Physicochemical Dynamics, Microbial Succession, and Volatile Profiles of Light-Flavor Baijiu Fermented Grains Prepared from Different Rice Varieties

Light-flavor baijiu is a traditional Chinese liquor, and its flavor formation depends on the dynamic succession and metabolic regulation of the complex microbial community within the fermented grains. This study aims to elucidate the mechanisms by which different rice varieties influence the fermentation process of light-flavor baijiu fermented grains. Three representative rice varieties (glutinous rice, japonica rice and indica rice) were selected as raw materials, and the physicochemical properties, microbial community succession, and changes in flavor metabolites during 35-day fermentation were systematically monitored. The results showed that distinct dynamic patterns of physicochemical indicators including temperature, moisture, acidity, sugar content and alcohol were observed in fermented grains from different rice varieties, and differences in starch composition may be one important contributing factor for these variations. High-throughput sequencing analysis revealed that the bacterial community was dominated by Firmicutes and Proteobacteria, while Ascomycota accounted for most of the fungal community. The successional trajectories at the genus level exhibited clear raw material dependence. pH and starch content were key environmental factors associated with early-stage microbial community assembly, whereas temperature, moisture, acidity, and alcohol content were strongly related to the directional succession of the community in later stages. Flavor metabolite analysis indicated that key volatile compounds such as esters, aldehydes, and ketones accumulated in a stage-specific manner, and their changes were significantly correlated with specific functional microorganisms. This study elucidates that rice varieties influence the microecological environment, community succession patterns, and flavor-metabolite trajectories of the fermented grains, which represent flavor potential for subsequent distillation. It provides a theoretical basis for raw material selection and fermentation optimization in light-flavor baijiu production.