Autolysis Of Aspergillus Oryzae Mycelium And Effect On Flavuor Of Soy Sauce

Aspergillus oryzae(A.oryzae) is one of the main microorganism for soy sauce fermentation. A considerable amount of mycelium is produced in the process of koji making and autolyzes in the process of fermentation. Mycelium contains rich protein, nucleic acid, sugar and other biomacromolecules. This paper studies the autolysis law of A.oryzae and its influence on the flavor of soy sauce.In this paper, the beer A.oryzae 3.024,which is usually used brewed fungus, as experimental object. This paper studied the autolysis law of mycelium and spore of A.oryzae during the process of koji making.There were little germination of A.oryzae in the fluid of the sauce mash enzyme. The autolysis law of A.oryzae was studied in different oxygen environment, temperature(20℃、25℃、30℃、35℃、40℃),p H(4、5、6、7、8) and salt concentration(0、5%、10%、15%、20%).The result was that the temperature of 35℃, p H7,no salt,no oxygen was the most suitable autolyzed environment of the autolysis of mycelium of A.oryzae. When the mycelium of A. oryzae autolyzed 6d, the protein concentration in the solution was 223.12μg/m L, amino acid concentration was 8.80μg/m L, nucleic acid concentration was 60.05 mg/m L, reducing sugar concentration was 6.70μg/m L.In the process of soy sauce fermentation, a considerable amount of A.oryzae mycelium is produced in the process of koji making and autolyzes in the salt water in the process of fermentation. In the process of autolysis of A.oryzae mycelium, protein, amino acid, reducing sugar and nucleic acid were dissolved in large amounts. In addition, the content of organic acids and activity of a variety of enzymes all changed.In the process of autolysis(1-10d) of mycelium of A.oryzae, protein, amino acid, reducing sugar and nucleic acid are dissolved in large amounts. The maximum dissolving amounts of protein and nucleic acid account for 28.63% and 88.93% of the total, respectively, while that of reducing sugar accounts for 0.34% of the dry weight of mycelium. The content of organic acids like citric acid, tartaric acid, succinic acid, lactic acid and acetic acid increases first and then reduces with autolysis, corresponding to the change of p H.The volatile flavor compounds of mycelium of A.oryzae detected by GC-MS. And at same time, the analysis test wheather A.oryzae autolysate effects on soy sauce flavor has been made by simulating the sauce mash fermentation process.The autolyzate of mycelium of A.oryzae has rich volatile flavor compounds which are the richest at the 5dth of autolysis(52 species, total weight: 4.1521μg/g). The main characteristic flavor compounds in soy sauce as ethanol, phenylethyl alcohol and 2-methoxy-4-vinylphenol are detected 0‰, 0.4‰, 0.8‰ and 1.2‰ of mycelium were added in soy sauce koji for 60 d fermentation, respectively. The volatile compounds were 37, 51, 57 and 58 species, respectively. When 1.2‰ of A.oryzae mycelium was added, the flavor compounds were richest.