Analysis of Differences in Microbial Community, Sensory and Physicochemical Properties of Different Layers of Alcoholic Fermentative Material in Maotai-flavor Baijiu Cellar in the Fifth Round of Fermentation

In this study, multi-dimensional characterization of different layers of alcoholic fermentative material in Maotai-flavor baijiu cellar in the fifth round of fermentation from a certain region in Hubei was carried out by route analysis, culturable methods, metagenomics, and bionic methods. The results showed that there was no significant difference in the counts of total bacteria, lactic acid bacteria, or yeast and mold among different layers of alcoholic fermentative material (P > 0.05). However, acidity, alcohol content, starch content and reducing sugar content were significantly higher in the middle than lower layer (P < 0.05). Sensory evaluation showed that the lower layer had a stronger bitter taste and bitter aftertaste as well as higher concentrations of nitrogen oxides and methane. The analysis of sequencing data from the MG-RAST database for the fourth round of fermentation showed that the major genera in alcoholic fermentative material were Acetilactobacillus and Sarocladium, whose relative abundance in alcoholic fermentative material was significantly different between the fourth and fifth rounds of fermentation (P < 0.05). Also, there was a significant difference in the microbial community structure of alcoholic fermentative material between the two rounds (P < 0.05), while the difference in the microbial community structure among different layers of alcoholic fermentative material was relatively small. Correlation analysis showed that there was a close relationship between microorganisms in alcoholic fermentative material and its sensory and physicochemical quality.