Research on biologic preservatives for the preservation of fermented soy sauce

On the basis of analyzing the composi tion of Gram -positive bacterium and Gram -negative bacterium in fer-mented soy sauce,research into the i nhibitory effectiveness of Nisin on putrid bacterium which grow and surv ive in soy sauce has been undertaken.The exper iment on putrid bacterium cultivate d with different content of Nisin in n utrient -broth and soy sauce has shown the numb er of Bacillus decreases rapidly in n utrient broth at 36℃(pH4.60)with Nisin containing up 100μg per mL.The amount of Bacillus survi vors(cfu per mL )decreases to a very low level in soy sa uce with Nisin more than 50~100μg per mL.The experiment has also indi cated that Nisin can replace chemica l preservatives in sauce preservation and keeping fr esh to relieve the intensity in paste urization.