The regulatory effects of microbial community on the formation of higher alcohols and volatile flavor components in Hongqu rice wine brewing

Abstract

The contents of higher alcohols (HAs) and volatile components produced by microbial metabolism largely determine the drinking comfort and flavor quality of Hongqu rice wine. The purpose of this study was to compare the differences of volatile flavor profile and microbial community in the brewing process of Hongqu rice wines with low and high HAs content (LHA and HHA). The results showed that the main HAs in Hongqu rice wine were isobututyl alcohol, isoamyl alcohol, phenylethyl alcohol, and the total content of HAs in HHA (749.07 ± 20.47 mg/L) was much higher than that in LHA (407.61 ± 20.80 mg/L). Multivariate statistical analysis and visualization showed that the volatile flavor characteristics of HHA and LHA were significantly different, and the contents of ethyl esters, medium- and long-chain fatty acids in HHA were higher than those in LHA. Microbiome analysis based on metagenomic sequencing indicated that fermentation starter has significant effect on the composition of microbial community during Hongqu rice wine brewing. Microbial species such as Cronobacter sakazakii, Weissella paramesenteroides, Klebsiella pneumoniae, Aspergillus niger, Millerozyma farinosa and Rhizopus delemar were significantly enriched in HHA brewing, while Pediococcus pentosaceus, Lactobacillus curvatus, Leuconostoc pseudomesenteroides and Leuconostoc mesenteroides were significantly enriched in LHA brewing. Furthermore, the potential relationships between the key microbial species and characteristic volatile components were revealed through correlation heatmap analysis. Bioinformatical analysis revealed that the abundances of microbial genes encoding enzymes involved in HAs metabolism were higher in HHA than LHA, but the gene abundance of phenylacetaldehyde dehydrogenase in LHA was significantly higher than that in HHA, which could limit the formation of HAs during Hongqu rice wine brewing. Collectively, this study provides important scientific data for enhancing the flavor quality of Hongqu rice wine, and lays a solid foundation for the healthy development of Hongqu rice wine industry.