The Production of Intensified Qu and Its Microbial Communities and Aroma Variation during the Fermentation of Huangjiu (Chinese Rice Wine)

In recent years, intensified Qu (IQ) has been gradually applied to brewing in order to improve the aroma of Huangjiu (Chinese rice wine). In this study, Saccharomyces cerevisiae and Wickerhamomyces anomalus solutions were added to Fengmi Qu (FMQ) from Fangxian, China to produce IQ, and brewing trial was conducted. High-throughput sequencing (HTS) was used to analyze the microbial community in fermentation broth of IQ (IQFB). Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and sensory evaluation were performed to analyze volatile aroma compounds (VACs) in sample without Qu and both fermentation broths. The results showed that Pediococcus, Cronobacter, Enterococcus, Weissella, and Acinetobacter and Saccharomycopsis, Wickerhamomyces, and Saccharomyces were dominant bacterial and fungal groups, respectively. A total of 115 VACs were detected, and the content of esters including ethyl acetate, isoamyl acetate, and so on was noticeably higher in IQFB. The finding of sensory evaluation reflected that adding pure yeast to Qu could enhance fruit and floral aromas. Correlation analysis yielded 858 correlations between significant microorganisms and different VACs. In addition, prediction of microbial community functions in IQFB revealed global and overview maps and carbohydrate metabolism to be the main one. This study is advantageous for further regulation of the fermentation process of Huangjiu by microbial means.

Automated summary

In recent years, intensified Qu (IQ) has been used in the brewing of Huangjiu to enhance its aroma. This study examined the microbial community and volatile aroma compounds (VACs) in the fermentation broth of IQ. The results showed that certain bacteria and fungi were dominant in the IQFB, and the content of esters was higher compared to samples without Qu. Sensory evaluation indicated that adding pure yeast to Qu could enhance fruit and floral aromas. Correlation analysis revealed numerous associations between microorganisms and VACs. Overall, this study provides valuable insights for regulating the fermentation process of Huangjiu through microbial means.