The dynamic of physicochemical properties, volatile compounds and microbial community during the fermentation of Chinese rice wine with diverse cereals

This study investigates the impact of liquid state fermentation on the key flavor compounds and microbial community structure in Chinese rice wine brewed from five different raw materials: buckwheat, sorghum, japonica rice, glutinous rice, and black rice. Using HS-SPME-GC-MS and HPLC, the volatile compounds were analyzed across various grain liquefaction methods, detecting 82 volatiles, including esters, alcohols, aldehydes, and acids. The concentration of flavor compounds such as esters, amino acids, phenolic acids, and organic acids varied significantly depending on the raw material used. Based on odor activity values, 31 key compounds were identified, including 15 ethyl esters, like ethyl laurate, responsible for the unique and complex aroma of the rice wines. Bitter amino acids, making up over 50% of the total amino acids, were predominant. Among the varieties, the buckwheat-fermented wine exhibited the highest ester content (27.39 mg/L), nearly double that of other samples, along with elevated amino acids (1.47 mg/mL) and phenolic acids (904.29 mg/L). Black rice ranked second in amino acid content (0.93 mg/mL), while glutinous rice had the highest organic acid content (239.76 mg/mL). Metagenomic sequencing on the fifth day of fermentation revealed significant differences in microbial community structure among the raw materials. Saccharomyces, Aspergillus, Thermomyces, Epicoccus, and Albertella were dominant fungi, while Weissella, Thermoactinomyces, Bacillus, and Saccharopolyspora were dominant bacteria. Sensory analysis showed that buckwheat-fermented rice wine was distinguished by its honey, floral, creamy, and umami attributes, while balancing alcohol, acidity, bitterness, and Qu aroma. The results demonstrate the significant influence of raw material selection and liquefaction method on both flavor profile and microbial diversity in Chinese rice wine.