A study on anti-oxidative activity of soybean peptides with linoleic acid peroxidation systems

Soybean bioactive peptides (SBPs) were prepared from the isolated soybean protein by proteolysis with an alkaline protease, alcalase, at 50 degrees C and pH = 8.0. The dependence of hydrolysis time on hydrolysis degree and molecular weight distribution were examined. The hydrolysate was fractionated on a Sephadex G-25 column and the anti-oxidative activities of the fractions were detected by the method of pyrogallol auto-oxidation. The average chain length of soybean peptides that have anti-oxidative activity was estimated to be about 7. The anti-oxidative properties of the soybean peptide were also studied by using linoleic acid peroxidation systems. The optimal condition of the peroxidation system was set up, Vc/Cu2+ as the inducer at pH = 7. 4 and 25 degrees C. In addition, soybean peptides show higher antioxidative activity compared with GSH.