Detection and Source Analysis of Terpenoids in Nongxiangxing Baijiu during the Brewing Process

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used for the detection of terpenoids in the raw materials, Daqu, pit mud, fermented grains and base liquor during the brewing process of Nongxiangxing baijiu. Totally 19 terpenoids were detected from the nine raw materials, and their total concentration was 1338.22 μg/kg. In addition, 18 terpenoids were detected in Daqu at eight time points during fermentation with a total concentration of 2020.32 μg/kg. A total of 13 terpenoids were detected in pit mud from 10 different cellars with a total concentration of 2167.89 μg/kg. Eight terpenoids were detected in fermented grains at four time points with a total concentration of 702.68 μg/kg. Nine terpenoids were detected in two groups of base liquor with a total concentration of 338.56 μg/kg. Comparative analysis showed that two of the nine terpenoids came from the raw materials, three came from Daqu, and two were converted from other substances due to high temperatures during the steaming process.