Method for improving functional characteristics of glycinin by using astragalus polysaccharide

Abstract

The invention discloses a method for improving functional characteristics of glycinin by utilizing astragalus polysaccharide, and belongs to the technical field of protein modification. The method comprises the following steps: (1) preparing glycinin (11S); (2) preparing a glycinin-astragalus polysaccharide compound (SAs); and (3) freeze-drying to obtain the SAs compound. According to the modification method, the foamability of the glycinin can be improved (foaming activity is 1.68 times; the foam stability is 1.36 times) and the emulsibility is 1.78 times (the emulsifying activity is 1.78 times); the soybean protein-polysaccharide has the functional characteristics of high-value soybean protein-polysaccharide, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein, high-value soybean protein

Description

Technical Field

[0001] The invention mainly relates to a method for improving the functional properties of soybean globulin by utilizing astragalus polysaccharide, and belongs to the technical field of protein modification. Background Art

[0002] Soybean globulin (11S) is one of the main components of soybean protein, with a molecular weight of about 300-360 kDa, accounting for about 52% of the total soybean protein. 11S is composed of five main types of subunits, and the acidic and basic polypeptide chains are connected by hydrophobic interactions and disulfide bonds to form a hexamer. This complex structure gives it high molecular stability, but its tight molecular structure limits the molecular flexibility and functional properties. In food production, it shows weak emulsification and foaming properties, and has low solubility, which makes it difficult to meet the diversified needs in food processing. Therefore, modifying soybean globulin to make it have better solubility, emulsification and other functional properties is a necessary way to expand its application in the food industry.

[0003] Astragalus is a leguminous plant widely cultivated in China. The rhizome of Astragalus is commonly consumed as a functional food and traditional medicine for its various nutritional benefits and bioactivities. The bioactive components in Astragalus are very complex and contain polysaccharides, flavonoids, and astragaloside IV. Astragalus polysaccharide (APS) is the main active ingredient of the Astragalus herb, mainly composed of rhamnogalacturonan II pectin and α-(1→4) glucan. APS has a variety of reported health benefits and has the properties of an immunomodulator, antioxidant, anticancer agent, anti-aging agent, antiviral agent, and antibacterial agent. APS has excellent biocompatibility, stability, and functional activity. The complexation of polysaccharides with proteins can improve the functional properties of proteins, and the functional groups on the polysaccharide backbone can be coupled with the functional groups in proteins to form new polymers. APS interacts with proteins through covalent and noncovalent bonds, and the covalent bonds produce aggregates, which can promote the generation of active substances. The solubility and emulsification of proteins can be improved by the hydrophilicity and steric hindrance of APS.

[0004] However, in current research, the effect of astragalus polysaccharide on the functional properties of soybean globulin is not clear. The present invention prepares the astragalus polysaccharide and soybean globulin complex by changing the stirring temperature, and optimizes the mixing ratio of astragalus polysaccharide and soybean globulin to improve the functional properties of soybean globulin such as foaming. This not only provides technical support for the extensive development and application of soybean globulin in the food industry, but also helps to promote the design and development of protein-polysaccharide foods with high functional and nutritional properties. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a method for improving the functional properties of soybean globulin by using astragalus polysaccharide.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A method for improving the functional properties of soybean globulin by using astragalus polysaccharide, the method comprising the following steps:

[0008] (1) Preparation of soybean globulin (11S): Deionized water and defatted soybean meal were uniformly mixed at a ratio of 1:15 (w / v), and the pH was adjusted to 7.5. After complete dissolution, the sample was centrifuged at 4°C and 9,000 g for 30 min, the supernatant was collected, and NaHSO3 (0.01 mol / L) was added; the pH was then adjusted to 6.4, and the sample was refrigerated at 4°C for 12 h; the sample was then centrifuged at 4°C and 6,500 g for 20 min, and washed with deionized water several times in small amounts to precipitate 11S, which was redispersed in deionized water, the pH was adjusted to 7.0, and finally freeze-dried in a vacuum freeze dryer at -45°C for 48 h.

[0009] (2) Preparation of soybean globulin-astragalus polysaccharide complex (SAs): 11S was uniformly dispersed in deionized water (2%, w / v), and different concentrations (0.05%, 0.1%, 0.15% and 0.2%, w / v) of astragalus polysaccharide (APS) were added, while stirring continuously at 300 rpm at 25°C, 35°C and 45°C; after adding APS, the pH of the solution was adjusted to 7.0, and the solution was stirred at 600 rpm for 2 h; finally, the solution was treated with an ultrasonic cell disruptor at 180 W for 30 min to obtain a SAs dispersion.

[0010] (3) Freeze-drying to obtain SAs complex: The SAs dispersion was freeze-dried in a vacuum freeze dryer at -45°C for 48 h to obtain the SAs complex. The SAs complexes prepared by different concentrations of APS (0.05%, 0.1%, 0.15% and 0.2%, w / v) and 11S were named SAs-1, SAs-2, SAs-3 and SAs-4, respectively. The heat-treated 11S was named 11SH.

[0011] The preferred condition is that the APS concentration is 0.15% (w / v);

[0012] The preferred condition is that the stirring temperature is 35°C.

[0013] The invention improves the functional properties of soybean globulin to a certain extent. Astragalus polysaccharide modification increases the foaming activity of soybean globulin by 1.68 times, the foam stability by 1.36 times, the emulsifying activity by 1.78 times, the emulsifying stability by 1.45 times and the solubility by 1.65 times.

[0014] The soybean globulin obtained by the above preparation method has excellent functional properties, which provides technical support for the wide application and development of soybean globulin in food processing, and also helps to promote the design and development of protein-polysaccharide foods with valuable functions and nutritional properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Attached Figure 1 The technical roadmap of this method (preparation of astragalus polysaccharide and soybean globulin complex);

[0016] Attached Figure 2 Foaming activity and foam stability of soybean globulin modified with different concentrations of astragalus polysaccharide;

[0017] Attached Figure 3 Emulsifying activity and emulsifying stability of soybean globulin modified with different concentrations of astragalus polysaccharide;

[0018] Attached Figure 4 Solubility of soybean globulin modified with different concentrations of astragalus polysaccharide; DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0020] A method for improving the functional properties of soybean globulin by using astragalus polysaccharide, the method comprising the following steps:

[0021] (1) Preparation of soybean globulin (11S): Deionized water and defatted soybean meal were uniformly mixed at a ratio of 1:15 (w / v), and the pH was adjusted to 7.5. After complete dissolution, the sample was centrifuged at 4°C and 9,000 g for 30 min, the supernatant was collected, and NaHSO3 (0.01 mol / L) was added; the pH was then adjusted to 6.4, and the sample was refrigerated at 4°C for 12 h; the sample was then centrifuged at 4°C and 6,500 g for 20 min, and washed with deionized water several times in small amounts to precipitate 11S, which was redispersed in deionized water, the pH was adjusted to 7.0, and finally freeze-dried in a vacuum freeze dryer at -45°C for 48 h. (2) Preparation of soybean globulin-astragalus polysaccharide complex (SAs): 11S was uniformly dispersed in deionized water (2%, w / v), and different concentrations (0.05%, 0.1%, 0.15% and 0.2%, w / v) of astragalus polysaccharide (APS) were added, and stirred continuously at 300 rpm at 25°C, 35°C and 45°C; after adding APS, the pH of the solution was adjusted to 7.0, and the solution was stirred at 600 rpm for 2 h; finally, the solution was treated with an ultrasonic cell disruptor at 180 W for 30 min to obtain a SAs dispersion. (3) Freeze drying to obtain a SAs complex: The SAs dispersion was freeze-dried in a vacuum freeze dryer at -45°C for 48 h to obtain a SAs complex.

[0022] Implementation Case 1

[0023] Deionized water and defatted soybean meal were uniformly mixed at a ratio of 1:15 (w / v), and the pH was adjusted to 7.5. After complete dissolution, the sample was centrifuged at 4°C and 9,000g for 30min, the supernatant was collected, and NaHSO3 (0.01mol / L) was added; then the pH was adjusted to 6.4 and refrigerated at 4°C for 12h; then centrifuged at 4°C and 6,500g for 20min, washed with deionized water in small amounts for multiple times, precipitated as 11S, which was redispersed in deionized water, the pH was adjusted to 7.0, and finally freeze-dried at -45°C for 48h using a vacuum freeze dryer. 11S was uniformly dispersed in deionized water (2%, w / v), 0.1% astragalus polysaccharide (APS) was added, and it was continuously stirred at 300rpm at 45°C; after adding APS, the solution pH was adjusted to 7.0, and the solution was stirred at 600rpm for 2h; finally, the solution was treated with an ultrasonic cell disruptor at 180W for 30min to obtain a SAs dispersion. SAs dispersion was freeze-dried in a vacuum freeze dryer at -45℃ for 48h to obtain SAs complex. Astragalus polysaccharide modification increased soybean globulin foaming activity by 1.39 times, foam stability by 1.2 times, emulsification activity by 1.46 times, emulsification stability by 1.31 times, and solubility by 1.44 times.

[0024] Implementation Case 2

[0025] Deionized water and defatted soybean meal were uniformly mixed at a ratio of 1:15 (w / v), and the pH was adjusted to 7.5. After complete dissolution, the sample was centrifuged at 4°C and 9,000g for 30 min, the supernatant was collected, and NaHSO3 (0.01 mol / L) was added; then the pH was adjusted to 6.4 and refrigerated at 4°C for 12 h; then centrifuged at 4°C and 6,500g for 20 min, washed with deionized water in small amounts several times, precipitated as 11S, redispersed it in deionized water, adjusted the pH to 7.0, and finally freeze-dried in a vacuum freeze dryer at -45°C for 48 h. 11S was uniformly dispersed in deionized water (2%, w / v), and 0.15% astragalus polysaccharide (APS) was added, while stirring continuously at 300 rpm at 35°C; after adding APS, the pH of the solution was adjusted to 7.0, and the solution was stirred at 600 rpm for 2 hours; finally, the solution was treated with an ultrasonic cell disruptor at 180W for 30 minutes to obtain a SAs dispersion. The SAs dispersion was freeze-dried in a vacuum freeze dryer at -45°C for 48 hours to obtain a SAs complex. Astragalus polysaccharide modification increased the foaming activity of soybean globulin by 1.68 times; the foam stability by 1.36 times; the emulsification activity by 1.78 times; the emulsification stability by 1.45 times; and the solubility by 1.65 times.

[0026] Implementation Case 3

[0027] Deionized water and defatted soybean meal were mixed evenly at a ratio of 1:15 (w / v), and the pH was adjusted to 7.5. After the sample was completely dissolved, Centrifuge at 4°C and 9,000g for 30min, collect the supernatant, add NaHSO3 (0.01mol / L); then adjust the pH to 6.4 and refrigerate at 4°C for 12h; then centrifuge at 4°C and 6,500g for 20min, wash with deionized water in small amounts several times, precipitate 11S, redisperse it in deionized water, adjust the pH to 7.0, and finally freeze-dry it at -45°C for 48h in a vacuum freeze dryer. 11S was evenly dispersed in deionized water (2%, w / v), and 0.2% astragalus polysaccharide (APS) was added, while stirring continuously at 300rpm at 25°C; after adding APS, the pH of the solution was adjusted to 7.0, and the solution was stirred at 600rpm for 2h; finally, the solution was treated with an ultrasonic cell disruptor at 180W for 30min to obtain a SAs dispersion. The SAs dispersion was freeze-dried at -45°C in a vacuum freeze dryer for 48h to obtain a SAs complex. Astragalus polysaccharide modification increased the foaming activity of soybean globulin by 1.26 times, the foam stability by 1.15 times, the emulsifying activity by 1.53 times, the emulsifying stability by 1.23 times, and the solubility by 1.22 times.

Claims

1. A method for improving the functional properties of soybean globulin using astragalus polysaccharide, the method comprising the following steps: (1) Preparation of soybean globulin (11S): deionized water and defatted soybean meal were uniformly mixed at a ratio of 1:15 (w / v), and the pH was adjusted to 7.

5. After complete dissolution, the sample was centrifuged at 4°C and 9,000 g for 30 min, the supernatant was collected, and NaHSO3 (0.01 mol / L) was added; the pH was then adjusted to 6.4, and the sample was refrigerated at 4°C for 12 h; the sample was then centrifuged at 4°C and 6,500 g for 20 min, and washed with deionized water several times in small amounts to precipitate 11S, which was redispersed in deionized water, the pH was adjusted to 7.0, and finally freeze-dried in a vacuum freeze dryer at -45°C for 48 h; (2) Preparation of soybean globulin-astragalus polysaccharide complex (SAs): 11S was uniformly dispersed in deionized water (2%, w / v), and different concentrations (0.05%, 0.1%, 0.15% and 0.2%, w / v) of astragalus polysaccharide (APS) were added, while stirring continuously at 300 rpm at 25°C, 35°C and 45°C; after adding APS, the pH of the solution was adjusted to 7.0, and the solution was stirred at 600 rpm for 2 h; finally, the solution was treated with an ultrasonic cell disruptor at 180 W for 30 min to obtain a SAs dispersion. (3) Freeze-drying to obtain SAs complex: The SAs dispersion was freeze-dried in a vacuum freeze dryer at -45°C for 48 h to obtain the SAs complex. The SAs complexes prepared by different concentrations of APS (0.05%, 0.1%, 0.15% and 0.2%, w / v) and 11S were named SAs-1, SAs-2, SAs-3 and SAs-4, respectively. The heat-treated 11S was named 11SH.

2. The method for improving the functional properties of soybean globulin by using astragalus polysaccharide according to claim 1, characterized in that: The ASP concentration was 1.5% (w / v).

3. The method for improving the functional properties of soybean globulin by using astragalus polysaccharide according to claim 1, characterized in that: The heating and stirring temperature was 35°C.

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