ANTIOXIDANT PROPERTIES AND POSSIBLE MODE OF ACTION OF CORN PROTEIN PEPTIDES AND ZEIN PEPTIDES

Corn peptides (CPS) and zein peptides (ZPS) were prepared from defatted corn gluten meal and zein, respectively by proteolysis with alcalase, an alkaline protease. The molecular-mass distributions and amino acid compositions of CPS and ZPS were determined and compared. With a-tocopherol as the positive control, the antioxidant activities of CPS and ZPS were investigated by several in vitro assay systems, including the scavenging effects on 2, 2-diphenyl-1-picrylhydrazyl radical, the inhibiting emergence of hydroxyl radical and prevention of linoleic acidauto-oxidation and the reducing power of CPS and ZPS. The capacities of CPS and ZPS removing superoxide anion from pyrogallol auto-oxidation were also estimated. The data revealed that the antioxidant potency of CPS was similar to that of ZPS. CPS and ZPS also exhibited the similar reducing power. The possible mode of action of antioxidant activity was because of the presence of some proton-donating peptide components in CPS and ZPS products.