Characteristics of four yeasts and the effects of yeast diversity on the fermentation of baijiu

The fermentation process of Chinese baijiu involves complex microbiota. As the main category of microorganisms in the fermentation process, yeasts in different species have been screened, but their interactions remain unclear. In this study, fermentation characteristics, including ethanol and enzyme production capacity, growth capacity, sensory evaluation and characteristic flavor compounds, of four different species and their interactions with Aspergillus oryzae in sorghum were evaluated. Then, the effect of increased yeast diversity on the fermentation results was analyzed. Saccharomycopsis fibuligera exhibited the best fermentation function, with outstanding alcohol and enzyme production ability. Moreover, S. fibuligera could synthesize unique volatile aroma compounds such as isobutanol, ethyl laurate and benzaldehyde. Principal component analysis showed that the addition of A. oryzae had a significant effect on the fermentation results. With an increase in the diversity of yeasts, the concentrations of ethyl phenylacetate and ethyl decanoate increased by 22.3 and 119.6 times, respectively. However, when the four yeasts were added to the fermentation system, the sensory results showed a rancidity taste. This study revealed the influences of yeast fermentation characteristics and yeast diversity on the quality of fermented products during fermentation, thus providing insight into the fermentation mechanism of Chinese baijiu.