The fermentation properties and microbial diversity of soy sauce fermented by germinated soybean

BACKGROUND The quality of commercial soy sauce is variable at present. Technical work is needed to improve the quality and flavor of soy sauce, especially in China. Material is a factor for influencing soy sauce characters in fermentation. RESULTS Germinated soybean sauce (fermented by germinated soybean) had a gamma aminobutyric acid (GABA) concentration of 6.83 mu g mL(-1), whereas a control (a soy sauce fermented by soybean) had a GABA concentration of less than 2.42 mu g mL(-1). Germinated soybean sauce also contained significantly higher levels of isoflavones, total polyphenol, and amino acid nitrogen than the control soy sauce. Microbial diversity results showed that Bacillus was the dominant bacteria in germinated soy sauce compared with the control. Aldehydes, alcohols, esters, and phenols were the major flavor components of germinated soybean sauce. CONCLUSION A soy sauce with high levels of GABA, isoflavones, and total polyphenol was developed using germinated soybean. Stenotrophomonas, the typical pathogen found in the control, was reduced dramatically and replaced by Bacillus during fermentation with the germinated soybean. The germinated soybean sauce exhibited a better aroma and taste than the control. Soy sauce fermented by soybeans that germinated for 48 h exhibited greater advantages than soy sauce that germinated for 24 and 72 h. (c) 2020 Society of Chemical Industry

Automated summary

Germinated soybean sauce had higher levels of GABA, isoflavones, total polyphenol, and Bacillus compared to control soy sauce fermented by normal soybeans. Germinated soybean sauce also had major flavor components of aldehydes, alcohols, esters, and phenols, exhibiting a better aroma and taste. Soy sauce fermented by soybeans germinated for 48 hours showed greater advantages than those germinated for 24 and 72 hours.