The dynamics of physicochemical properties, microbial community, and flavor metabolites during the fermentation of semi-dry Hakka rice wine and traditional sweet rice wine

The dynamics of physicochemical properties, microbial community and flavor metabolites during fermentation of two typical Hakka rice wine were investigated. Results showed that total sugar content was 136.83 g/L in sweet rice wine, which almost 8 times higher than that in semi-dry rice wine. Its amino acid contents especially bitterness amino acids were also higher than those in semi-dry rice wine. Most organic acids in Hakka rice wine had the tendency of increase in initial stage of fermentation, following a decrease and finally being almost stable. A total of 131 volatiles including esters, alcohols, aldehydes, acids, ketones were detected. Pediococcus, Bacillus, Acinetobacter, Pantoea, Enterobacter and Lactobacillus were the dominant bacterial genera and Monascus, Saccharomyces, Rhizopus were the dominant fungal genera, which are strongly associated with the significant changes in flavor metabolites during Hakka rice wine fermentation. The obtained findings provided reference data for the optimization of Hakka rice wine fermentation.