Reducing, Radical Scavenging, and Chelation Properties of Fermented Soy Protein Meal Hydrolysate by Lactobacillus plantarum LP6

Fermented soybean protein meal hydrolysate (FSPMH) was fractionated by gel filtration on Sephadex G-15. The fractions obtained were subjected to various antioxidant assays, amino acid and molecular weight determinations. Among the seven fractions, the highest antioxidant activity was found in fraction F2, with significant differences (P 0.01) 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, hydroxyl radicals (.OH) scavenging and Cu2+ chelating activity. Fraction F2 exhibited scavenging of DPPH (59.43%), .OH (72.80%) and 44.47% Cu2+ chelating activity. All other fractions showed variable activities in different assays. Amino acid analyses of F2 fraction with the strongest antioxidant activity also had the highest percentage of related antioxidative amino acids content (Histidine 3.46, Serine 5.78, Valine 4.08 and Lysine 11.49 g/100 g protein) compared with other six fractions. The molecular weight distribution of F2 was found to vary from 170 to 1500 Da.