Characterization of empty cup aroma in Soy sauce aroma type Baijiu by vacuum assisted sorbent extraction

The empty cup aroma is a typical feature of soy sauce aroma type baijiu (SSB). Herein, a novel method based on vacuum-assisted sorbent extraction (VASE) combined with gas chromatography–mass spectrometry (GC–MS) was established for research on volatile compounds in empty cup of SSB. A total of 81 compounds were identified in the empty cup aroma of 8 SSB samples, involving 27 common compounds, and lactic acid was found to have the highest content. High-performance liquid chromatography (HPLC) combined with a chiral column was used to accurately conduct quantitative analysis of L-lactic acid and D-lactic acid, and it was found that the contents of D-lactic acid in all of the 8 SSB empty cup were higher than L-lactic acid. A total of 8 different SSB samples could be distinguished by principal component analysis (PCA) and heatmap analysis, and 7 compounds including L-lactic acid, D-lactic acid, ethyl hexadecanoate, benzeneacetic acid, acetic acid, 1,2-propanediol, hexanoic acid were selected as potential markers of empty cup aroma due to their high variable importance in projection (VIP) values (VIP >1.0). •Vacuum-assisted sorbent extraction for empty cup aroma was established.•L/D-lactic acid was quantified in empty cup of Soy sauce aroma type Baijiu.•Potential markers of empty cup aroma were determined by statistical analysis.