Optimization of Solid-state Fermentation of Peanut Meal by Mixed Bacteria

The peanut meal was fermented in a solid state by a mixture of Bacillus natto and Monascus. The activity of nattokinase and the content of γ-aminobutyric acid were used as indicators. Through single factor experiment and orthogonal experiment,the fermentation temperature,time,feed-water ratio,strain proportion and inoculation amount were optimized. The optimum process parameters were determined as follows:Temperature 31 ℃,fermentation time 46 h,the ratio of material to water was 1:0.4 g/mL,the proportion of strains(Bacillus natto:Monascus)2:1,inoculation 6%. Under these conditions,the activity of nattokinase was(844.56±13.80) U/g,the content of γ-aminobutyric acid was(105.25±0.25) mg/g,The hydroxyl radical scavenging rate was 68.46%±0.16%,the DPPH· clearance rate was 76.98%±0.95%,and the OD value of iron reducing power was 0.481.