Study on relationship between bacterial diversity and quality of Huangjiu (Chinese Rice Wine) fermentation

Abstract

Huangjiu (Chinese rice wine) is brewed in an open environment, where bacteria play an important role during the fermentation process. In this study, bacterial community structure and composition changes in the fermented mash liquid of mechanized Huangjiu, well‐fermented manual Huangjiu (wines of good qualities), and poorly fermented manual Huangjiu (wines of poor qualities: spoilage, high acidity, low alcohol content) in different fermentation stages from Guyuelongshan Shaoxing Huangjiu company were analyzed via metagenomic sequencing. And bacterial metabolic difference was analyzed via gene prediction of metabolic pathway enzymes. The results showed that the bacterial diversity degree was abundant, and the number of bacterial species in every sample was approximately 200–400. Lactic acid bacteria (LAB) dominated the bacterial community of Huangjiu fermentation, and lactobacillus was predominant species in well‐fermented Huangjiu while Lactobacillus brevis had an absolute dominance in spoilage Huangjiu. Further, gene prediction revealed that transformation of malate to pyruvate and lactate anabolism was more active in mash liquid of well‐fermented manual Huangjiu, while acetate accumulation was stronger in mash liquid of poorly fermented manual Huangjiu, which explained acidity excess reason in poorly fermented Huangjiu at gene level.

Metabolites comparison in post-fermentation stage of manual (mechanized) Chinese Huangjiu (yellow rice wine) based on GC–MS metabolomics

“…The species and abundance of microorganisms in different fermented mash were significantly different due to the different types and dosage of wheat Qu . The preliminary study of our laboratory found that there were more bacterial species in well-fermented manual Huangjiu, while the bacterial species in mechanized Huangjiu were relatively few ( Xie et al, 2021 ), and the quality of fermented mash was directly related to the content of Lactobacillus .…”

“…The wheat Qu of manual Huangjiu is naturally cultivated and mixed with pure breeds. Due to the different types and dosages of wheat Qu , there are significant differences in the types and abundance of microorganisms in different fermented mash ( Xie et al, 2021 ), resulting in differences in metabolic pathways between manual Huangjiu and mechanized Huangjiu in the post-fermentation stage.…”

“…In the manual pressing, the moisture and air in the raw wheat Qu are higher ( Xie et al, 2021 ), which is conducive to the early growth of yeast and fungi, and Aspergillus enzyme in the manual Qu quickly established the growth advantage. Manual operation also brought more bacterial infection to raw wheat Qu, resulting in higher microbial diversity in finished manual wheat Qu.…”

“…Traditional manual Huangjiu uses naturally cultivated wheat Qu and yeast as saccharifying and fermenting agents, and the fermentation cycle is generally 72 days. In the first fermentation stage, pottery jar is used as fermentation container, and in the second fermentation stage (post-fermentation), pottery jar is used as fermentation container ( Xie et al, 2021 ). The fermentation of Huangjiu requires a post-fermentation process with a long time at low temperature.…”

The way of Qu‐making significantly affected the volatile flavor compounds in Huangjiu (Chinese rice wine) during different brewing stages

“…DNA extraction and sequencing were performed according to Xie, GF method (Xie et al., 2021). A linear relationship was established between the sequencing data and flavor substances by partial least squares regression.…”