Characterization of the Geographical Origin of the Traditional Chinese Fermented Soybean Douchi by Gas Chromatography-Mass Spectrometry (GC-MS) and Chemometrics

Douchi is a highly appreciated product due to its unique flavor, high nutritional value, and health benefits. Douchi from different regions exhibits distinct characteristics. The objective of this study was to investigate the volatile profiles in douchi produced from different geographical origins using gas chromatography-mass spectrometry (GC-MS) and chemometrics. The volatiles were extracted by headspace solid-phase micro-extraction (HS-SPME) and subsequently determined by GC-MS. A comparative analysis was further conducted to identify the variations in volatile compounds among the samples. The correlation between the samples was investigated by employing cluster analysis (CA) and principal component analysis (PCA). An orthogonal partial least squares-discriminant analysis (OPLS-DA) model was established to discriminate samples from different regions and identify key differential compounds. A total of 46 volatile compounds were detected, among which terpenes, alcohols were the main compounds. Furthermore, 14 key differentiating compounds were screened out based on the OPLS-DA modle. The application of GC-MS combined with chemometrics offers a theoretical framework for douchi quality control and classification.