The quality of fermented product is closely related to the enzyme production capacity and fermentation conditions of the microorganisms.In order to improve the fermentation quality of fermented soya beans,the single factor method combined with the response surface method is used to optimize the fermentation conditions of fermented soya beans by a strain of Bacillus velezensis with high production of fibrinolytic enzyme.After single factor experiment,the ranges of fermentation temperature,time and inoculation amount are reduced.And then,the optimum fermentation conditions are determined by response surface method with amino acid nitrogen and fibrinolytic enzyme activity of fermented soya beans as the indicators,that is the time of 5 d,the temperature of 35℃and the inoculation amount of 0.01%.Finally,the amino acid nitrogen content is 8.95 g/kg,the fibrinolytic activity is420.05 IU/g.Compared with the commercial products,the fibrinolytic activity of fermented soya beans is increased by about 400 times.This study has provided a theoretical basis for the fermentation of fermented soya beans by Bacillus velezensis.
response surface methodology
fermented soya beans
amino acid nitrogen
fibrinolytic enzyme of fermented soya beans