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

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 <i>Pediococcus</i>, <i>Saccharomycopsis</i>, <i>Rhizopus</i>, <i>Weissella</i>, and <i>Limosilactobacillus</i> 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 <i>Saccharomyces</i>, <i>Cyberlindnera</i>, <i>Pichia</i>, <i>Pediococcus</i>, <i>Pseudomonas</i> and <i>Lactococcus</i>. The biosynthesis of flavonoids was potentially correlated with <i>Pediococcus</i>, <i>Lactococcus</i>, and <i>Lactiplantibacillus</i>. These findings contribute to monitoring product quality and optimizing the processing techniques of THHJ.