Abstract: With single-factor research and orthogonal test as principle, the scavenging capacity of ·OH was determined. The scavenging capacity of ·OH was highest when main parameters are found as follows: 5% rice bran, 1% yeast powder, initial pH 7.0, inoculum size 4%, medium content 25ml, temperature 27 ℃ and 140 r/min for 48 h. The scavenging capacities of ·OH. and O2· and inhibitory effects were found to highly oxidate axunge in vitro. Both supernatant fermented rice bran by Bacillus natto and water extract of rice bran have shown antioxidant activity in vitro, but the former is 0.3 fold and 10 flod higher than the same concerntration of the latter, with IC50 of ·OH and O2· 3.55 mg/ml and 23.5 mg/ml respectively. In inhibiting oxidation to axunge, the former is of higher antioxidative activities than the latter. Antioxidative activities of supernatant fermented rice bran is similar to those of VE. This is a perfect natural healthy food of higher antioxidant activity in fermented rice bran by Bacillus natto.

Key words: Bacillus natto, rice bran, hydroxyl radicals, scavenging capacity, antioxidation