Microbial Diversity and Metabolites Dynamic of Light-Flavor Baijiu with Stacking Process

Abstract

Stacking is a widely used method of microbial enrichment in the field of fermentation and is traditionally used to promote flavor in Chinese sauce-flavor Baijiu; however, its precise mechanism is unknown. This study assessed the fermentation process of light-flavor Baijiu with the simplest microbial source. After comparing differences in the microbial composition of different kinds of Daqu, a high-temperature Daqu with a microbial composition that significantly differs from light-flavor Daqu was selected for stacking. The physical and chemical indicators, microbial community composition, and metabolite profiles during the fermentation process were tracked, and the total ester content in Baiju was significantly higher with stacking than Baijiu without stacking. The dominant bacteria during stacking fermentation were Bacillus and Enterococcus, while Lactobacillus was the dominant bacteria during middle and late fermentation periods. Low levels of Lactobacillus and Pichia in Daqu were screened and enriched during the stacking process, while the glucose and acetate content significantly increased. Flavor compounds such as esters and acids were positively correlated with dominant genera such as Lactobacillus, Bacillus, and Pichia. Stacking provides microorganisms for environmental screening, which regulates the microbial community structure and produces various metabolites and precursors of flavor substances to fully saccharify and promote the production of flavor substances. Stacking during the production of light-flavor Baijiu can help regulate the fermentation process and improve Baijiu quality.