Environmental factors induced metabolome shifts during Laobaigan-flavor Baijiu fermentation

Environmental factors are the key factors affecting the fermentation of traditional fermented foods. However, the effects of environmental factors on flavor metabolism of Laobaigan-flavor Baijiu have not been described. In this study, we applied HS-SPME-GC-MS and physicochemical parameters analysis to reveal the dynamic of volatile flavor compounds and environmental factors, and indicated the effects of environmental factors on the succession of volatile flavor compounds. The fermentation process was divided into three stages: alcohols (628 mg/kg) and acids reached higher in the early stage (0-8 days), while aldehydes existed more in the middle stage (10-17 days) and esters accumulated until the middle (2501 mg/kg) or later (1168 mg/kg) stages (20-29 days). Meanwhile, environmental factors changed rapidly (p < 0.05), and significantly correlated with the formation of flavor compounds at different stages. Among them, pH and protein content were significantly related to esters (| r| > 0.6) esterified by monocarboxylic acid in the middle stage, while esters (|r| > 0.7) synthesized with hydroxyl acid had significant relations with temperature and moisture in the later stage. Our study indicated the correlations between the dynamic of environmental factors and the succession of volatile flavor compounds, and it provided a potential approach to manage environmental factors to improve the fermentation of Baijiu.