Ecological Risks in Daqu Storage and Their Impact on Baijiu Flavor: Precision Process Strategies for Damage Mitigation While Preserving Aroma

Daqu functions as a core saccharifying and fermenting starter in Baijiu production and acts as a complex microecological reactor in open solid-state fermentation. The formation of Baijiu flavor is closely associated with microbial community assembly, enzymatic activities, and metabolic interactions occurring within Daqu. However, the open production environment also exposes the Daqu system to multiple external disturbances that may influence its microecological stability and fermentation performance. This review summarizes recent advances in understanding the microecology of Daqu, focusing on microbial succession, metabolic pathways related to flavor formation, and environmental factors affecting Daqu quality. Particular attention is given to how external disturbances during production and storage may influence microbial communities, enzymatic functions, and aroma compound formation. Based on current knowledge, a conceptual framework linking environmental factors, microbial community dynamics, metabolic activity, and flavor outcomes is proposed. In addition, strategies for maintaining microecological stability and ensuring flavor consistency are discussed, including environmental management, process optimization, physical control technologies, and integrated quality monitoring systems. Emphasis is placed on combining process control with modern analytical approaches such as multi-omics technologies and process analytical technologies (PAT) to improve traceability and precision management during Daqu production. Overall, this review provides a systematic perspective on the relationships among Daqu microecology, process conditions, and flavor formation and highlights future research directions for achieving stable and controllable Baijiu fermentation systems.