Analysis of Non-Volatile Compounds in Soy-Sauce Aroma and Flavor Type Raw Liquors Based on BSTFA Derivatization

Non-volatile compounds (NVCs) are important for the taste and mouthful of Baijiu, but few studies were carried out on NVCs up to now. The soy-sauce aroma and flavor type raw liquors (SSRLs) from 7 different rounds in the same production cycle were detected using N, O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization combined with GC-MS, and 80 kinds of NVCs were targetedly and precisely quantified. As the number of the rounds increased, the contents of long-chain fatty acids and disaccharides other than trehalose that derived from the raw materials in SSRLs decreased, while the content of furoic acid was the opposite. The contents of short and medium chain fatty acids, trehalose, monosaccharides, aromatic compounds, alcohols and alditols increased first and then decreased. Alditols reached their peak in the 3rd round SSRL, while the rest peaked in the 4th or the 5th round SSRL. 8 NVCs with high content and significant variation were screened by OPLS-DA, including 2,3-butanediol, palmitic acid, threonine, malic acid, glycerol, linoleic acid, 2-hydroxybutyric acid, and furoic acid. It was speculated that they were related to the presentation of sweetness and astringency in the different rounds of SSRLs. Pathway analysis suggested that the metabolisms of these NVCs were mainly concentrated in galactose, starch, and several amino acid metabolic pathways. The study clarified the composition and proportion of non-volatile compounds in sauce-flavor Baijiu, aiming to provide a theoretical reference for an in-depth understanding of its complex taste profile.