The Application Of Excellent Soy Sauce Brewing Strains

To improve the yield and quality of soy sauce by breeding excellent and safe brewing microorganisms is a scientific problem to be solved.Using global transcription factor SPT15 of Saccharomyces cerevisiae successfully complement the complementary homologous gene of Zygosaccharomyces rouxii.In our laboratory auxotrophic yeast WM was constructed,and then excellent fermentation strains WM+G(G was 0,1,2,3,4;it said YEplac195 and YEplacl95-P-T-SPT15 contains 4 kinds of SPT15 plasmid were imported WM strains)were obtained.In this study,these strains were applied to low-salt solid state fermentation,high-salt liquid state fermentation,new process I and new process II in order to obtain high quality soy sauce.First of all,through the bacterial concentration and the dilution test of these five fermentation strains temperature tolerance and salt tolerance performance were investigate.The results showed that the order of the temperature tolerance was WM+4,WM+1,WM+3,WM+2,WM+0 and the order of the salt tolerance was WM+4,WM+1,WM+2,WM+3,WM+0.Then,WM+4 and WM+1 exhibiting high temperature resistance and good salt tolerance were used in low-salt solid state fermentation and high-salt liquid state fermentation,with the control fermentation group WM+0 and WM.The physicochemical indexes such as total nitrogen determination of mash,amino nitrogen,pH value,total acid,salt and sugar was tracked and other indexes of final product such as salt free solids content,salt content,color index,organic acids and flavor substances were determined.At the same time,the economic indicators,the formation rate of amino acid and protein utilization rate were calculated.The results showed that the order of fermentation performance of four strains is WM+4>WM+1>WM+0>WM.Finally,based on the above results of the low-salt solid state fermentation and high-salt liquid state fermentation,two new process I and II with a short period were designed.A series of physicochemical indexes and economic indexes were investigated and calculated.It was found that the physicochemical indexes such as amino acid nitrogen in new process I and II were higher than those in low-salt solid-state fermented soy sauce,but slightly lower than those in high-salt liquid fermented soy sauce.But it was found that organic acids composition,volatile substances,amino nitrogen producing rate and protein utilization in new process I were higher than those in high-salt liquid fermented soy sauce.At the same time,soy sauce quality of the new process I was better than that of the new process II.Soy sauce quality of adding WM+4 fermentation group was the best,adding WM+1 fermentation group was better adding WM+0 fermentation group is poor,adding fermentation WM group was worse and without the addition of yeast fermentation group was the worst.