Differences in the Composition of Flavor Compounds of Nongxiangxing Baijiu Brewed from Different Varieties of Sorghum and Its Influencing Factors

In two Baijiu-making distilleries, multiple batches of Nongxiangxing Baijiu were produced from four varieties of brewing sorghum. Using high performance gas chromatography, the flavor compounds in Baijiu samples were detected, and differences in their composition and influencing factors were investigated. It was found that distillery, brewing batch, and sorghum variety all affected the composition of flavor compounds, where brewing batch had a greater influence than sorghum variety. With respect to Baijiu samples of different varieties of sorghum, the types and quantities of differential flavor compounds varied greatly with distilleries and brewing batches, and six reliable differential flavor compounds were obtained, including 2-methyl-1-butanol, sec-butyl alcohol, isobutanol, isoamyl alcohol, methanol, and propionic acid. The fusel oil content in Baijiu sample produced by northern hybrid japonica sorghum was significantly higher than that in glutinous sorghums (Jinuoliang No.1 and Jinuoliang No.2). The acidity of Jiupei at the beginning of brewing significantly affected the composition of flavor compounds, the amount of esters and aldehydes, and the content of propionic acid and methanol in Baijiu sample (P<0.05). The tannin content of sorghum significantly affected the contents of aldehydes and isobutanol, and the amylopectin content affected the contents of sec-butyl alcohol (P<0.05). On the basis of the physicochemical properties of the Jiupei and sorghum, multiple regression equations were obtained to predict the differential flavor compounds, with an explanatory degree ranging from 23.00% to 51.00% and 14.60% to 18.80%, respectively. The study laid the foundation for improving and popularizing brewing sorghum varieties as well as optimizing and perfecting the brewing process parameters.