Antioxidant Properties And Synergistic Effect Of Soybean Peptides

Being an important functional plant protein resources, antioxidant activity of soy peptide has widely attracted much attention in recent years. Although separation and purification of soy peptide had been studied widely at present, interaction of soy peptides with other antioxidant components rarely has been reported. Thus, in this work, we research ultrafiltration method to get soy peptide from the point of industrial applications. In addition, antioxidant activity of soy peptide and antioxidant synergy of it respectively with VC, VE, TP are also researched, which will build the foundation for industrial production and broadening its applications.Firstly, enzymatic hydrolysis process of soybean protein were studied with alkaline protease enzymolysis method. The degree of hydrolysis and reducing power are selected as comprehensive survey indicators, and then the optimum conditions are got by using response surface methodology: substrate concentration 4.73%, enzyme dosage 4.33%, pH 8.35, reaction temperature 59 ?. Under this condition, the degree of hydrolysis of soy protein isolate was 22.10% ± 0.15%, and reducing power was 0.498 ± 0.024.Secondly, soy peptide was separated with ultrafiltration method which has the application in industry. In addition, the antioxidant activity were investigated in these systems of DPPH·, ·OH, superoxide anion radical and reducing power. The results showed that: operating pressure 0.2 MPa; concentration 50 g /L; operating time 80 min for 10 KD, 3 KD and 1 KD; ultrafiltration membrane, 100 min for 5 KD membrane membrane. Under this condition, the ultrafiltration membrane flux was higher, and the result of ultrafiltration was better. Every fraction of soybean peptide has certain degree of antioxidant activity after ultrafiltration, and the antioxidant activity of soybean peptide gradually increased with decreasing of molecular weight cutoff of ultrafiltration. Besides, soybean peptide had higher oxidation activity when the molecular weight lower than 3 KD.Finally, antioxidant synergy between soybean peptides and VC, VE, TP were comprehensively studied by measuring DPPH·clearance, ·OH clearance, superoxide anion clearance and reducing power, and then collaborative coefficient is taken as the indicator to analyze interaction between these synergistic antioxidants. Besides, the reason of interaction was analyzed preliminarily.