Effects of sonication during moromi fermentation on antioxidant activities of compounds in raw soy sauce

Abstract To elucidate the effects of sonication on the antioxidant activities of compounds in soy sauce, sonication at 68 kHz (60 W/L/10 min/8 circles) was employed during moromi fermentation. Sonication enhanced four antioxidant indices of soy sauce from 5.29% to 24.29%, which were attributed to the significantly higher levels of free amino acids (FAAs, 12.45%), total phenolics (26.71%) and 1–3 kDa peptides (12.28%) in sonicated moromi. Amongst them, FAAs contributed 65.88% and 53.45% to the enhanced metal ion chelating activity and DPPH radical scavenging activity (p