Application of alkaline protease in soybean peptide production

Soybeans are rich in oil and protein, of which protein accounts for about 40%. Soy protein has a large molecular weight, low solubility at low pH values, high viscosity at high concentrations, and contains anti-nutritional factors such as bloating factors, trypsin, inhibitors, and hemagglutinins. The digestibility and biological value are far less than those of animal proteins such as milk, which limits the utilization of soybean protein.

Soy peptides are a mixture of low molecular weight peptides composed of 3 to 6 amino acids obtained by enzymatic hydrolysis, chemical hydrolysis, or microbial fermentation separation and purification of soybean protein. The average molecular weight is less than 1000u and is mainly distributed between 300 and 700u. Soy peptides have functional characteristics such as high solubility, low viscosity, no precipitation under acidic conditions, good thermal stability, strong water absorption and water holding capacity, and softening food gels, which increase the added value of soybean products. As a high-quality new type of soybean deep-processing product, soybean peptides are increasingly widely used in the fields of food, medicine, and daily chemical industry, and show attractive prospects.

Soy protein isolate is a mixture with a protein content of no less than 90% obtained by removing soybean oil and water-soluble non-protein components from soybean meal. Its composition, structure and properties are similar to those of soybean protein, and it can basically represent pure soybean protein. Enzymatic preparation of small molecule soybean peptides is currently a widely adopted method, which is safe, efficient and reduces environmental protection expenses.

In the enzymatic hydrolysis of soybean protein isolate, alkaline protease, neutral protease, papain and pancreatin are usually used. The above proteins act on soybean protein isolate to prepare soybean peptides. Neutral protease and papain are used to prepare soybean peptides from soybean protein isolate. The hydrolysis is weak, the yield is low, and the taste, flavor and color are poor. The alkaline protease performs better, with strong enzymatic hydrolysis and high yield. The soybean peptide powder is light in color, and the soybean peptide aqueous solution is light in color and clear and bright. A relatively high-quality soybean peptide can be obtained, and the soybean peptide yield is high.