Effect of co-inoculation of different halophilic bacteria and yeast on the flavor of fermented soy sauce

The flavor of soy sauce is closely related to the succession and interaction of the microbial community during fermentation. In this study, the selected potential flavor-producing microorganisms (7 species of bacteria and 4 species of yeast) were applied in the co-culture rapid fermentation model and their growth, physicochemical changes, volatile flavor compounds (VFCs), and sensory characteristics were investigated. Results showed that yeast promoted the growth of bacteria, while bacteria inhibited the growth of yeast in the co-culture model. Based on the results of VFCs and sensory evaluation, the combined fermentation of Zygosaccharomyces rouxii and Lactobacillus fermentum was the best strategy out of the 40 combinations. The effect of this combination was also validated in a 20 L fermentation application of soy sauce, which indeed enhanced the intensity of sauce-like, fruity, smoky, and caramel-like notes, as well as umami and kokumi tastes. These results provide a theoretical basis for the exploration and industrial application of flavor-producing microorganisms in soy sauce fermentation.