Application of Headspace Solid-Phase Microextraction and Multivariate Analysis for the Differentiation Between Edible Oils and Waste Cooking Oil

Waste cooking oil (WCO) can be recovered and processed into animal feed additives and bio-oils after purification. Unfortunately, edible oils (EOs) were adulterated with refining and purificating WCO, especially in China. Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) analysis has been applied for the determination of the characteristic volatile profile of pure EOs (sunflower oil, rapeseed oil, and olive oil), WCO, and their mixture. Coupling the HS-SPME/GC-MS analysis data with multivariate analysis (MVA) techniques, such as principal components analysis (PCA) and cluster analysis, it has been possible to classify EOs and WCO on the basis of different volatile compounds. Fresh EOs were characterized by a low number of volatile compounds, while WCO and its mixture are characterized by a prevalence of hexanal, (E)-2-heptenal, hexanoic acid, (E,E)-2,4-decadienal, p-allylanisole esdragol, dihydroanethole, anethole, eugenol, and curcumene. PCA showed similarities in clustering of the data obtained by GC-MS. MVA facilitates comparison of chromatographic profiles of volatile compounds characteristic for various EOs, WCO, and the different oil mixture for monitoring oil quality. MVA has been successfully applied to the analysis of adulterated EOs by the addition of cheaper WCO.