Optimization of Immobilization Conditions for Protease and Its Application in the Fermentation of Soy Sauce

The aim of this research was to increase the protein conversion ratio and short the fermentation period of traditional Chinese soy sauce by using immobilization technics.The concentration of sodium alginate,calcium chloride,volume ratio of enzyme to carrier solution and immobilization time were selected as the factors to optimize the immobilization process of neutral protease powder,and the immobilized neutral protease powder was applied in the fermentation of high-salt liquid state soy sauce.The results indicated that the optimal immobilization process condition of immobilized gel particles with good stability and the highest relative enzyme activity were 0.007 M sodium alginate,0.27 M calcium chloride,and the volume ratio of enzyme to carrier solution 12:30 after immobilizing for 2 hours.Contrast to the control group,the index contents of the dissociative and immobilized group added with 5.80 g neutral protease in 17.5 kg sauce mash were improved significantly during the fermentation process,and the fermentation period was shorten by about 20 days;and the protein conversion rate of the immobilized protease powder group was improved by about 6.08% and 1.88% respectively,compared to the control and dissociative enzyme group.It is concluded that the immobilized neutral protease powder could improve the protein conversion rate and shorten the fermentation period of the fermentation of high-salt liquid state soy sauce.