# Microbial Communities, Volatile Flavor Profiles and Metabolomic Characteristics During Traditional Hakka Huangjiu Fermentation

## TL;DR

This study explores how microbial communities and their byproducts influence the flavor and quality of a traditional Chinese rice wine during fermentation.

## Contribution

The study provides a detailed multi-omics analysis of microbial dynamics and their correlation with flavor compounds in Traditional Hakka Huangjiu fermentation.

## Key findings

- Pediococcus, Saccharomycopsis, Rhizopus, Weissella, and Limosilactobacillus were dominant during saccharification.
- 737 volatile compounds and 4370 metabolites were identified during post-fermentation.
- Phenylethyl alcohol was found to be the most influential flavor compound, linked to several microbial genera.

## Abstract

The brewing of Traditional Hakka Huangjiu (THHJ) is usually divided into saccharification and post-fermentation. Microbial succession during saccharification is the major factor influencing the development of the volatile and non-volatile substances in THHJ during post-fermentation. This study systematically investigated the dynamic changes in microbial community, volatile substances and microbial metabolites by using absolute quantitative sequencing and multi-omics analysis. This study also reported that the correlation between microorganisms and substance biosynthesis was analyzed using PICRUSt. Absolute quantitative sequencing results showed that Pediococcus, Saccharomycopsis, Rhizopus, Weissella, and Limosilactobacillus were the dominant microbial genera during saccharification. 737 volatile compounds (170 esters, 94 hydrocarbons, 82 organoheterocyclic compounds) and 4370 metabolites (18 organic acids, 22 amino acids, 1124 peptides and 9 categories of functional compounds) were identified throughout the post-fermentation period. Sensory profiling revealed six main flavor attributes (Balsamic, sweet, rose, green, fruity, bitter) in THHJ and phenylethyl alcohol exerted the most prominent effect on the overall flavor of THHJ. Correlation analysis revealed that the biosynthesis of phenylethyl alcohol was potentially correlated with Saccharomyces, Cyberlindnera, Pichia, Pediococcus, Pseudomonas and Lactococcus. The biosynthesis of flavonoids was potentially correlated with Pediococcus, Lactococcus, and Lactiplantibacillus. These findings contribute to monitoring product quality and optimizing the processing techniques of THHJ.