Multiple Batches of Fermentation Promote the Formation of Functional Microbiota in Chinese Miscellaneous-Flavor Baijiu Fermentation

Abstract

Baiyunbian baijiu, the most popular miscellaneous-flavor baijiu in China, has been widely consumed for decades. Similar to many Chinese baijiu, Baiyunbian baijiu is fermented in five successive batches every year. Sensory analysis demonstrated that the raw baijiu obtained from the last two fermentation batches always has better quality than that produced from the former three batches. In this study, the microbial compositions of fungi and bacteria in each fermentation batch were investigated via high-throughput sequencing. The results showed that Bacillus, Virgibacillus, and Lactobacillus dominated the bacterial community in the last two batches, and the most prevalent fungi were Paecilomyces, Saccharomyces, and Zygosaccharomyces. In contrast, large percentages of fungi belonging to Thermomyces, Thermoascus, Monascus, and Issatchenkia and prokaryotes belonging to Acetobacter, Lactobacillus, and Thermoactinomyces were observed in the former three fermentation batches. GC-MS analysis revealed that the fermented grains sampled from the latter two batches contained high concentrations of ethyl lactate, 2,3-butanediol and ethyl caproate, which were mainly generated by co-fermentation of Lactobacillus and yeast. The high acidity of the fermented grains in the fourth and fifth fermentation batches as well as the large contents of ethanol and moisture promoted the formation of the functional microbial community. This study provides insight into factors that influenced the baijiu fermentation and is helpful for developing new fermentation techniques with higher baijiu quality.

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

“…At the late stage of fermentation, the anaerobic environment is dominant, the nutrient content decreases, and the acidity and alcoholic content increases, which inhibit the growth of some microorganisms and lead to a decrease in species diversity. The changing pattern of microbial diversity is consistent with that in the brewing of strong- ( Tan et al, 2019 ; Guan et al, 2020 ), mixed- ( Liu and Miao, 2020 ), and light-flavor baijiu ( Dong et al, 2020 ).…”

“…The essence of baijiu-making is the process of microbial growth and accumulation of metabolites, and the synergistic effect among populations is closely related to the flavor and quality of baijiu ( He et al, 2019 ). Saccharomyces can ferment sugars to produce alcohol, and most of them can survive under high-sugar and relatively acidic conditions and enable alcoholization and esterification during the fermentation of baijiu ( Liu and Miao, 2020 ). Among them, Saccharomyces cerevisiae mainly plays an alcohol-producing role and has a strong alcohol-producing capacity ( Wang et al, 2020 ).…”

Integrative Metagenomics–Metabolomics for Analyzing the Relationship Between Microorganisms and Non-volatile Profiles of Traditional Xiaoqu

“…Succinic acid, a main product of the TCA cycle, is known as the “wine skeleton” (Zhang et al, 2017 ) and, when combined with lactic acid, provides the unique sourness and umami taste to the final product. Additionally, lactic acid is the central precursor of ethyl lactate, which is the key flavoring component in liquor (Cai et al, 2019 ; Liu and Miao, 2020 ). Meanwhile, fumaric acid improves the stability and freshness of wine and decreases the level of SO 2 (Morata et al, 2018 ).…”

“…Indeed metagenomic sequencing has been widely applied for the identification of functional microorganisms in fermented foods, including wine (Liu et al, 2019 ), vinegar (Wu L. et al, 2017 ), cheese (Escobar-Zepeda et al, 2016 ), pickles (Jung et al, 2011 ), cocoa beans (Agyirifo et al, 2019 ), and fermented sausages (Ferrocino et al, 2017 ). Furthermore, metabolomics analysis based on gas chromatography (GC), mass spectrometry (MS), high-performance liquid chromatography (HPLC), and nuclear magnetic resonance revealed the metabolite profiles of jiuqu (Tang et al, 2019 ; Wang N. et al, 2019 ) and Baijiu (Huo et al, 2020 ; Jia et al, 2020 ; Liu and Miao, 2020 ). However, former studies on Xiaoqu have primarily focused on microorganisms and volatile flavors (Liu and Sun, 2018 ; Tang et al, 2019 ; Chen C. et al, 2020 ), whereas the correlation between microorganisms and non-volatile metabolites requires further investigation.…”

Effects of ultra-long fermentation time on the microbial community and flavor components of light-flavor Xiaoqu Baijiu based on fermentation tanks

“…As one of the most important brewing processes, fermentation is performed by the synergistic effect of various microorganisms present in the fermented grains ecosystem, consisting of molds, yeasts, and bacteria (Jung et al 2014 ). Up till now, the characterization of the microbial communities of fermented grains is being elucidated with the development of next-generation high-throughput sequencing technology (Huang et al 2020 ; Guan et al 2020 ; Liu and Miao 2020 ). But there are relatively few studies on the relationship between environmental factors and microbial community composition in fermented grains due to the limitation of sampling from the closed fermentation process, especially the effects of ultra-long fermentation time on the microbial community, physicochemical factors, and flavor components in fermented grains are rarely studied.…”