Ultrahigh-Performance Liquid Chromatography–Tandem Mass Spectrometry-Based Untargeted Metabolomics to Differentiate Guizhou Glutinous Sorghum and Hongyingzi Sorghum

The limited data on the systematic evaluation and composition of metabolic compounds in different sorghum varieties makes their distinction difficult. Here, we employed untargeted metabolomic and multivariate statistical analyses on 129 sorghum samples collected from various regions across China using ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). This approach enabled us to differentiate between two specific varieties of sorghum: Guizhou glutinous sorghum (GZGS), used in the production of soy sauce-flavoured baijiu in the Zunyi baijiu production area, and Guizhou Hongyingzi sorghum (GZ-HYZ), used in the production of Maotai-flavoured baijiu. The metabolic compounds in GZGS, mixed sorghum from other production areas, GZ-HYZ, and other glutinous sorghum varieties in Guizhou (GZ-others) were analysed, and key differential metabolites were identified. Differences were observed between the composition of GZ-HYZ and GZ-others. The phenylpropanoid biosynthesis pathway produced large amounts of flavonoids and lignins with antioxidant activity and phenols, which partially explained the formation of the Maotai liquor aroma. UPLC–MS/MS-based untargeted metabolomics can effectively reveal the differences in metabolites among sorghum varieties, thereby facilitating the authentication of GZGS and GZ-HYZ for brewing purposes.