Population dynamics and metabolite analysis of yeasts involved in a Chinese miscellaneous-flavor liquor fermentation

Baiyunbian liquor, the most popular miscellaneous-flavor liquor in China, is mainly produced in four successive fermentation batches every year. Sensory analysis based on the trained expert panel test revealed that the raw Baiyunbian liquor distilled from the last two fermentation batches always has higher quality than that distilled from the first two batches. In this study, the yeast composition, volatile compounds, and fermentation conditions associated with each fermentation batch were monitored. Significant differences were observed in the yeast community structure and fermentation parameters among different batches, which influenced the volatile profiles of the resulting liquors. Redundancy discriminate analysis and single-strain fermentation revealed that Pichia kudriavzevii and Candida humilis play important roles in enriching volatile compounds. Saccharomyces cerevisiae and Zygosaccharomyces bailii were the dominant yeasts in the last two fermentation batches. The sensorial characteristics of the liquors produced by single-strain fermentation were also analyzed. This study provides an in-depth understanding of the factors that influence liquor production and is beneficial in the development of new fermentation techniques with stable liquor quality.