Study on the preparation of peptides from rice bran and antioxidant activity by Aspergillus oryzae fermentation

The effects of inoculum concentration, incubation time, temperature and pH on protease production and peptide content were investigated by Aspergillus oryzae fermentation.The process conditions were optimized by using response surface experiments. The molecular weights and the antioxidant activity of the peptides were analyzed.The results showed that the optimal conditions for preparation of peptides were obtained as follows:inoculum concentration of 14.6%, incubation time 48.6h, temperature 29.5℃ and pH 5.5. The content of peptides reached 128.4mg /g.The peptide molecular weights ranged from 500 to 800 u which accounted for about 75.6% of fermentation peptides.The peptides in low molecular weight had antioxidant activity.The hydroxy free radical and DPPH radical scavenging rate were 86.2% and 69.8%, respectively.