Effect of Intensified Fermentation with Wickerhamomyces anomalus on Fungal Community Structure of Fermented Grains and Flavor Compounds of Xiaoqu Baijiu

In order to explore the effect of <i>Wickerhamomyces</i> on the production of flavor compounds in <i>Xiaoqu Baijiu</i> (<i>XQBJ</i>), this study examined the correlation between the fungal communities in <i>Xiaoqu</i> and ester compounds. It was hypothesized that <i>Wickerhamomyces</i> contributes to the aroma of Xiaoqu. Intensified fermentation methods were used to validate the role of <i>Wickerhamomyces anomalus</i> in <i>XQBJ</i> brewing. Compared to traditional <i>Xiaoqu</i>, intensified fermentation significantly increased the acidity of fermented grains and starch utilization rate (<i>p</i> < 0.05). The fungal communities in fermented grains were analyzed by high-throughput sequencing technology. The dominant fungi in both control and test groups were <i>Saccharomyces</i>, <i>Cyberlindnera</i>, <i>Rhizopus</i>, and <i>Meyerozyma</i>, with <i>Wickerhamomyces</i> replacing <i>Saccharomymycopsis</i> in the enhanced group. Flavor compounds in the fermentation experiments were analyzed, revealing that ethyl acetate content in <i>XQBJ</i> increased by 949.94 mg/L in the test group, while isoamyl alcohol decreased by 23.62 mg/L and isobutanol decreased by 34.81 mg/L. Functional prediction analysis using PICRUSt2 confirmed a higher relative abundance of enzymes involved in ethyl acetate metabolism and a lower relative abundance of enzymes involved in higher alcohol metabolism in the test group. These findings demonstrate that <i>Wickerhamomyces</i> enhances ethyl acetate production and reduces higher alcohols during <i>XQBJ</i> brewing, offering a theoretical foundation for enhancing the quality of <i>XQBJ</i>.