Daqu is a traditional starter for Baijiu fermentation and is produced by spontaneous fermentation of ground and moistened barley or wheat. The quality of Daqu is traditionally evaluated based on physicochemical and subjective sensory parameters without microbiological analysis. Here, we compared the physicochemical characteristics of qualified (QD) and inferior (ID) Daqu, their microbial communities based on plate counting and PacBio SMRT sequencing of rRNA gene libraries, and their impacts on Baijiu fermentation. The results showed that the glucoamylase and α-amylase activities of QD were significantly higher than those of ID. The counts of yeasts and relative abundances of functional microbes, especially the amylolytic bacterium Bacillus licheniformis and fungi Saccharomycopsis fibuligera and Lichtheimia ramosa, were significantly higher in QD than in ID. The laboratory-scale Baijiu fermentation tests showed that the relative abundances of the amylolytic microbes were higher in the QD than the ID fermentation set, resulting in more efficient fermentation, as indicated by more weight loss and higher moisture content in the former. Consequently, more glycerol, acetic acid, ethanol, and other volatile compounds were produced in the QD than in the ID fermentation set. The results suggest that Daqu quality is determined by, and can be evaluated based on, its microbial community.

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.

Chinese Baijiu is a famous fermented alcoholic beverage in China. Interactions between key microorganisms, i.e., Saccharomyces cerevisiae and Lactiplantibacillus plantarum, have recently been reported at specific temperatures. However, empirical evidence of their interactions at various temperatures during fermentation is lacking. The results of this study demonstrated that S. cerevisiae significantly suppressed the viability and lactic acid yield of L. plantarum when they were cocultured above 15 °C. On the other hand, L. plantarum had no pronounced effect on the growth and ethanol yield of S. cerevisiae in coculture systems. S. cerevisiae was the main reducing sugar consumer. Inhibition of lactic acid production was also observed when elevated cell density of L. plantarum was introduced into the coculture system. A proteomic analysis indicated that the enzymes involved in glycolysis, lactate dehydrogenase, and proteins related to phosphoribosyl diphosphate, ribosome, and aminoacyl-tRNA biosynthesis in L. plantarum were less abundant in the coculture system. Collectively, our data demonstrated the antagonistic effect of S. cerevisiae on L. plantarum and provided insights for effective process management in light-flavor Baijiu fermentation.

Four yeast strains belonging to the ascomycetous yeast genus Ascoidea were isolated from the mixture of remnants of steamed sorghum, Daqu powder and the fermented grain that fell off during transportation on the ground in the workshop which were collected in Xinghuacun Fenjiu old workshop, Shanxi province, PR China. We propose the name Ascoidea xinghuacunensis sp. nov. (holotype: strain CGMCC 2.7787) for the new species, which differs phenotypically from the other three species in this genus: Ascoidea asiatica, Ascoidea rubescens and Ascoidea tarda by its ability to grow at 37 °C. This study represents the first isolation of Ascoidea species within the borders of China and the initial report of the Ascoidea species detailing the isolation from the Baijiu brewing environment.

The aging population highlights the urgency of interventions targeting oxidative stress and neuroinflammation. This study investigated the anti-aging potential of Zhuyeqing Liquor Extract (ZLE) using hydrogen peroxide (H₂O₂)-induced HT-22 cells and D-galactose-induced aging mice model. Results demonstrated that ZLE exhibited free radical scavenging activity, mitigated neuronal oxidative damage, and suppressed pro-inflammatory cytokine expression. Meanwhile, ZLE alleviated age-related physiological deterioration, improved spatial learning and memory ability, and protected hippocampal neurons in aging mice. Mechanistic analysis revealed that ZLE exerted the bioactivity by activating the SIRT1-Nrf2-HO-1 antioxidant pathway while inhibiting the NF-κB inflammatory pathway. This study suggested that ZLE may have potential as a neuroprotective functional food ingredient, providing a scientific basis for its further development.