Characterization of Volatile Organic Compounds of Giant Salamander (Andrias davidianus) Oil Adulterated with Different Amounts of Peanut Oil by Gas Chromatography-Ion Mobility Spectrometry Combined with Chemometrics

The volatile components in giant salamander oil adulterated with different amounts of peanut oil (0%, 5%, 10%, 20%, 30%, and 100%) were studied by gas chromatography-ion mobility spectroscopy (GC-IMS) combined with chemometrics. The results showed that a total of 41 volatile compounds were identified in all samples, including 21 aldehydes, 6 ketones, 4 alcohols, 4 heterocyclic compounds, 3 esters, 2 sulfur-containing compounds and 1 acid. With increasing adulteration level, the contents of aldehydes, heterocycles, acids and esters increased, while the contents of ketones, alcohols and sulfur compounds decreased. A partial least squares regression (PLSR) model between volatile components and adulteration level was established. The correlation coefficient (R²) values for the calibration and verification sets were 0.9924 and 0.9882, respectively, indicating that the reliability of the model. Principal component analysis (PCA) showed that the cumulative contribution rate of the first two principal components (PC) was 94.3%, indicating that the different adulteration levels could be well distinguished by volatile components. Thirteen differential volatile compounds with variable importance for the projection (VIP) scores greater than one, including seven aldehydes, three ketones, one alcohol, one sulfur compound and one ester, were selected by partial least squares-discriminant analysis (PLS-DA). PCA and cluster analysis showed that these differential volatile components could also be used to distinguish the different adulterated salamander oil samples. This study can provide technical support for the nondestructive rapid identification of adulterated giant salamander oil.