Evaluation of the spatial distribution and dynamic succession of microbial community and quality properties during fermentation in Chinese medium‐temperature Daqu

Abstract

The spatial characterization of qualities and microbial community of Chinese Baijiu Daqu during solid-state fermentation remains unclear. The physicochemical indexes and microbial of the core (CDB) and the surface (SDB) of medium-temperature Daqu (MT-Daqu) at eight fermenting stages were investigated. The results indicated the difference in physicochemical indices, enzymatic activities, and starch granule fracture between the CDB and SDB. The dominant bacteria were Lactobacillus, Weissella, Pediococcus, and Methylobacterium in the SDB, as Staphylococcus, Bacillus, Thermoactinomyces, and Undibacterium in the CDB. The dominant fungi were Dipodascus, Wickerhamomyces, Hyphopichia, and Saccharomyces in the SDB, like Aspergillus, Thermoacscus, Theromyces, and Candida in the CDB. Redundancy analysis (RDA) showed that different factors strongly affected the bacteria and fungi in the SDB and CDB, respectively. The temperature, moisture, and starch content were the critical factors for the microbial composition of Daqu. This study provides further valuable information for knowing the fermentation mechanism of MT-Daqu. Novelty impact statement1. This study provided information on the spatial characterization of qualities and microbial community of Chinese Baijiu Daqu during solid-state fermentation of medium-temperature Daqu (MT-Daqu).2. This study revealed the difference between the surface brick samples (SDB) and the core brick samples (CDB) in the fermentation process of Daqu, which increased the diversity of fermentation.3. The temperature, moisture, and starch content were the critical factors in influencing the difference between Daqu microorganisms of the core (CDB) and the surface (SDB) of medium-temperature Daqu (MT-Daqu).

Relationship between dynamic changes of microorganisms in Qupi and the quality formation of Fengxiangxing Huairang Daqu

“…For instance, different raw materials and their proportions, the shape of the Qupi, the geographical location of the fermentation room, environmental temperature and humidity, fermentation time of Daqu, etc., contribute to different aromas in Daqu, such as Qingxiangxing, Nongxiangxing, Jiangxiangxing, and Fengxiangxing ( He et al, 2022 ; Zhang et al, 2023 ; Tang et al, 2024 ). Based on the maximum temperature the Qupi can reach during Daqu preparation, Daqu can be divided into high-temperature Daqu whose maximum temperature is 60°C–65°C, low-temperature Daqu whose maximum temperature is 40°C–50°C, and middle-temperature Daqu whose maximum temperature is 55°C–60°C ( Fu et al, 2021 ; Yang L. et al, 2021 ; Yang Y. et al, 2021 ; Ding et al, 2022 ; Zhou et al, 2022 ). The process of transforming Qupi into Daqu involves three phases: the warming period, the high-temperature period, and the maturation period.…”

“…The process of transforming Qupi into Daqu involves three phases: the warming period, the high-temperature period, and the maturation period. Among them, the microbial community in the warming period is the richest; the thermophilic and heat-resistant microflora mainly survive and proliferate in the high-temperature period, and the heat-resistant microflora recover and reproduce in the maturation period ( Fu et al, 2021 ; Ding et al, 2022 ; Huang et al, 2023 ). As such, the evolution of the microbial community in Daqu significantly affects and contributes to the dynamic changes in its fermentation characteristics and volatiles, thus affecting the quality of Daqu.…”