Environmental temperature variations drive the changes of microbial communities to affect Baijiu flavor quality: Case study of Qingxiangxing Baijiu

Environmental temperature is a crucial factor that affects the fermentation quality of Baijiu. In this study, Illumina Miseq sequencingd, Two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-MS), and physicochemical analyses were employed to investigate the microbial communities, flavor compounds, and physicochemical properties during fermentation at different ambient temperatures (10 ± 2 °C in the lower environmental temperature (LT) group and 22 ± 2 °C in the higher environmental temperature (HT) group). The findings demonstrated an augmentation in microbial diversity, ecological network complexity, and utilization of raw materials by microorganisms in HT group. Sensory analysis showed that sensory properties of Baijiu produced by the HT group had a better overall performance. The Baijiu in the HT group exhibited higher quality in terms of sweetness, fruity and floral, whereas the Baijiu in the LT group displayed a greater degree of unpleasant pungency and acidity. 24 flavor compounds were identified with the Variable Importance in Projection (VIP) > 1, and they were the main factors contributing to the differences in Baijiu flavors at two environmental temperatures. Correlation analysis showed that ambient temperature influenced microbial interactions and their correlation with metabolites. This difference showed the quality change of Baijiu driven by different temperatures. These results provide solid data support for optimizing the Baijiu fermentation process under different seasonal temperatures.