Preparation of soybean peptides and characteristic study of their Maillard reaction products

In this paper, the technique of using koji to produce soy sauces was simulated, soybean peptides were prepared by fermentation and enzymatic hydrolysis using high-temperature soybean meals as raw materials, and the properties of soybean peptides and their Maillard reaction products were studied. An in-depth analysis of the effects of fermentation, enzymolysis, and enzymolysis time on the antioxidant activities of soybean peptides and their Maillard reaction products was conducted through comparison of their protein recoveries, antioxidant indicators as DPPH scavenging capacities, degrees of browning and molecular weight distributions. The results showed that both fermentation and enzymolysis could significantly increase the protein recoveries and antioxidant activities of the soybean peptides prepared from soybean meals. The highest protein recovery was 77.21% after an enzymolysis time of 24 h, and the half-inhibitory concentration (IC50) of the 2,2-diphenyl-1-picryhydrazyl (DPPH)-scavenging capacity and reducing power (A700) of the enzymatic hydrolysate of soybean were 0.77 mg/mL and 0.16, respectively. However, the antioxidant activity of the Maillard reaction products could be further enhanced. Additionally, the thermal degradation of higher-molecular-weight components during the Maillard reaction was more intense, while the small molecules (oligopeptides) had higher Maillard reactivity than the large molecules. ©, 2015, South China University of Technology. All right reserved.