Effects of traditional starter and the Round‐Koji‐Maker starter on microbial communities and volatile flavours of Chi‐Flavour Baijiu

Abstract

Summary The mechanised starter‐making has been widely applied to the brewing of Baijiu. However, the effect of mechanical production on microbial flora and volatile flavour compounds of Chi‐Flavour Baijiu was still unknown. This study was to investigate the differences in microbial flora and volatile flavours between the traditional starter Baijiu (BQ) and Round‐Koji‐Maker Starter Baijiu (SQ) during brewing. The results showed that the contents of alcohol, total acidity and organic acid in BQ were significantly higher than those in SQ at the end of fermentation (P < 0.05). The dominant bacterial and fungal genera in SQ and BQ were Lactobacillus and Saccharomyces, respectively. The relative content of Pediococcus and Weissella in BQ was significantly higher than those in SQ in the prophase of fermentation. In respect of volatile flavours, there were 117 kinds of volatile flavours detected in SQ, higher than 90 kinds of those in BQ during the fermentation. The characteristic volatile flavours of Chi‐Flavour Baijiu were all detected with no significant difference between BQ and SQ, and the difference in flavours mainly came from 2‐methoxy‐4‐methylphenol, ethyl decanoate, (E)‐hept‐2‐enal. Lactobacillus was significantly positively correlated with ethyl decanoate and ethyl benzoate in BQ and phenethyl acetate in SQ. In addition, Candida had a strong positive correlation with β‐phenylethanol and ethyl myristicate in BQ and SQ. This study provides an in‐depth analysis of the difference between traditional and mechanical Xiaoqu starters in Baijiu fermentation and theoretical guidance for the standard production and quality improvement of Chi‐Flavour Baijiu.

Effect of hydrolyzed soybean on the volatile flavors and microbial community in the traditional brewing process of chi‐flavor Baijiu

“…The raw materials for fermentation, such as rice, soybeans, Xiaoqu, saccharifying enzyme, and dry yeast, were provided by Guangdong Jiujiang Distillery Co., Ltd. Hydrolysis of soybean powder was performed at 45 • C for 10 h by 0.4% acid protease, 0.3% neutral protease, and 0.4% lipase (Shandong Lonct Enzymes Co., Ltd.), which was ended by incubating at 100 • C for 10 min. The traditional fermentation method was used to prepare CFB according to previous report (Fei et al, 2023). Briefly, 200 g of rice was washed and steamed, then cooled to 35 • C, which was mixed with digested soybeans (3.0 g), Xiaoqu (20%), saccharifying enzyme (1%), and dry yeast (2%).…”

“…Chi-flavor Baijiu (CFB), originated from the Pearl River Delta region of Guangdong Province, was a very distinc-tive liquor with the style of "unique soybean flavor, clean and refreshing aftertaste" (Fei et al, 2023;Zhao, Liang, et al, 2022). Chi-flavor liquor was an independent aroma liquor, which was different from the rice-flavor liquor.…”

“…Rice was used as the main raw material for the production of CFB, but a certain amount of soybean was also added as raw materials in many traditional processes (Fei et al, 2023;Wang et al, 2018). Soybean, as an important nitrogen source in the fermentation, had important effect on the growth and metabolism of microorganisms in the fermentation process of chi-flavor liquor (Zhang et al, 2015).…”

“…Meanwhile, the soybean was rich in unsaturated fatty acids such as linoleic, oleic, and linolenic acids, which had influences on the fatty acid composition of Saccharomyces cerevisiae and contents of major volatile compounds, including higher alcohols, mediumchain fatty acids (butanoic, hexanoic, and octanoic acids), and acetate esters (isoamyl acetate and 2-phenylethyl acetate) in wine (Duan et al, 2015). Meanwhile, there was no uniform statement about the characteristic aroma components of chi-flavor liquor, which is due to the complexity of chi-flavor components and the instability of microbial fermentation (Fan et al, 2015;Fei et al, 2023). In order to control and enhance the flavor of chi-flavor liquor, it was necessary to explore the complex relationship among traditional brewing technology, microorganisms, and volatile flavor substances.…”

“…In order to control and enhance the flavor of chi-flavor liquor, it was necessary to explore the complex relationship among traditional brewing technology, microorganisms, and volatile flavor substances. However, the current research on CFB mainly focused on the production technology, brewing microorganisms, and flavor components (Fei et al, 2023;Zhao, Liang, et al, 2022), and there were few studies related to the fermentation materials, especially soybean.…”