Microbial community dynamics and spatial distribution of flavor compound metabolism during solid-state fermentation of Baijiu enhanced by Wickerhamomyces anomalus

Biofortification of Baijiu fermentation process using exogenous functional strains can change the microbial community structure in the fermentation system, which in turn affects the flavor of Baijiu. In this study, we used a simulated solid-state fermentation of Baijiu to investigate the effects of the addition of Wickerhamomyces anomalus strain YM001 on the improvement of Baijiu flavor compounds and its mechanism. The results of microbial diversity analysis showed that Wickerhamomyces and Lactiplantibacillus were the dominant genera in the biofortified fermentation system. In addition, W. anomalus YM001 drove the change of bacteria with moisture and alcohol content, which will synthesise esters using ethanol and moisturet as substrates. The addition of W. anomalus YM001 increased the content of total esters in fermentation samples, especially ethyl acetate, and other compounds such as acetic acid and phenylethyl ester to some extent. W. anomalus YM001 altered the correlation between microorganisms and flavor compounds, with Latilactobacillus and Pediococcus showing a significant positive correlation with ethyl acetate and Weissella showing a significant negative correlation with ethyl caproate and ethanol. In addition, the metabolic properties of ethyl acetate, ethyl decanoate and phenethyl acetate were also altered. In summary, biofortification with W. anomalus YM001 altered the microbial community composition and the physicochemical properties of the fermented grains in the Baijiu brewing system, while elevating the contents of ethyl acetate, ethyl decanoate and phenyl acetate. These findings suggest that biofortification during Baijiu brewing improves Baijiu flavor and contributes to the overall quality of Baijiu.