Method for improving characteristics of soybean protein isolate emulsion by using sodium alginate in cooperation with succinylation treatment

Abstract

The invention relates to a method for improving the characteristics of soybean protein isolate emulsion by using sodium alginate in cooperation with succinylation treatment, and belongs to the field of protein processing, the method comprises the following steps: (1) preparing a soybean protein isolate solution; (2) succinylation treatment of the soybean protein isolate; (3) freeze drying; (4) preparing a soybean protein isolate / succinylated soybean protein isolate-sodium alginate compound; and (5) preparing the soybean protein isolate / succinylated soybean protein isolate-sodium alginate emulsion. The modification method provided by the invention can greatly improve the emulsifying characteristic of the soybean protein isolate, and widens the application of the soybean protein isolate in the fields of food, medicine and the like.

Description

Technical Field

[0001] The present invention relates to polysaccharide modification and succinylation treatment, belonging to the field of protein processing. Background Art

[0002] Proteins are an important source of micronutrients and essential amino acids and play an important role in human health and nutrition. Legumes are regarded as the main source of protein in many countries. Soybean protein isolate (SPI) is widely used in the food industry due to its excellent nutritional value and functional properties. It is a widely sourced and effective emulsifier, generally obtained from low-temperature denatured soybean meal by the method of alkali solubilization and acid precipitation, and consists of β-conglycinin (7S) and glycinin (11S). However, SPI emulsions are very sensitive to environmental factors, with poor functional properties, showing poor stability and being not easily adaptable to processing conditions. Therefore, its commercial application is greatly restricted.

[0003] Succinylation is a very mild modification and a potential food-grade protein modification reagent. During the acylation reaction, the negatively charged succinyl group on lysine replaces the positively charged ε-amino group, increasing the electronegativity and electrostatic repulsion of the protein, promoting structural unfolding, reducing protein aggregation, and improving the solubility, emulsifying property and thermal stability of the protein. However, there are still deficiencies in the succinylation treatment of proteins. The addition of chemical substances will affect the taste of the product, and excessive addition will also pose food safety hazards.

[0004] Polysaccharides, due to their good solubility and thickening properties, are often used as stabilizers for emulsions; after their complexation with proteins, the functional properties of proteins can be improved. Sodium alginate (ALG) is an anionic polysaccharide extracted from brown algae, consisting of a linear copolymer of (1→4)-linked β-D-mannuronic acid (M) and α-L-guluronic acid (G), and has good chemical stability and thickening ability. Therefore, a more stable complex system can be formed by the electrostatic interaction, hydrophobic interaction or hydrogen bond reaction between proteins and polysaccharides.

[0005] Therefore, the degree of modification is improved through the comprehensive action of synergistic treatment to maximize the functional properties of proteins. In this study, succinylation and sodium alginate were used synergistically to modify SPI to improve the emulsion stability of SPI. This is expected to provide SPI with excellent functional properties for the food industry and broaden its application in the food industry such as dairy products, meat products, beverages and baked foods. Summary of the Invention

[0006] The present invention provides a method for improving the emulsion properties of soybean protein isolate by synergistic treatment with sodium alginate and succinylation, aiming to further improve the emulsifying properties of soybean protein isolate and broaden its application in the food industry.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for improving the emulsion properties of soy protein isolate by using sodium alginate in synergy with succinylation treatment, the method comprising the following steps:

[0009] (1) Preparation of soy protein isolate solution: Disperse soy protein isolate in deionized water to prepare a solution with a protein concentration of 20 mg / mL, place it on a magnetic stirrer for 2 h to completely dissolve it, and hydrate it overnight at 4 °C to obtain a soy protein isolate (SPI) solution;

[0010] (2) Succinylation treatment of soy protein isolate: Perform succinylation treatment on the SPI solution prepared in step (1), adjust its pH to 8.0 with 2M NaOH, and slowly add succinic anhydride (SA) to the SPI solution at a mass ratio of 20:1, 10:1, 5:1. During this process, maintain the pH value at 8.0 ± 0.2. After the solution pH stabilizes, stir for another 1 h, and dialyze the solution at 4 °C;

[0011] (3) Freeze-drying: Freeze-dry the succinylated SPI solution obtained in step (2) for 24 h to obtain succinylated soy protein isolate (SSPI);

[0012] (4) Preparation of soy protein isolate / succinylated soy protein isolate-sodium alginate complex: Disperse SPI / SSPI (4%, w / v) and sodium alginate (ALG) (0 - 1.6%, w / v) in deionized water, stir at room temperature for 2 h to completely dissolve them, and hydrate them overnight at 4 °C to obtain SPI / SSPI solution and ALG solution. Slowly add the ALG solution to the SPI / SSPI solution at a ratio of 1:1, and stir at room temperature for 2 h to fully mix them to obtain the SPI / SSPI-ALG complex;

[0013] (5) Preparation of soy protein isolate / succinylated soy protein isolate-sodium alginate emulsion: Use the SPI / SSPI-ALG complex prepared in step (4) as the aqueous phase, and corn oil as the oil phase. The volume ratio of the aqueous phase to the oil phase is 4:1. Treat it with a high-speed dispersion homogenizer (10000 r / min) for 2 min, and then homogenize it in a high-pressure homogenizer (200 - 400 Bar) for three cycles to obtain the SPI / SSPI-ALG emulsion.

[0014] In the present invention, preferably, the addition amount of SA in step (2) is 10:1;

[0015] In the present invention, preferably, the concentration of ALG in step (4) is 1.2%, w / v;

[0016] In the present invention, preferably, the average pressure of the high-pressure homogenizer in step (5) is 300 Bar.

[0017] The stability of the soy protein isolate emulsion prepared by the method of the present invention is improved. The average particle size of the soy protein isolate emulsions treated differently is reduced by 9.7 times, the emulsifying activity is increased by 2.59 times, and the emulsifying stability is increased by 1.68 times.

[0018] A more stable soy protein isolate emulsion can be obtained through the above preparation method, further expanding the application of soy protein isolate in the food industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Appendix Figure 1 Flow chart of the present method;

[0020] Appendix Figure 2 Average particle size of the soy protein isolate emulsions treated differently;

[0021] Appendix Figure 3 Emulsifying activity of the soy protein isolate emulsions treated differently;

[0022] Appendix Figure 4 Emulsifying stability of the soy protein isolate emulsions treated differently.

Claims

1. A method for improving the properties of soy protein isolate emulsion by using sodium alginate in combination with succinylation treatment, the method comprising the following steps: (1) Preparation of soy protein isolate solution: Soy protein isolate was dispersed in deionized water to prepare a solution with a protein concentration of 2%, placed on a magnetic stirrer for 2 h to completely dissolve it, and hydrated at 4 °C overnight to obtain a soy protein isolate (SPI) solution. (2) Succinylation of soy protein isolate: The SPI solution prepared in step (1) was succinylated, and its pH was adjusted to 8.0 with 2M NaOH. Succinic anhydride (SA) was slowly added to the SPI solution at a mass ratio of 20:1, 10:1, and 5:

1. During this process, the pH value was maintained at 8.0±0.

2. When the pH of the solution stabilized, it was stirred for another 1 h, and the solution was dialyzed at 4°C (3500 kDa); (3) Freeze drying: freeze drying the succinylated SPI solution obtained in step (2) for 24 h to obtain succinylated soy protein isolate (SSPI); (4) Preparation of soy protein isolate / succinylated soy protein isolate-sodium alginate complex: SPI / SSPI (4%, w / v) and sodium alginate (ALG) (0-1.6%, w / v) were dispersed in deionized water, stirred at room temperature for 2 h to completely dissolve, and hydrated at 4°C overnight. The ALG solution was slowly added to the SPI / SSPI solution at a ratio of 1:1, and stirred at room temperature for 2 h to fully mix, thereby obtaining the SPI / SSPI-ALG complex; (5) Preparation of soy protein isolate / succinylated soy protein isolate-sodium alginate emulsion: The SPI / SSPI-ALG complex prepared in step (4) was used as the aqueous phase and corn oil as the oil phase, with the volume ratio of the aqueous phase to the oil phase being 4:

1. The mixture was treated with a high-speed homogenizer (10,000 r / min) for 2 min and then homogenized three times with a high-pressure homogenizer (200-400 Bar) to obtain the SPI / SSPI-ALG emulsion.

2. The method for improving the properties of soy protein isolate-sodium alginate emulsion by succinylation treatment according to claim 1, characterized in that: The SA addition amount is 10:

1.

3. A method for improving the properties of soy protein isolate-sodium alginate emulsion by succinylation treatment according to claim 1, characterized in that: The ALG concentration was 1.2%, w / v.

4. A method for improving the properties of soy protein isolate-sodium alginate emulsion by succinylation treatment according to claim 1, characterized in that: The homogenizing pressure of the high pressure homogenizer is 300 Bar.

Images