1-8.

[0024] Figure 3 The images show actual samples of the alkaline / acidic glycerol-based solvents used in Examples 1-2 and Comparative Examples 9-12. Detailed Implementation

[0025] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0026] A method for preparing a high-concentration, high-freeze-thaw-stability soybean protein gel includes the following steps: (1) Preparation of glycerol-based solvent: In the alkaline glycerol-based solvent, the molar mass of glycerol is 7-10 mol, the molar mass of the base is 0.4-3.8 mol, and the molar mass of water is 12-13 mol; in the acidic glycerol-based solvent, the molar mass of glycerol is 0.5-3 mol, the molar mass of the acid is 0.4-3.8 mol, and the molar mass of water is 4-5 mol. Glycerol, base / acid, and water are placed in an 80-90℃ water bath and stirred at 500-700 rpm for 30-60 min until the system is clear and transparent.

[0027] (2) Soy protein (mass concentration of 10%~30%) and alkaline / acidic glycerol-based solvent were mixed by stirring with a magnetic stirrer at a speed of 300-700 r / min for 5-20 min. After mixing, the mixture was heated at 90 ℃ for 30 min, cooled to room temperature, and refrigerated at 4 ℃ for 24 h to obtain protein gel.

[0028] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following specific embodiments.

[0029] Example 1 A method for preparing a soybean protein gel with high freeze-thaw stability includes the following steps: (1) Preparation of alkaline glycerol-based solvent: The molar ratio of glycerol, potassium carbonate and water is 8:1:12.2. Glycerol, potassium carbonate and water are stirred in a water bath at 80 °C for 30 min at a speed of 500 rpm to obtain alkaline glycerol-based solvent. The pH of the obtained solvent is 12.49.

[0030] (2) Mix soybean protein and alkaline glycerol solvent at a mass ratio of 20:80, and stir at 700 rpm for 5 min at room temperature to obtain a mixed sample.

[0031] (3) The mixed sample in step (2) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain a soybean protein gel with high freeze-thaw stability.

[0032] Example 2 A method for preparing a soybean protein gel with high freeze-thaw stability includes the following steps: (1) Preparation of acidic glycerol-based solvent: The molar ratio of glycerol, DL-malic acid and water is 2:1:4.4. Glycerol, DL-malic acid and water are stirred in a water bath at 80 °C for 30 min at a speed of 500 rpm to obtain acidic glycerol-based solvent. The pH of the obtained solvent is 1.00.

[0033] (2) Mix soybean protein and acidic glycerol solvent at a mass ratio of 20:80, and then stir with a magnetic stirrer at 700 rpm for 5 min until the mixture is homogeneous to obtain a mixed sample.

[0034] (3) The mixed sample in step (2) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain a soybean protein gel with high freeze-thaw stability.

[0035] Comparative Example 1 The difference from Example 1 is that no alkaline glycerol-based solvent was added. The specific steps are as follows: (1) Mix soybean protein and water at a mass ratio of 20:80, and then stir with a magnetic stirrer at 700 rpm for 5 minutes until the mixture is homogeneous to obtain a mixed sample.

[0036] (2) The mixed sample in step (1) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain protein gel.

[0037] Comparative Example 2 The difference from Example 1 is that "adding an alkaline glycerol-based solvent" is replaced with "an aqueous solution with pH=12.49". The specific steps are as follows: (1) Mix soybean protein and an aqueous solution with pH=12.49 (prepared by adding sodium hydroxide to water to form an aqueous solution with pH=12.49) in a mass ratio of 20:80, and then stir with a magnetic stirrer at 700 rpm for 5 min until the mixture is homogeneous.

[0038] (2) The mixed sample in step (1) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain protein gel.

[0039] Comparative Example 3 The difference from Example 2 is that the "acidic glycerol-based solvent" is replaced with an "aqueous solution with pH=1.00". The specific steps are as follows: (1) Mix soybean protein and pH=1.00 aqueous solution (prepared by adding hydrochloric acid to water to form pH=1.00 aqueous solution) at a ratio of 20:80, and then stir with a magnetic stirrer at 700 rpm for 5 min until the mixture is homogeneous.

[0040] (2) The mixed sample in step (1) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain protein gel.

[0041] Comparative Example 4 The difference from Examples 1 and 2 is that only glycerol was added, without potassium carbonate or malic acid. The specific steps are as follows: (1) Preparation of glycerol solution: The molar ratio of glycerol to water is 8:12.2. Glycerol and water are stirred in a water bath at 80 °C for 30 min at a speed of 500 rpm to obtain glycerol solution.

[0042] (2) Mix soybean protein and glycerol solution at a mass ratio of 20:80, and stir at 700 rpm for 5 min at room temperature to obtain a mixed sample.

[0043] (3) The mixed sample in step (2) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain soybean protein gel.

[0044] Comparative Example 5 The difference from Example 1 is that "potassium carbonate" is replaced with "potassium hydroxide". The specific steps are as follows: (1) Preparation of alkaline glycerol-based solvent: The molar ratio of glycerol, potassium hydroxide and water is 8:1:12.2. Glycerol, potassium hydroxide and water are stirred in a water bath at 80 °C for 30 min at a speed of 500 rpm to obtain alkaline glycerol-based solvent. The pH of the obtained solvent is 13.42.

[0045] (2) Mix soybean protein and alkaline glycerol solvent at a mass ratio of 20:80, and stir at 700 rpm for 5 min at room temperature to obtain a mixed sample.

[0046] (3) The mixed sample in step (2) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain soybean protein gel.

[0047] Comparative Example 6 The difference from Example 2 is that "DL-malic acid" was replaced with "acetic acid". The specific steps are as follows: (1) Preparation of acidic glycerol-based solvent: The molar ratio of glycerol, acetic acid and water is 2:1:4.4. Glycerol, acetic acid and water are stirred in a water bath at 80 °C for 30 min at a speed of 500 rpm to obtain acidic glycerol-based solvent. The pH of the obtained solvent is 1.82.

[0048] (2) Mix soybean protein and acidic glycerol solvent at a mass ratio of 20:80, and then stir with a magnetic stirrer at 700 rpm for 5 min until the mixture is homogeneous to obtain a mixed sample.

[0049] (3) The mixed sample in step (2) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain soybean protein gel.

[0050] Comparative Example 7 The difference from Example 1 is that glycerin was not added. The specific steps are as follows: (1) The molar ratio of potassium carbonate to water is 1:12.2. Potassium carbonate and water are stirred in a water bath at 80 °C for 30 min at a speed of 500 rpm to obtain an aqueous solution of potassium carbonate. The pH of the obtained solvent is 13.65.

[0051] (2) Mix soybean protein and solvent at a mass ratio of 20:80, and then stir with a magnetic stirrer at 700 rpm for 5 min until the mixture is homogeneous to obtain a mixed sample.

[0052] (3) The mixed sample in step (2) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain soybean protein gel.

[0053] Comparative Example 8 The difference from Example 2 is that glycerin was not added. The specific steps are as follows: (1) The molar ratio of malic acid to water is 1:4.4. Malic acid and water are stirred in a water bath at 80 °C for 30 min at a speed of 500 rpm to obtain an aqueous solution of malic acid. The pH of the obtained solvent is 0.18.

[0054] (2) Mix soybean protein and solvent at a mass ratio of 20:80, and then stir with a magnetic stirrer at 700 rpm for 5 min until the mixture is homogeneous to obtain a mixed sample.

[0055] (3) The mixed sample in step (2) was placed in a water bath at 90 °C for 30 min and cooled to room temperature. Then it was refrigerated at 4 °C for 24 h to obtain soybean protein gel.

[0056] Comparative Example 9 The difference from the alkaline glycerol-based solvent preparation in Example 1 is that the amount of potassium carbonate added is increased. The specific steps are as follows: Preparation of alkaline glycerol-based solvent: The molar ratio of glycerol, potassium carbonate and water is 8:4:12.2. Glycerol, potassium carbonate and water are stirred in a water bath at 80 ℃ for 30 min at a speed of 500 rpm.

[0057] The other steps are the same as in Example 1.

[0058] Comparative Example 10 The difference from the preparation using acidic glycerol-based solvent in Example 2 is that the amount of DL-malic acid added is increased. The specific steps are as follows: Preparation of acidic glycerol-based solvent: The molar ratio of glycerol, DL-malic acid and water is 2:4:4.4. Glycerol, DL-malic acid and water are stirred in a water bath at 80 ℃ for 30 min at a speed of 500 rpm.

[0059] The other steps are the same as in Example 2.

[0060] Comparative Example 11 The difference from the alkaline glycerol-based solvent preparation in Example 1 is that sodium carbonate is used instead of potassium carbonate. The specific steps are as follows: Preparation of alkaline glycerol-based solvent: The molar ratio of glycerol, sodium carbonate and water is 8:1:12.2. Glycerol, sodium carbonate and water are stirred in a water bath at 80 °C for 30 min at a speed of 500 rpm.

[0061] The other steps are the same as in Example 1.

[0062] Comparative Example 12 The difference from the preparation of the acidic glycerol-based solvent in Example 2 is that lactic acid is used instead of DL-malic acid. The specific steps are as follows: Preparation of acidic glycerol-based solvent: The molar ratio of glycerol, lactic acid and water is 2:1:4.4. Glycerol, lactic acid and water are stirred in a water bath at 80 ℃ for 30 min at a speed of 500 rpm.

[0063] The other steps are the same as in Example 2.

[0064] Performance testing: The following performance tests were performed on the soybean protein gels prepared in the examples and comparative examples: (1) The textural properties of the soybean protein gels prepared in Examples 1 and 2 were tested: The textural properties of the protein gels were characterized using a TA-XT plus physical property analyzer (UK). The probe used was a P / 0.5R, with a pre-test speed of 1 mm / s, a test speed of 1 mm / s, and a post-test speed of 1 mm / s. The pressure was applied twice consecutively, with a deformation of 30% and a trigger force of 2 g.

[0065] (2) Freeze-thaw stability test of soybean protein gels prepared in Examples 1-2 and Comparative Example 1: The samples were frozen in a -80 ℃ freezer for 24 h, and then thawed at room temperature for 1 h after 24 h. The samples were then photographed and observed.

[0066] (3) Structural observation test of soybean protein gels prepared in Examples 1-2 and Comparative Examples 1-8: After refrigeration for 24 hours, the samples were placed at room temperature for 1 hour and then photographed for observation.

[0067] (4) The alkaline and acidic glycerol-based solvents prepared in Examples 1-2 and Comparative Examples 9-12 were subjected to physical state tests and photographed for observation.

[0068] Test results are as follows Figures 1-3 As shown in Table 1.

[0069] Figure 1 , Figure 2 Images of histone gels treated with different methods are shown. Figure 1 As can be seen, the water treatment group (Comparative Example 1) could not form a uniform protein gel, and after 20 freeze-thaw cycles, the gel shrank and deformed, and water precipitated on the inner wall of the sample vial; while the alkaline / acidic glycerol-based solvent treatment group (Examples 1-2) formed a uniform gel, and after 20 freeze-thaw cycles, the gel did not undergo significant changes in appearance.

[0070] from Figure 2 As can be seen, under the same pH and protein concentration (20%) as the glycerol-based solvent, Comparative Examples 2 and 3 failed to form a uniform gel. This indicates that the high freeze-thaw stability of soybean protein gel prepared by this invention is not due to the solubilizing effect of pH, but rather requires specific solvent composition and ratio. Comparative Examples 4, 5, and 6, which added glycerol and glycerol-based solvents prepared from other bases or acids, could form gels, but their structures were unstable. After refrigeration, they exhibited deterioration in quality, including water separation, flocculation, and shrinkage. This shows that using glycerol alone cannot achieve a stable high-concentration gel, and that glycerol, along with other types of acids and bases, also cannot achieve a stable high-concentration gel. Comparative Examples 7 and 8, which prepared gels by adding only the same concentration of potassium carbonate or malic acid, exhibited flocculent or clumpy structures and could not form a uniform and dense gel structure. This indicates that using these two alkaline salts or acids alone also cannot achieve a stable high-concentration gel. The alkaline / acidic glycerol-based solvent treatment group (Examples 1-2) in this method can form a dense, uniform, and stable soybean protein gel. The gel structure remains stable after refrigeration, without flocculation, water separation, or shrinkage. Comparative analysis reveals that the preparation method of the high-concentration, high-freeze-thaw-stability soybean protein gel provided by this invention is not based on the influence of existing solvent pH or glycerol on the solubilization and gelation properties of soybean protein, but rather on the synergistic effect of potassium carbonate / DL-malic acid and glycerol.

[0071] Figure 3The alkaline / acidic glycerol-based solvent obtained by the Nakamoto method is a transparent and homogeneous liquid at room temperature. However, when the ratio of potassium carbonate to DL malic acid is adjusted (Comparative Examples 9 and 10), or the type of alkaline or acid is changed (Comparative Examples 11 and 12), a homogeneous and transparent solvent system at room temperature cannot be obtained, and the effective dissolution of soybean protein cannot be achieved, thus failing to prepare soybean protein gel.

[0072] Therefore, under the condition of a protein concentration of 20% in the preparation system, compared with the protein gel samples in the alkaline / acidic glycerol-based solvent treatment group, the protein gel obtained by this method in the water treatment group, and the group treated with a solution of the same pH as the glycerol-based solvent, has a more uniform texture and can form complete and regularly shaped gels. Furthermore, compared with the water treatment group (… Figure 1 After 20 freeze-thaw cycles, the water-treated gels showed obvious edge shrinkage and textural collapse, but the alkaline / acidic glycerol-based solvent histone gels did not show obvious changes in appearance or water separation.

[0073] Table 1 illustrates the textural properties of the protein gels obtained by the alkaline / acidic glycerol-based solvent group in this method. The protein gels treated with glycerol-based solvents have higher hardness. When the soybean protein concentration is 20%, the hardness of the protein gels obtained by alkaline glycerol-based solvent treatment is 1051.90±8.77 g, and the hardness of the protein gels obtained by acidic glycerol-based solvent treatment is 1482.76±36.91 g.

[0074] Table 1. Texture properties of gel samples from different treatment groups Note: The water treatment group (Comparative Example 1) could not form a uniform protein gel, so its texture properties were not measured.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-concentration, high-freeze-thaw-stability soybean protein gel, characterized in that, Includes the following steps: Glycerol, alkali or acid are heated and mixed with water to obtain an alkaline glycerol-based solvent or an acidic glycerol-based solvent. Soy protein and the alkaline glycerol-based solvent or the acidic glycerol-based solvent are mixed evenly to obtain a mixture; the mixture is heated and then cooled to obtain the soybean protein gel.

2. The preparation method according to claim 1, characterized in that, The base is potassium carbonate, and the acid is DL-malic acid.

3. The preparation method according to claim 1, characterized in that, In the alkaline glycerol-based solvent, the molar ratio of glycerol, alkali, and water is 7~10 : 0.4~3.8 : 12~13.

4. The preparation method according to claim 1, characterized in that, In the acidic glycerol-based solvent, the molar ratio of glycerol, acid, and water is 0.5~3 : 0.4~3.8 : 4~5.

5. The preparation method according to claim 1, characterized in that, Methods for heating and mixing glycerol, alkali, or acid with water include: Glycerin, alkali or acid and water are placed in a water bath at 80-90 ℃ and stirred at 500-700 rpm for 30-60 min. The final system is clear and transparent, which is the alkaline glycerol-based solvent or acidic glycerol-based solvent.

6. The preparation method according to claim 1, characterized in that, The mass concentration of soybean protein in the mixture is 10% to 30%.

7. The preparation method according to claim 1, characterized in that, A method for uniformly mixing soybean protein with the alkaline glycerol-based solvent or the acidic glycerol-based solvent includes: Soy protein and the alkaline or acidic glycerol solvent are stirred and mixed for 5-20 minutes using a magnetic stirrer at a speed of 300-700 r / min.

8. The preparation method according to claim 1, characterized in that, The heat treatment method includes heating at 90°C for 30 minutes.

9. A high-concentration, high-freeze-thaw-stability soybean protein gel, characterized in that, It is obtained by the preparation method described in any one of claims 1 to 8.

10. The soybean protein gel according to claim 9, characterized in that, The soybean protein gel retains its complete and uniform gel morphology even after 20 freeze-thaw cycles, and its gel hardness is greater than 1000g.

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