Biotechnological approaches for targeted strain screening and enhancement of Daqu for quality baijiu production

Chinese baijiu is a traditional and one of the oldest fermented liquors that consumers prefer because of its distinctive sensory profile. The process of baijiu fermentation begins with the production of Daqu, a fermentation starter made from a solid-state fermentation of grains. Daqu is a key ingredient for baijiu since the sensory characteristics of baijiu are greatly influenced by the physiochemical properties including temperature, moisture, pH, and the content of aromatic and flavor compounds as well as biological properties such as the microbial composition, stability, and diversity of Daqu. However, the Daqu microbial structure regulates the baijiu quality the most as it is responsible for the extent of saccharification, alcohol fermentation, and flavor generation during the baijiu-making process. Thereby, several biotechnological approaches are used to improve the microbial community structure of Daqu to ultimately enhance the baijiu quality. Some of the most common and effective approaches including fortification, bioaugmentation, microbial consortia development, and omics techniques are reviewed in this paper to provide insights into the current state of knowledge in this area, including the implications of modified Daqu and its impact on baijiu quality.