Characterizing microbial community and metabolites of Cantonese soy sauce

Abstract The present researches aimed to investigate the difference of metabolites and the microbial community diversity among batches of Cantonese soy sauce. These results indicated that a higher abundance of lactic acid bacteria, such as Weissella, Lactobacillus originated from koji, in the initial moromi inhibited functional microbes' propagating and metabolizing, wild fungi became dominant. Therefore, the contents of dominant metabolites, including non-volatiles and volatiles as well as their species identified were significantly different. The content of dominant volatiles (Odor Activity Value, OAV >1) were 47.81%, 58.36% and 58.13%, respectively in batch 1, batch 2 and batch 3. This volatiles included ethanol, 3-methyl-1-butanol, 1-octen-3-ol, phenethyl alcohol, acetic acid, 4-ethyl guaiacol. Compared with batch 1, the contents of acetic acid and Ala increased, while that of Glu and esters decreased significantly in the samples of the other two batches. Their flavor characteristics were different from the commercial samples’ based on the Orthogonal Partial Least Squares Discrimination Analysis (OPLS-DA) and Principal Component Analysis (PCA) results due to higher content of acetic acid. Meanwhile, the strength of enzymes expression related with dominant compounds was differentiated. These results were conducive to regulating the process so that improving the quality of soy sauce.