Characteristics of the Microbial Community in the Production of Chinese Rice-Flavor Baijiu and Comparisons With the Microflora of Other Flavors of Baijiu.

Yuanliang Hu,Xiaomin Zhang,Luyao Wang,Nan Peng,Junming Tu,Zongjie Zhang,Tongwei Guan,Shumiao Zhao,Xinyi Lei,Xiang Yu,Yunxiang Liang

doi:10.3389/fmicb.2021.673670

Abstract

Rice-flavor baijiu is one of the four basic flavor types of Chinese baijiu. Microbial composition plays a key role in the classification of baijiu flavor types and the formation of flavor substances. In this study, we used high-throughput sequencing technology to study the changes of microbial community in the production of rice-flavor baijiu, and compared the microbial community characteristics during production of rice-, light-, and strong-flavor baijiu. The results showed that the species diversity of bacteria was much higher than that of fungi during the brewing of rice-flavor baijiu. The bacterial diversity index first increased and then decreased, while the diversity of fungi showed an increasing trend. A variety of major microorganisms came from the environment and raw rice materials; the core bacteria were Lactobacillus, Weissella, Pediococcus, Lactococcus, Acetobacter, etc., among which Lactobacillus was dominant (62.88–99.23%). The core fungi were Saccharomyces (7.06–83.50%) and Rhizopus (15.21–90.89%). Temperature and total acid content were the main physicochemical factors affecting the microbial composition. Non-metric multidimensional scaling analysis showed that during the fermentation of rice-, light-, and strong-flavor baijiu, their microbial communities formed their own distinct systems, with considerable differences among different flavor types. Compared with the other two flavor types of baijiu, in the brewing process of rice-flavor baijiu, microbial species were fewer and dominant microorganisms were prominent, which may be the main reason for the small variety of flavor substances in rice-flavor baijiu. This study provides a theoretical basis for the production of rice-flavor baijiu, and lays a foundation for studying the link between baijiu flavor formation and microorganisms.

Highlights

Chinese baijiu is a traditional alcoholic beverage and one of the six major distilled spirits in the world (Wu J. et al, 2017; He et al, 2019)
11 major flavor components were identified in this study, which might be the main reason for the weak aroma of rice-flavor baijiu
The results showed that the species diversity of bacteria was much higher than that of fungi in the brewing process of rice-flavor baijiu, and the bacterial diversity index first increased and decreased, while the fungal diversity showed an increasing trend

Summary

Introduction

Chinese baijiu is a traditional alcoholic beverage and one of the six major distilled spirits in the world (Wu J. et al, 2017; He et al, 2019). Compared with other distilled spirits, such as whisky and brandy, baijiu is generally produced by natural solidstate fermentation with a mixture of microbial species (yeasts, bacteria, and molds), with saccharification and fermentation taking place at the same time, and the base liquor being obtained by solid-state distillation. Other distilled spirits undergo saccharification and fermentation separately, enzyme preparation is added for saccharification, one or more yeasts are inoculated for liquid fermentation, and the base liquor is obtained by liquid distillation (Jin et al, 2017; Wanikawa, 2020). Due to the differences in the selection of raw materials, types of distillers, and production processes, etc., 12 types of baijiu have been developed in China, with four main flavor types; sauce, strong, light, and rice flavors (Yin et al, 2020a; Gao et al, 2021). At the end of saccharification, water for brewing is added, semi-solid fermentation is carried out for approximately 13 days, and the base liquor is obtained by distillation (Li et al, 2019)

Methods

Results

Discussion

Conclusion