The volatile profiles and microbiota structures of the wheat Qus used as traditional fermentation starters of Chinese rice wine from Shaoxing region

Abstract

Wheat Qu is used as a fermentation starter in Chinese rice wine brewing and plays important roles on the quality and flavor of the product. The aim of this study was to thoroughly investigate and compare ten traditional wheat Qus collected from different Chinese rice wine manufacturers in Shaoxing region in terms of their hydrolytic enzyme activities, volatile profiles and microbiota structures. Significant variation in the enzymatic activities (glucoamylase, amylase and protease) and volatile components were observed among the samples. Single molecule real-time DNA sequencing technology (SMRT) and culture dependent approach were combined for the first time to investigate the microbial communities in traditional wheat Qus. SMRT indicated that 4 bacterial genera, including Saccharopolyspora, Staphylococcus, Bacillus and Pantoea, and 5 fungal genera, including Aspergillus, Wickerhamomyces, Candida, Alternaria and Fusarium, dominated the wheat Qus and were detected in all ten samples. On the other hand, Staphylococcus gallinarum and Lichtheimia ramose were found to be the most abundant bacterial and fungal species by culture dependent method. Moreover, the potential correlations between microorganisms and volatiles of wheat Qus were also explored using partial least squares regression. Finally, this study provided detailed insight into the microbial communities and volatile profiles presented in wheat Qu.