Sauce-aroma Baijiu is a distilled Baijiu well-known in China, and features a unique sauce-aroma style formed by a complex producing process in a specific geographical environment. However, there are few comprehensive reviews of the factors influencing the formation of its flavor. To this end, reviews are hereby carried out over factors including different components in brewing raw materials, geographical environment of Baijiu production, brewing technology including the production of high-temperature Daqu and the brewing process, storage technology including the type of storage containers, storage time and storage temperature involved in the production of Sauce-aroma Baijiu. In addition, the effects of these factors on the flavor formation of Sauce-aroma Baijiu are also revealed, providing references and forging a foundation for stabilizing and improving the quality of Sauce-aroma Baijiu.

Baijiu is a unique and traditional distilled liquor in China. Flavor plays a crucial rule in baijiu. Up to now, the research on the flavor of baijiu has progressed from the identification of volatile compounds to the research on key aroma compounds, but the release mechanism of these characteristic compounds is still unclear. Meanwhile, volatile compounds account for only a tiny fraction, whereas ethanol and water account for more than 98% of the content in baijiu. By summarizing the ethanol–water hydrogen bond structure in different alcoholic beverages, it was found that flavor compounds can affect the association strength of the ethanol–water hydrogen bond, and ethanol–water can also affect the interface distribution of flavor compounds. Therefore, the research on ethanol–water microstructure in baijiu is helpful to realize the simple visualization of adulteration detection, aging determination and flavor release mechanism analysis of baijiu, and further uncover the mystery of baijiu.

Even within the same round of stacked fermentation, variations among production workshops can significantly influence microbial communities and physicochemical parameters. In this study, stacked fermented grains from the fourth round of sauce-flavor Baijiu production were utilized to explore the impact of spatial variations on fermentation. High-throughput sequencing technology was employed to comprehensively analyze the microbial community composition and its dynamic changes during the fourth cycle of stacked fermentation in sauce-flavor Baijiu across different workshops. Our results revealed that the predominant genera in both workshops included Saccharomycetales, Thermomyces, Monascus, Ascomycota, Kroppenstedtia, Bacillus, and Virgibacillus. Differences in physicochemical factors during the fermentation process led to distinct microbial successions among workshops. Key drivers of dominant microbial community succession, such as glucose, starch, ethanol, and temperature, were identified during the fourth round of stacked fermentation. Differences in the types and contents of significant flavor substances in different workshops are related to the complex role of the microbial community. Acetic acid is the most different flavor substance in both workshops, and the content of acetic acid affects the synthesis of ethyl ester substances, which has significant correlation with the regulation of fungal communities, especially Saccharomycetales. These findings provide valuable insights into the brewing mechanisms of the stacked fermentation process and offer guidance for formulating more refined control strategies to optimize the liquor-making process.

This study systematically investigated the key aroma compounds across seven consecutive production rounds of Sauce-flavor base baijiu from the Tianfu region using an integrated molecular sensory approach. GC-MS profiling tentatively identified 232 volatile compounds by NIST library matching, while 58 low-content and 12 high-content aroma compounds were quantitatively determined by GC-MS/MS and GC-FID, respectively. Thirty-seven compounds showed literature-based OAV values ≥ 1 and were selected as candidate aroma-active compounds for further sensory evaluation. Aroma recombination and omission experiments provided further sensory evidence for the relevance of 13 aroma compounds, including ethyl furfuryl ether, 1-propanol, ethyl isovalerate, and acetoin, to the aroma profiles of representative production rounds. Quantitative analysis revealed marked round-dependent variations in higher alcohols, esters, and acids, highlighting dynamic changes in the volatile composition of Sauce-flavor base baijiu across successive production rounds. This work provides a quantitative and sensory basis for understanding aroma variation across production rounds within the investigated Sauce-flavor baijiu production system and may provide a reference for subsequent flavor evaluation and process optimization.