Effects of aging on the quality of roasted sesame-like flavor Daqu

Abstract

Background: Daqu, the saccharification, fermentation, and aroma-producing agents for Baijiu brewing, is prepared using a complex process. Aging is important for improving the quality of Daqu, but its impact has rarely been studied. This study investigated changes in the physicochemical properties, flavor compounds, and microbial communities during aging of Daqu with a roasted sesame-like flavor. Results: The physicochemical properties changed continuously during aging to provide a high esterifying activity. Aging removed unpleasant flavor compounds and helped to stabilize the flavor compounds in mature Daqu. A high-throughput sequencing approach was used to analyze the changing composition of the microbial communities during aging. Aging helped to modify the microbial population to produce better Baijiu by eliminating low-abundance microbial communities and optimizing the proportion of predominant microbial communities. Nine genera of prokaryotic microbes formed the core microbiota in Daqu after aging. Regarding eukaryotic microbes, Zygomycota, the predominant community, increased in the first 2 months, then decreased in the third month of aging, while Ascomycota, the subdominant community, showed the opposite behavior. Absidia, Trichocomaceae_norank and Rhizopus were the predominant genera in the mature Daqu. Conclusions: Significant correlations between microbiota and physicochemical properties or flavor compounds were observed, indicating that optimizing microbial communities is essential for aging Daqu. This study provides detailed information on aging during Daqu preparation.

Understanding the Shifts of Microbial Community and Metabolite Profile From Wheat to Mature Daqu

“…High-intensity Staphylococcus produced volatile flavors such as 3-methyl-1-butanol, 2-butanone, and acetoin, which might play important roles in Baijiu production (Guan et al, 2020). Bacillus could convert starch and proteins into glucose and amino acids by secreting amylase, protease, cellulases, glucanases, and other enzymes, thereby contributing to the development of volatile flavors (Fan G. S. et al, 2020). At the same time, F-Daqu and M-Daqu showed significant differences in fungal community structure.…”

“…The pH was measured using a pH meter positioned in the slurry (Zheng et al, 2012). The activity of glucoamylase and protease were determined according to the 3,5-dinitrosalicylic acid (DNS) method and Folin-phenol method, respectively (Fan G. S. et al, 2020). One unit of glucoamylase activity was defined as the amount of Daqu required for the liberation of 1 µmol glucose per minute in PBS buffer (50 mM, pH 6.5) at 40 • C. One unit of protease activity was defined as the amount of Daqu required for the liberation of 1 mg tyrosine per minute in PBS buffer (50 mM, pH 7.0) at 40 • C (Li et al, 2017).…”

Isolation and Identification of a High-Yield Ethyl Caproate-Producing Yeast From Daqu and Optimization of Its Fermentation

“…Baijiu, a typical Chinese traditional fermented food, is made from sorghum, wheat, and/or rice by a complex fermentation process using natural mixed-culture starters (named Daqu) (Fan et al, 2020a). One of those starters is Daqu, which harbors many microorganisms for Baijiu brewing, and is used as a saccharifying and fermenting agent for Baijiu production.…”

“…One of those starters is Daqu, which harbors many microorganisms for Baijiu brewing, and is used as a saccharifying and fermenting agent for Baijiu production. Daqu is made from cereals such as wheat, barley, and peas by spontaneous solid-state fermentation in an open environment (Fan et al, 2020a). During Daqu production, the raw materials are colonized by networks of microorganisms from the environment.…”

Diversity, Enzyme Production and Antibacterial Activity of Bacillus Resource in Sesame-Flavored Liquor Daqu

“…High-temperature fermentation of Daqu is the key to the special avor of sesame-avored liquor. Daqu is obtained through a complex fermentation process (Fan et al 2020), made of corn, sorghum, wheat, etc. As a saccharifying agent for liquor fermentation (Tian et al 2020), Daqu provides raw materials such as enzymes and avor substances for liquor fermentation.…”