Optimization of the enzymatic hydrolysis condition to improve the degree of hydrolysis of mixed fermentation of tilapia scraps and soybean meal with response surface methodology

With tilapia and soybean meal as raw material, neutral protease was added before the fermentation of mixed bacteria including bacillus subtilis, yeast and lactic acid. On the basis of single- factor experiment, the optimize process conditions of mixed fermentation was studied by response surface optimization method, taking degree of hydrolysis as response value, the optimized process conditions were: neutral protease addition 0.1%, fermentation temperature 40℃, fermentation time 53h.Under these conditions, the degree of hydrolysis was 31.94%, which was 4.7% higher than the ones fermented by pure bacteria.