Antioxidant and free radical scavenging activity of methanol extract of chungkukjang

An assessment of chungkukjang (traditional fermented soyfood) fermented at 42 °C for 72 h with six sample groups of Korean black soybean (Glycine max) was carried out. Total phenol and isoflavone contents of large black soybean (LBS) group extracts were higher than that of small black soybean (SBS) group extracts. Genistein contents were higher than daidzein in all groups. In total anthocyanin pigment, LBS groups were similar to SBS groups. LBS group extracts exhibited good inhibition rate of about 70–90% in antioxidant and some scavenging activities of free radicals as well as hydrogen peroxide. Bacillus megaterium SMY-212 was a suitable fermenting strain to promote the antioxidant and free-radical scavenging activities in cooked black soybean.