Simulated Fermentation of Strong-Flavor Baijiu through Functional Microbial Combination to Realize the Stable Synthesis of Important Flavor Chemicals

Abstract

The solid-state fermentation of Baijiu is complicated by the co-fermentation of many microorganisms. The instability of the composition and abundance of the microorganisms in the fermentation process leads to fluctuations of product quality, which is one of the bottleneck problems faced by the Strong-flavor Baijiu industry. In this study, we established a combination of functional microorganisms for the stable fermentation of the main flavor compounds of Baijiu, including medium and long-chain fatty acid ethyl esters such as hexanoic acid, ethyl ester; butanoic acid, ethyl ester; octanoic acid, ethyl ester; acetic acid, ethyl ester; 9,12-octadecadienoic acid, ethyl ester; and decanoic acid, ethyl ester in the fermented grains. Our study investigated the effects of microbial combinations on the fermentation from three aspects: microbial composition, microbial interactions, and microbial association with flavor compounds. The results showed that the added functional microorganisms (Lactobacillus, Clostridium, Caproiciproducens, Saccharomyces, and Aspergillus) became the dominant species in the fermentation system and formed positive interactions with other microorganisms, while the negative interactions between microorganisms were significantly reduced in the fermentation systems that contained both Daqu and functional microorganisms. The redundancy analysis showed that the functional microorganisms (Lactobacillus, Saccharomyces, Clostridium, Cloacibacterium, Chaenothecopsis, Anaerosporobacter, and Sporolactobacillus) showed strong positive correlations with the main flavor compounds (hexanoic acid, ethyl ester; lactic acid, ethyl ester; butanoic acid, ethyl ester; acetic acid, ethyl ester; and octanoic acid, ethyl ester). These results indicated that it was feasible to produce Baijiu with a functional microbial combination, and that this could promote stable Baijiu production.

Identification of regionalmarkers based on the flavor molecular matrix analysis of sauce‐aroma style baijiu

“…Among them, four esters ((i) produced by bacteria converting acetic acid into butyric acid or caproic acid through metabolism and then reacting with ethanol; (ii) produced by yeast directly using grain) 38 played an important role in distinguishing baijiu production regions and the fact is that Saccharomyces mainly produced ethanol which served as the precursor for synthesizing the ethyl esters during fermentation. 39 The great differences in microorganisms are mainly related to the geographical environment in various production regions, which fully confirmed their reliability as regional markers. Furthermore, PCA of the nine potential regional markers was performed to assess their ability to differentiate between samples from different regions (Fig.…”

“…In detail, propyl hexanoate was the most important regional marker identified by all methods, and the other potential regional markers were ethyl octanoate, ethyl 2‐methylpropanoate, propyl acetate, ethyl heptanoate, ethyl trans ‐4‐decenoate, 2‐nonanone, heptanoic acid and butyl hexanoate. Among them, four esters ((i) produced by bacteria converting acetic acid into butyric acid or caproic acid through metabolism and then reacting with ethanol; (ii) produced by yeast directly using grain) 38 played an important role in distinguishing baijiu production regions and the fact is that Saccharomyces mainly produced ethanol which served as the precursor for synthesizing the ethyl esters during fermentation 39 . The great differences in microorganisms are mainly related to the geographical environment in various production regions, which fully confirmed their reliability as regional markers.…”

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

“…In addition, compounds such as ethyl palmitate, ethyl decanoate, ethyl caprylate, and phenethyl acetate were found to be higher in FMQFB, meanwhile, isoamyl acetate, ethyl caprylate, ethyl caprylate, and phenethyl acetate were discovered to be higher in IQFB. Hence, one can see that the majority of ester aroma compounds in Huangjiu were ethyl esters, which were mainly produced by the esterification reaction of ethanol catalyzed by acetyltransferase [40,41]. Most of the esters produce fruity or floral aromas, which play a positive role in the aroma of Huangjiu.…”

“…ethyl esters, which were mainly produced by the esterification reaction of ethanol catalyzed by acetyltransferase [40,41]. Most of the esters produce fruity or floral aromas, which play a positive role in the aroma of Huangjiu.…”

Comprehensive genomic and metabolomic analysis revealed the physiological characteristics and pickle like odor compounds metabolic pathways of Bacillus amyloliquefaciens ZZ7 isolated from fermented grains of Maotai-flavor baijiu

“…In the brewing process of MFB, microorganisms will produce various flavor compounds or precursors, which will directly affect the sense and quality of MFB ( Xu et al, 2023 ). Such as, pyrazine compounds synthesized by Bacillus contribute to their unique nutty flavor ( Jin et al, 2019 ); the terpenes produced by Mucor make its taste more elegant and refined ( Wang et al, 2015 ).…”