Application of Wickerhamomyces anomalus in Simulated Solid-State Fermentation for Baijiu Production: Changes of Microbial Community Structure and Flavor Metabolism.

Wenhua Wang,Xin Liang,Zhilei Fu,Zhilei Fu,Guangsen Fan,Xiuting Li,Xiuting Li,Baoguo Sun

doi:10.3389/fmicb.2020.598758

Wenhua Wang, Xin Liang + Show 6 more

Open Access

https://doi.org/10.3389/fmicb.2020.598758

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Abstract

Wickerhamomyces anomalus is conducive to the synthesis of ester compounds in brewing the Chinese liquor Baijiu; esters are crucial for the quality of Baijiu. In this study, simulated solid-state fermentation for Baijiu production was used to explore whether artificial addition of W. anomalus could improve the flavor substance in Baijiu, and the underlying mechanisms. Two experimental groups were studied, in which W. anomalus Y3604 (Group A) and YF1503 (Group B) were added, respectively; in the control group (Group C), no W. anomalus was added. Adding strain Y3604 increased the content of esters in fermentation samples, especially ethyl acetate and ethyl caproate, and reduced the content of higher alcohols. Adding strain YF1503 had little effect on the ester content but decreased the content of higher alcohols. The diversity and abundance of prokaryotic genera in Group A and B samples were similar, but there were some differences compared with Group C. The correlations of genera in Group A or B samples were simple compared with group C. Although the predominant eukaryotic genera in the three groups were consistent, the abundance of each gene varied among groups. Based on our findings, bioaugmentation of Baijiu fermentation with W. anomalus will change the ethyl acetate content and cause changes in the levels of other flavor substances. We suggest that the changes in flavor substances caused by the addition of W. anomalus are mainly due to changes in the microbial community structure that result from the addition of W. anomalus.

Highlights

Baijiu is a traditional alcoholic beverage with thousands of years of history in China, and it occupies a unique position in Chinese traditional culture as a pearl of ancient Chinese wisdom (Han, 2016; Jin et al, 2017; Sun et al, 2018a; Song et al, 2020)
The types and contents of flavor substances in the same group changed with the extension of fermentation time, which is mainly caused by metabolism of microorganisms and chemical reactions among flavor substances
The apparent reason is the addition of W. anomalus, but the mechanism may be the metabolic action of the changed microbiotic community and chemical reactions among the different flavor substances generated after the change of microbiota caused by adding W. anomalus

Summary

Introduction

Baijiu is a traditional alcoholic beverage with thousands of years of history in China, and it occupies a unique position in Chinese traditional culture as a pearl of ancient Chinese wisdom (Han, 2016; Jin et al, 2017; Sun et al, 2018a; Song et al, 2020). Volatile compounds play key roles in the flavor of Baijiu (Li et al, 2019), which contains > 1870 flavoring compounds (Liu and Sun, 2018). Because of their low odor thresholds and synergistic effects, esters, with fruit aroma, fragrance, and sweet smell, are the major contributors to the aroma of Baijiu; minor changes in their concentrations can have significant effects on the flavor of the beverage (Fan and Qian, 2006; Chen and Xu, 2010; Li et al, 2017; Fan et al, 2018b). Ethyl lactate, ethyl caproate, and ethyl butyrate have been identified as the main four ethyl esters (MFEEs) in Baijiu, and ethyl acetate is the principal indicator of quality for various types of Baijiu in almost all standards (Fan et al, 2018b)

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