This study investigated the effects of different methods of Bacillus inoculation (separate cultures, co-culture, and no inoculation) on the sensory characteristics and flavor pyrazine compounds of high-temperature Daqu. During the fermentation process, total acidity and moisture content decreased progressively, and sensory attributes of Bacillus-fortified Daqu were superior to those of the control group. For finished Daqu, the total content of pyrazine compounds was significantly higher in the experimental groups (3376.89 μg/g for fortified Daqu Ⅱ, 2842.47 μg/g for fortified Daqu Ⅰ) than in the control group (1868.78 μg/g). A total of 24 prokaryotic and 16 eukaryotic genera were identified as dominant microbiota. The abundance of Bacillus, Thermomyces, and Thermoascus in fortified Daqu was higher than that in the control group. A total of 21 prokaryotic and 19 eukaryotic differentially abundant microorganisms were identified. In summary, the inoculation of Bacillus seed culture contributed to improved sensory attributes, enhanced microbial diversity to some extent, and increased the concentration of pyrazine compounds, thereby improving the overall quality of high-temperature Daqu.

This study systematically investigated the droplet evaporation behavior and deposition pattern characteristics of Jinsha Jiangxiangxing Baijiu, and analyzed the correlation between the deposition patterns and sensory quality. The results showed that during evaporation, all Baijiu samples of different quality grades exhibited particle self-assembly, with particles moving and depositing under the influence of the internal fluid flow within the droplet. The deposition patterns left at the interface after droplet evaporation significantly varied with the degree of self-assembly and fluid flow effects. High-quality samples (Grades Ⅰ-Ⅲ) showed a greater number of self-assembled particles at the three-phase contact line, while low-quality samples (Grade Ⅳ and Ⅴ) had fewer particles. The observation of evaporation modes revealed that Grades Ⅰ-Ⅲ primarily exhibited a mixed evaporation mode of constant contact angle (CCA) and constant contact radius (CCR), accompanied by pronounced “pinning-slipping” phenomena, resulting in irregular multi-ring deposition patterns with more abundant particle distribution within the rings. In contrast, Grades Ⅳ and Ⅴ mainly followed the CCR evaporation mode, forming typical coffee-ring structures with sparse particle distribution within the rings. Image analysis indicated a significantly positive correlation between the integrated optical density of deposition patterns and sensory scores, validated using various commercially available Baijiu products. Gas chromatography-mass spectrometry (GC-MS) analysis suggested that this correlation was closely associated with the content of long-chain fatty acid ethyl esters in Baijiu. This study provides a visualization-based method for evaluating the quality of Jiangxiangxing Baijiu through deposition patterns, offering a new strategy for the rapid quality evaluation of Jiangxiangxing base and finished Baijiu.

In this study, high-throughput sequencing technology, linear discriminant analysis effect size (LEfSe) and redundancy analysis (RDA) were used to investigate the structure of prokaryotic and eukaryotic communities, the differential microbial communities, and the relationship between microorganisms and physicochemical factors in pit mud (PM) from cellars of different ages (5, 10 and 20 years) and from different spatial locations of cellars. The results showed that the diversity of both prokaryotic and eukaryotic microorganisms was higher in the five-year-old PM than in the 10- and 20-year-old PM. Among all samples, a total of 37 phyla, 83 classes, 176 orders, 306 families and 629 genera of prokaryotic microorganisms were detected, with five phyla being the dominant ones. Totally 12 phyla, 37 orders, 74 families, 160 families and 282 genera of eukaryotic microorganisms were detected, including three phyla and 15 genera being dominant. LEfSe identified 12 differential prokaryotic genera and 15 differential eukaryotic species, and the differential microbial communities of each sample played an important role in the fermentation process of baijiu. The results of physicochemical analysis showed that the pH of the PM samples varied from 3.66 to 5.20, and the effective phosphorus content of PM was significantly different among locations. RDA analysis showed that Lactobacillus, unclassified_f__Aspergillaceae, and Thermomyces were negatively correlated with moisture, ammonia nitrogen, and effective phosphorus contents, and Methanobacterium, Clostridium_sensu_stricto_12, Caproiciproducens, Methanobrevibacter, Cryptococcus_f__Tremellaceae and Apiotrichum were positively correlated with moisture, pH, ammonia nitrogen, and effective phosphorus. This study provides theoretical support for the establishment of daily PM maintenance as well as high-quality PM domestication and production.