Su Chang, Zhang Kai-Zheng, Cao Xin-Zhi, Yang Jian-Gang
College of Bioengineering, Sichuan University of Science & Engineering, Zigong 643000, China; College of Food Science, Sourthwest University, Chongqing City 400715, China.
College of Bioengineering, Sichuan University of Science & Engineering, Zigong 643000, China.
Food Res Int. 2020 Nov;137:109425. doi: 10.1016/j.foodres.2020.109425. Epub 2020 Jun 6.
Xiaoqu liquor is a type of distilled spirit in China prepared on a small scale from a small solid starter culture. Although this liquor is popular in southwestern China, it can have a dull taste, limiting its market. To improve the flavour profile of Xiaoqu liquor, we selected two functional yeast strains (Saccharomycopsis fibuligera and Saccharomyces cerevisiae) from Zaopei (fermented grain) of Baijiu liquor and used them for Xiaoqu liquor fermentation. Compared with traditional Xiaoqu (Starter), bioaugmentation inoculation increased the glucoamylase and acidic protease activities and the ethanol synthesis rate, while decreasing the acidity of the Zaopei (fermented grains) in the early stage of fermentation. By the end of the fermentation process, the alcohol and ester content had also increased by 42.5% and 11.8%, respective, and that of aldehydes and ketones, and heterocyclic compounds decreased by 73.7% and 77.1%, respectively. Traditional isolation and high-throughput sequencing were employed to analyse the microorganisms in the Zaopei. Bioaugmentation inoculation increased the microbial diversity of Xiaoqu liquor during the fermentation process. The dominant fungus during fermentation using the two types of starter cultures was S. cerevisiae, whereas the dominant bacteria was Pseudomonas, followed by Bacillus, Weissella, Lactobacillus, and Bacteroides. Principal component analysis of the bacterial community structure and flavour substances in the Zaopei produced using the two strains revealed that there were few differences between the two liquors and that inoculation with functional yeasts may not change the flavour substances in Xiaoqu liquor. However, correlation analysis showed that Escherichia Shigella, Terrisporobacter, Bacillus, Clostridium, and Prevotellaceae are the main microorganisms in the Xiaoqu liquor fermentation process. These results lay the foundation to improve the quality of Xiaoqu liquor.
小曲酒是中国一种用小曲固态发酵、小规模酿造的蒸馏酒。尽管这种酒在中国西南部很受欢迎，但它的口感可能较为寡淡，限制了其市场。为改善小曲酒的风味，我们从白酒糟醅中筛选了两株功能酵母菌株（扣囊复膜酵母和酿酒酵母）用于小曲酒发酵。与传统小曲（酒曲）相比，生物强化接种提高了糖化酶和酸性蛋白酶的活性以及乙醇合成速率，同时在发酵前期降低了糟醅的酸度。到发酵结束时，酒精和酯类含量分别增加了42.5%和11.8%，而醛类、酮类和杂环化合物的含量分别降低了73.7%和77.1%。采用传统分离方法和高通量测序技术分析了糟醅中的微生物。生物强化接种增加了小曲酒发酵过程中的微生物多样性。使用这两种酒曲发酵时，发酵过程中的优势真菌是酿酒酵母，优势细菌是假单胞菌，其次是芽孢杆菌、魏斯氏菌、乳酸杆菌和拟杆菌。对两种菌株发酵产生的糟醅中细菌群落结构和风味物质进行主成分分析表明，两种酒之间差异不大，接种功能酵母可能不会改变小曲酒的风味物质。然而，相关性分析表明，埃希氏菌属、志贺氏菌属、地芽孢杆菌属、梭菌属和普雷沃氏菌科是小曲酒发酵过程中的主要微生物。这些结果为提高小曲酒品质奠定了基础。
