Synergistic yeast co-culture system for improved ethyl hexanoate production in Chinese baijiu fermentation

This study aimed to enhance ethyl hexanoate production in strong-flavor baijiu by developing a synergistic yeast co-culture system and investigating the underlying metabolic basis for flavor improvement.

Wickerhamomyces anomalus CHXQ, a strain with relatively high ethyl hexanoate-producing capacity, was isolated from Daqu and co-cultured with Saccharomyces cerevisiae CH1-a. After optimization, ethyl hexanoate yield in the optimized co-culture liquid fermentation reached 10.03 mg L-1, 2.33 times higher than W. anomalus monoculture (4.31 mg L-1). Transcriptomic analysis revealed upregulation of EEB1 and FAA2 in S. cerevisiae, suggesting enhanced precursor supply and intracellular esterification. In simulated solid-state fermentation, the co-culture system significantly increased alcohol (40.77% vol) and total ester content (0.80 g L-1), with ethyl hexanoate rising to 1103.63 mg L-1, representing a 1.53-fold increase over the control group.

The co-culture system promotes ethyl hexanoate synthesis through metabolic interaction and transcriptional regulation, resulting in an enhanced ester profile conducive to improved baijiu flavor quality and fermentation performance.