Abstract:In this work, the physicochemical properties of 5 representative bacterial strains, which screened from the residue of high-salt liquid fermentation soy sauce, were analyzed to explore the growth characteristics, and to evaluate the effects of their interaction with yeast on the reproduction and flavor formation in the model system. The results showed that Bacillus amyloliquefaciens and Bacillus subtilis had stronger protease activity, while Staphylococcus saprophyticus, Kocuria kristinae and Acinetobacter johnsonii were stronger in growth activity and acid production. Among them, the salt tolerance of Bacillus amyloliquefaciens was the worst, and its colony-forming units (CFU) decreased by 98.5% compared to that without salt. In the model of interaction between bacteria and yeast, it was found that Bacillus amyloliquefaciens, Bacillus subtilis, Staphylococcus saprophyticus and Zygosaccharomyces rouxii promoted each other's growth. For example, the number of CFU of Bacillus amyloliquefaciens and yeast could increase by about 9.6 times respectively, while numbers of CFU of Staphylococcus saprophyticus and yeast could increase by about 5.2 times respectively. Meanwhile, Kocuria kristinae and its mixed culture systems had good flavor characteristics, which could improve various aroma compounds, such as acetic acid, ethyl acetate, benzene acetaldehyde, methional, 3-methylthio-1-propanol and so on, and had potential applications. This study will provide theoretical basis for the regulation of flavor in soy sauce fermentation.
