The Influence of Seasons on the Composition of Microbial Communities and the Content of Lactic Acid during the Fermentation of Fen-Flavor Baijiu

During the fermentation of Fen-flavor Baijiu, the number of lactic acid bacteria is high in summer, resulting in excessive lactic acid and an unpleasant astringent taste. Thus, it is necessary to identify the critical influence factors for the formation of lactic acid and the composition of the microbial community in the fermented grains during the brewing process of Fen-flavor Baijiu in cold and hot seasons using HPLC and high-throughput sequencing technology. The results suggest that Lactobacillus acetotolerans is the key microorganism causing different contents of lactic acid in fermented grains and that Lactobacillus plantarum is a favorable factor for acid production in the fermentation process during hot seasons. Twelve lactic-acid-producing strains were isolated from the fermented grains at the latter stage of fermentation, and the analysis of these strains showed that the Lactobacillus plantarum LP strain has the strongest capacity for lactic acid production and the Lacticaseibacillus rhamnosus LR strain has the strongest capacity for acid production, respectively. In addition, the Lentilactobacillus hilgardii LH strain has the characteristics of both acid and alcohol resistance. The results obtained from this study provide a reference for reducing the content of lactic acid in summer and have potential value for further improving the quality of Fen-flavor Baijiu.