Differences and Correlations between Physicochemical Properties and Microbial Communities of Baijiu Pit Mud with Different Sensory Characteristics

This study utilized high-throughput sequencing technology combined with sensory evaluation and physicochemical analysis to investigate the differences in microbial communities, sensory attributes and physicochemical properties among pit mud with varying sensory profiles from a 6-year-old baijiu cellar. The results indicated that under the same pit age during the early maturation stage, pit mud with different sensory characteristics showed significant differences in physicochemical properties and microbial communities, which were closely related to their location and the degree of color transformation. Within the same depth range on the pit wall, the blackness of pit mud gradually increased during its maturation and was closely associated with the bacterial community. In the early maturation stage, Hydrogenispora, Sedimentibacter, Aminobacterium, and Syntrophomonas showed significant positive correlations with the pH of pit mud (P < 0.05), identifying them as key microbial groups that modify the ecological environment of pit mud and promote its aging. Low pH was found to reduce bacterial richness and diversity. Atopobium contributed to the formation of humus in pit mud. Humus in pit mud showed a significantly negative correlation with ammonium nitrogen, while other physicochemical indicators exhibited varying degrees of positive correlation. Ruminiclostridium had a significantly positive correlation with available potassium. Lactobacillus was positively correlated with Bacillus but negatively correlated with all other detected bacterial genera. This study elucidated the differences in the physicochemical and microbial properties in pit mud with different sensory profiles as well as their underlying causes, providing a theoretical basis and data support for enhancing the understanding of the aging process of pit mud and for innovating artificial pit mud cultivation and maintenance techniques.