Study On Aspergillus Oryzae A100-8in Fermenting Soy Sauce

With the development of society and the economy, more and more people pay attention to fermented soy products. As one kind of fermented soy products, soy sauce is sought after by many people because of its unique color, fragrance, flavor and shape. Recently, the most domestic soy sauce is ferment by Aspergillus oryzae3.042. Because the market competition is more and more intense, consumers will be happy to choose the one which has better flavor. The new strain, Aspergillus oryzae A100-8constructed in our lab has high vitality enzymes. The two oryzae have been compared in the production of fluid soy sauce, but they have not been compared in the production of soy sauce so far. In this work, the two kinds of oryzae were compared in soy sauce in order to determine if Aspergillus oryzae A100-8fits to produce soy sauce and has a superiority. Then Zygosaccharomyces rouxii and Torulopsis famata were added respectively in the process of fermention to make sure if they could improve the flavor of soy sauce.By the method of response surface, the best steamed material process was determined: the rate of digestion could reach92.16%with soaking for8h, steaming temperature of120℃and steaming of25min. Through the comprehensive comparison of protease and glucoamylase activity, the best koji making craft of Aspergillus oryzae3.042was the optimal ratio of soybean:wheat of7:3, the koji making time of36h. The best koji making craft of Aspergillus oryzae A100-8was the optimal ratio of soybean:wheat of7:3, the koji making time of42h.The analysis of physical indicators in the process of fermention proved that Aspergillus oryzae A100-8was better in decomposing raw material. At the end of fermentation, the detection of organic acids showed that compared to Aspergillus oryzae3.042, the soy sauce fermente by Aspergillus oryzae A100-8contained22.1%less oxalic acid,29.7%more succinic acid and13.6%more lactate. The detection of flavor indicated that the soy sauce fermented by Aspergillus oryzae A100-8had12more kinds of esters which could contribute to the flavor of soy sauce.Then produce soy sauce by Aspergillus oryzae A100-8, Zygosaccharomyces rouxii and Torulopsis famata were added respectively in the process of fermention, with the control added no yeast. At the end of fermentation, the detection of organic acids and flavor showed that soy sauce with Zygosaccharomyces rouxii contained22.1%less oxalic than the control. Especially, it coantained45kinds of esters,6kinds more than the control. And it contained2-tiglic aldehyde and4-methoxyphenol which could contribute to the flavor of soy sauce.