Comparison Of The Fermentation Properties On Three Aspergillus Oryzae Strains

As an indispensable condiment in people's daily diet,soy sauce plays an important role in Chinese cuisine and has a great market demand.Excellent soy sauce brewing Aspergillus oryzae can not only improve the yield of soy sauce,but also improve its quality.Therefore,by studying the difference among Aspergillus oryzae 3.042,Aspergillus oryzae TK2 and Aspergillus oryzae A,this paper provides data support for the selection of excellent strains and control of manufacturing process.The growth of Aspergillus oryzae in three strains,the Koji-making enzymes activity in the fermentation of low-salt solid and high-salt liquid soy sauce,the physicochemical indexes during fermentation,organic acids,volatile flavor substances and utilization ratio of raw materials were compared,and the main results were as follows:It was found that A.oryzae A had stronger spore producing ability according to the fact that numbers of spores of A.oryzae A after 72 h were 1.25 times of that of A.oryzae 3.042 and 1.21 times of that of A.oryzae TK2.After using the low-salt solid technology and the high-salt liquid technology to make the Koji respectively,the enzymatic activity of three strains was compared.It was found that the activities of protease,saccharifying enzyme,and cellulase of A.oryzae TK2 were higher than that of another two strains.It also showed that A.oryzae TK2 can make good use of starch and protein raw material,and can still make good use of protein raw materials even in the low pH environment of late fermentation stage.For the low-salt and solid-state fermentation soy sauce,there were more varieties of flavor compounds in the soy sauce fermented by A.oryzae 3.042,while A.oryzae TK2 was more prominent in soluble salt less solid content,nitrogen formation rate of amino acids and utilization of protein.It showed that the volatile flavor compounds of low salt solid state soy sauce fermented by A.oryzae 3.042 were optimum while the raw material utilization rate of was highest in soy sauce fermented by A.oryzae TK2.As for high-salt and anliquid-state fermentation,in the blank group,the content of oxalic acid and acetic acid of soy sauce brewed by A.oryzae TK2 was higher than that of another two strains.In addition,the results of volatile flavor compounds showed that the content of alcohols in A.oryzae TK2 was highest,and the aldehyde substance content of A.oryzae A was the highest,with the raw material utilization rate of A.oryzae A to be the best.Compared with the group with yeast,the content of organic acid in the blank group was higher,while the amount of alcohols and esters and the utilization rate of the raw materials increased in the yeast group.And A.oryzae TK2 performed best in the utilization of raw materials.Above all,brewing performance of A.oryzae TK2 and A.oryzae A was better than that of A oryzae 3.042 in the high-salt and liquid-state fermentation,and the flavor substances of soy sauce can be enriched after adding yeast.