Identification of volatile differential markers in strong-aroma Baijiu based on gas chromatography-electronic nose combined with gas chromatography-time-of-flight mass spectrometry.

Abstract

Baijiu is a traditional Chinese liquor produced from grains through fermentation, distillation, aging and blending. The flavor of Baijiu is influenced by factors such as raw materials, starter, processes and the environment, and since the relationship between these factors and the flavor of Baijiu is still being analyzed, the identification of different Baijiu is still somewhat difficult. In this paper, the volatile differential markers of 42 types of strong-aroma Baijiu of different origin, alcohol content and grade were explored. A total of 24 volatile substances were detected by gas chromatography-electronic nose (GC-E-Nose) and 99 volatile substances were detected by gas chromatography-time-of-flight mass spectrometry (GC-TOF MS). The peak areas of the substances obtained by GC-E-Nose were analyzed by the partial least squares (PLS) method, and the substances with variable importance in projection (VIP) >1 were screened out. Combined with the qualitative results of GC-TOF MS, four substances (isobutyric acid, 2-butanone, 2,3-butanediol and 3-methylbutyric acid) were selected as volatile differential markers for strong-aroma Baijiu. An external standard curve was established to accurately quantify these four substances, and the Kruskal-Wallis test confirmed that the absolute contents of these four substances varied significantly among different samples (P < 0.01). Principal component analysis and hierarchical cluster analysis based on the absolute content of these four substances showed that different samples were prioritized for different alcohol contents. These four substances can be used as volatile differential markers of strong-aroma Baijiu samples. This research provides theoretical support for the detection and improvement of Baijiu product quality. © 2024 Society of Chemical Industry.