Microbial succession and its effect on key aroma components during light-aroma-type Xiaoqu Baijiu brewing process

Light-aroma-type Baijiu is a Chinese distilled alcoholic beverage produced from fermented sorghum. Microbial composition and dynamics during Baijiu production have a great influence on the flavor and quality of Chinese Baijiu. However, the microbial changes that occur during brewing of Xiaoqu Baijiu are poorly understood. In this study, the microbial composition of light-aroma-type Xiaoqu Baijiu at the saccharification and fermentation stages was investigated to explore microbial dynamics and their effects on aroma components using high-throughput sequencing and gas chromatography-flame ionization detection (GC-FID). Rhizopus, Pichia, Wickerhamomyces, Saccharomyces, Acinetobacter, Lactobacillus, and Weissella constituted the core microbes for Xiaoqu Baijiu production. Microbial succession during brewing could be divided into two phases: at the saccharification and early fermentation stages (F-0d to F-4d), Rhizopus and Acinetobacter were identified as the predominant microbes, accounting for 78.2-90.8% and 53.9-89.5% of the fungal and bacterial communities, respectively, whereas at the middle and late stages of fermentation (F-5d to F-14d), the abundance of Pichia, Wickerhamomyces, Saccharomyces, and Lactobacillus increased. Redundancy analysis (RDA) and Mantel tests indicated that the water, amino acid nitrogen, acid, and reducing sugar contents were significantly correlated with the fungal and bacterial communities in grains (p < 0.05). Pichia, Rhizopus, Saccharomyces, and Wickerhamomyces, especially Saccharomyces, were closely related to the contents of major alcohols, esters and aldehydes, and these microbes had an important functional role in the formation of Xiaoqu Baijiu flavor. This work provides insights into the microbial succession that occurs during brewing of light-aroma-type Xiaoqu Baijiu and the microbial contribution to flavor, which have potential for optimizing production and enhancing the flavor of Baijiu.