Differences in the Quality of Jiang-Flavor Base Baijiu Brewed from Different Varieties of Sorghum

In this study, three varieties of sorghum (Hongyingzi, Lunuo 18, and Liangnuo 1), which vary in quality, were used to brew Jiang-flavor base Baijiu. The differences in the physicochemical factors of fermented grains and the important flavor compounds of base liquor from different rounds of fermentation were compared among the varieties. The results showed that the moisture content of fermented grains from Liangnuo 1 in the first 4 rounds of fermentation was significantly higher than that of any other group (P < 0.05). The acidity of fermented grains from Hongyingzi in the first 7 rounds was the highest, followed by Lunuo 18 and Liangnuo 1, with significant differences being observed (P < 0.05). Besides, the reducing sugar content of fermented grains from Liangnuo 1 after stacking fermentation and cellar fermentation was significantly higher than that of Hongyingzi and Lunuo 18 (P < 0.05). A total of 75 major volatile flavor compounds were quantitatively analyzed by gas chromatography with hydrogen flame ion detection (GC-FID) using an internal standard method, including 24 esters, 16 alcohols, 9 acids and, 13 aldehydes and ketones. A principal component analysis (PCA) plot showed clear separation of Liangnuo 1 base Baijiu samples from the third, fourth and sixth rounds of fermentation according to their flavor composition, and the changes in the characteristic flavor compounds in fermented grains from Hongyingzi and Lunuo 18 were similar. A total of 33 flavor components were identified by odor activity value (OAV) analysis, and 17 important differential components were selected by orthogonal partial least squares-discriminant analysis using the cutoff of variable importance in projection (VIP) score > 1. This study systematically analyzed the differences between the fermentation parameters of different sorghum varieties and the flavor substances of base liquor, which could provide a theoretical basis for the screening of raw materials for liquor production.