Method for improving tensile property of soybean protein amyloid fiber hydrogel based on pressing method

Abstract

The invention discloses a method for improving the tensile property of soybean protein amyloid fiber hydrogel based on a pressing method, and belongs to the technical field of improvement of protein functional characteristics. The method comprises the following steps: (1) preparing soybean protein amyloid fibers; and (2) preparing the soybean protein amyloid fiber hydrogel. According to the preparation method disclosed by the invention, the dual-network hydrogel is successfully prepared by adjusting the pH value of the soybean protein amyloid fiber and mixing the soybean protein amyloid fiber with the sodium alginate and the calcium chloride. After compression treatment, the hydrogel shows excellent stretchability, and the stretch rate can reach 91.2%. The research provides theoretical guidance for improving the gel forming performance of the soybean protein amyloid fiber and improving the extremely acidic environment of the soybean protein amyloid fiber, which is crucial for expanding the application of the soybean protein amyloid fiber in industrial food application.

Description

Technical Field

[0001] This invention belongs to the food field and mainly relates to a method for improving the tensile properties of soybean protein starch-like fiber hydrogel by compression. Background Technology

[0002] Soy protein isolate offers significant advantages in enhancing human health and promoting environmental sustainability. In the food industry, soy protein has garnered significant attention due to its rich nutritional value, low cost, biodegradability, and various functionalities (such as gelling, emulsifying, foaming, water-holding, and oil-absorbing properties). Under high temperature and acidic conditions, soy protein isolate exhibits a tendency to self-assemble, thus forming a fibrous structure harmless to human cells.

[0003] The formation of three-dimensional hydrogel networks is achieved through the cross-linking of hydrophilic polymer chains, exhibiting significant water absorption and swelling capabilities. Because hydrogels can absorb and retain large amounts of water while maintaining the integrity of their overall structure, they hold immense potential for widespread application in the food industry, biomedicine, tissue engineering, and other fields. Polysaccharides and proteins are ideal materials for creating food gels with unique textures. Compared to single biopolymer systems, mixtures of these materials can better leverage their respective advantages, facilitating the design of multi-structured food gels.

[0004] Soy protein amyloid fibers are highly ordered, cross-beta structures formed through the fibrillation of globular proteins, exhibiting excellent gelling properties. As a representative component, soy protein amyloid fibers have been proven non-toxic to human cells, ensuring their safety for use in the food industry. Soy protein amyloid fibers possess excellent stiffness, extensibility, and thermodynamic stability, and offer a more favorable structure compared to soy protein isolate.

[0005] This invention successfully prepared a dual-network hydrogel by adjusting the pH value of soybean amyloid fibers and mixing them with sodium alginate and calcium chloride. After compression treatment, the hydrogel exhibited excellent stretchability. This research provides theoretical guidance for improving the gel-forming properties of soybean amyloid fibers and mitigating their highly acidic environment, which is crucial for expanding the application of soybean amyloid fibers in industrial food processing. Summary of the Invention

[0006] This invention provides a method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression. This method has the advantages of simple operation and low cost, and can effectively prepare stretchable soybean protein amyloid fiber hydrogel.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solution:

[0008] A method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression, characterized by the following steps:

[0009] Step 1: Preparation of Soybean Amyloid Fiber: A soybean protein stock solution was prepared by dispersing soybean protein powder in deionized water and gently stirring for 10 hours. After centrifugation at 10000×g, a homogeneous suspension was obtained, free of fine, insoluble soybean protein solid particles. The pH was adjusted to 2.0 with HCl (6M). Under culture conditions, the solution was continuously stirred at 200 rpm in an oil bath at 85°C for 20 hours. After removing the soybean amyloid fiber solution from the oil bath, it was immediately stored at 4°C for subsequent experiments.

[0010] Step 2: Preparation of soybean protein amyloid fiber hydrogel: Sodium alginate was dissolved in deionized water to prepare sodium alginate solutions with concentrations of 2% and 4%. The prepared soybean protein amyloid fibers were adjusted to pH 6.8 with NaOH (6 M) and mixed with sodium alginate solutions of different concentrations at a 1:1 volume ratio for half an hour. 600 mM calcium chloride was mixed with the above-prepared solutions at a 1:4 volume ratio. A 5% soybean protein sample was prepared using the same method. To obtain the best cross-linking effect, the sample was stored overnight at 4°C. Finally, it was subjected to a weight compression of 3 kPa for 5 hours.

[0011] The method for forming soybean protein amyloid fibers according to claim 1 is characterized in that the concentration of soybean protein isolate in step one is 5%, and the pH of the protein solution is adjusted to 2.0 using 6 M HCl solution.

[0012] The method for forming soybean protein amyloid fibers according to claim 1 is characterized in that the protein solution in step one is frozen and centrifuged at 10000 g for 15 min.

[0013] The method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on the pressing method according to claim 1 is characterized in that the upper protein solution is placed in a magnetically stirred oil bath at a speed of 200 rpm and a temperature of 85 ℃ in step one.

[0014] The method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression according to claim 1 is characterized in that the calcium chloride concentration in step two is 600 mM.

[0015] The method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression according to claim 1 is characterized in that the stretchable hydrogel is obtained by compression at 3 kPa for 5 h in step two.

[0016] In this invention, a pressing method is used to improve the tensile properties of the gel. This process does not contain any synthetic additives. The pressing method enhances the tensile properties of soybean protein amyloid fiber hydrogel, providing a promising approach to expanding the application of protein amyloid fibers in the food industry. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the present invention.

[0018] Figure 2 This is a cryo-scanning electron microscope image;

[0019] Figure 3 These are actual photos taken by a digital camera during the stretching process;

[0020] Figure 4 This is a tensile stress-strain diagram of the gel. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0022] A method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression, characterized by the following steps:

[0023] Step 1: Preparation of Soybean Amyloid Fiber: A soybean protein stock solution was prepared by dispersing soybean protein powder in deionized water and gently stirring for 10 hours. After centrifugation at 10000×g, a homogeneous suspension was obtained, free of fine, insoluble soybean protein solid particles. The pH was adjusted to 2.0 with HCl (6M). Under culture conditions, the solution was continuously stirred at 200 rpm in an oil bath at 85°C for 20 hours. After removing the soybean amyloid fiber solution from the oil bath, it was immediately stored at 4°C for subsequent experiments.

[0024] Step 2: Preparation of soybean protein amyloid fiber hydrogel: Sodium alginate was dissolved in deionized water to prepare sodium alginate solutions with concentrations of 2% and 4%. The prepared soybean protein amyloid fibers were adjusted to pH 6.8 with NaOH (6 M) and mixed with sodium alginate solutions of different concentrations at a 1:1 volume ratio for half an hour. 600 mM calcium chloride was mixed with the above-prepared solutions at a 1:4 volume ratio. A 5% soybean protein sample was prepared using the same method. To obtain the best cross-linking effect, the sample was stored overnight at 4°C. Finally, it was subjected to a weight compression of 3 kPa for 5 hours.

[0025] Example 1:

[0026] Sodium alginate was dissolved in deionized water to prepare a 2% sodium alginate solution. The prepared soybean protein starch-like fibers were adjusted to pH 6.8 with NaOH (6 M) and mixed with sodium alginate at a 1:1 volume ratio for half an hour. 600 mM calcium chloride was mixed with the above-prepared solution at a 1:4 volume ratio. To obtain the best cross-linking effect, the mixture was stored overnight at 4 °C. Finally, it was subjected to a weight pressure of 3 kPa for 5 h.

[0027] Example 2:

[0028] Sodium alginate was dissolved in deionized water to prepare a 4% sodium alginate solution. The prepared soybean protein starch-like fibers were adjusted to pH 6.8 with NaOH (6 M) and mixed with sodium alginate at a 1:1 volume ratio for half an hour. 600 mM calcium chloride was mixed with the above-prepared solution at a 1:4 volume ratio. To obtain the best cross-linking effect, the mixture was stored overnight at 4 °C. Finally, it was subjected to a weight pressure of 3 kPa for 5 h.

[0029] Example 3:

[0030] Sodium alginate was dissolved in deionized water to prepare a 2% sodium alginate solution. The prepared soybean protein solution was mixed with sodium alginate at a 1:1 volume ratio for half an hour. 600 mM calcium chloride was then mixed with the above-prepared solution at a 1:4 volume ratio. To obtain the best cross-linking effect, the mixture was stored overnight at 4 °C. Finally, it was subjected to a weight pressure of 3 kPa for 5 hours.

[0031] Example 4:

[0032] Sodium alginate was dissolved in deionized water to prepare a 4% sodium alginate solution. The prepared soybean protein solution was mixed with sodium alginate at a 1:1 volume ratio for half an hour. 600 mM calcium chloride was then mixed with the above-prepared solution at a 1:4 volume ratio. To obtain the best cross-linking effect, the mixture was stored overnight at 4 °C. Finally, it was subjected to a weight pressure of 3 kPa for 5 hours.

[0033] Comparative analysis of the above examples showed that the hydrogel with 2% sodium alginate exhibited better tensile properties than the hydrogel with 4% sodium alginate. The tensile properties of the four hydrogels were ranked as follows: soybean protein amyloid fiber - 2% sodium alginate - Ca... 2+ Soy protein - 2% Sodium alginate - Ca 2+ Soy protein - 4% Sodium alginate - Ca 2+ Soy protein starch-like fiber - 4% Sodium alginate - Ca 2+ .

Claims

1. A method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression, characterized in that... The method steps are as follows: Step 1: Preparation of Soybean Amyloid Fiber: A soybean protein stock solution was prepared by dispersing soybean protein powder in deionized water and gently stirring for 10 hours. After centrifugation at 10000×g, a homogeneous suspension was obtained, free of fine, insoluble soybean protein solid particles. The pH was adjusted to 2.0 with HCl (6M). Under culture conditions, the solution was continuously stirred at 200 rpm in an oil bath at 85 °C for 20 hours. After removing the soybean amyloid fiber solution from the oil bath, it was immediately stored at 4 °C for subsequent experiments. Step 2: Preparation of soybean protein amyloid fiber hydrogel: Sodium alginate was dissolved in deionized water to prepare sodium alginate solutions with concentrations of 2% and 4%. The prepared soybean protein amyloid fibers were adjusted to pH 6.8 with NaOH (6 M) and mixed with sodium alginate of different concentrations at a volume ratio of 1:1 for half an hour. 600 mM calcium chloride was mixed with the above-prepared solutions at a volume ratio of 1:

4. A 5% soybean protein group sample was prepared using the same method. To obtain the best cross-linking effect, it was stored at 4 °C overnight. Finally, it was subjected to a weight compression of 3 kPa for 5 h.

2. The method for forming soybean protein amyloid fibers according to claim 1, characterized in that... The concentration of soy protein isolate mentioned in step one is 5%, and the pH of the protein solution is adjusted to 2.0 using 6 M HCl solution.

3. The method for forming soybean protein amyloid fibers according to claim 1, characterized in that... The protein solution described in step one is centrifuged at 10,000 g for 15 min.

4. The method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression according to claim 1, characterized in that... In step one, the upper protein solution is placed in a magnetically stirred oil bath at a speed of 200 rpm and a temperature of 85 ℃.

5. The method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression according to claim 1, characterized in that... The calcium chloride concentration mentioned in step two is 600 mM.

6. The method for improving the tensile properties of soybean protein amyloid fiber hydrogel based on compression according to claim 1, characterized in that... The stretchable hydrogel is obtained by pressing at 3 kPa for 5 h as described in step two.

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