Effect of hydrolyzed soybean on the volatile flavors and microbial community in the traditional brewing process of chi-flavor Baijiu.

Addition of soybean in raw materials could improve the flavor of chi-flavor Baijiu (CFB) in production. For investigating the mechanism of flavor improvement during fermentation, the changes of volatile flavors and their relationship with microbial community were analyzed. The results showed that the average contents of lactic and acetic acid in EG (added with hydrolyzed soybean) samples were higher those of CK (without hydrolyzed soybean) samples. The contents of main volatile esters, including ethyl acetate, ethyl palmitate, and ethyl benzoate, in EG samples were higher than those in CK samples at the end of fermentation. The content of alcohols in EG sample was 140.55 mg/L, higher than that in CK sample at the end of fermentation. Especially, the average content of characteristic flavor β-phenylethanol in EG samples increased 17.6% in comparison with that in CK samples during fermentation. Lactobacillus and Pediococcus were the dominant bacterial genera, whereas Saccharomyces, Mortierella, and Trichosporon were dominant fungal genera in both CK and EG samples. Lactobacillus and Weissella confusa showed strong positive correlation with β-phenylethanol, ethyl acetate, and ethyl benzoate. This study provides an in-depth analysis of the effects of hydrolyzed soybeans on the volatile flavor compounds and microbial communities of CFB and theoretical guidance for improving the quality of CFB.