Regional Differentiation of Olive Oil of the Koroneiki Olive Cultivar from the Ionian Islands Based on Key Volatile Compounds and Descriptive Data Analysis

Given that olive oil produced in the Ionian islands has not been extensively studied, forty-seven olive oil samples of the Koroneiki olive cultivar were collected from Zakynthos, Kerkyra, Kefalonia, and Leukada, which comprise well-known islands of the Ionian Sea. The samples were subjected to analysis of volatile compounds using headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS). Based on HS-SPME/GC-MS analysis, twenty-five volatile compounds were tentatively identified and semi-quantified using the internal standard method. Volatile compounds included alcohols, aldehydes, benzene derivatives, esters, hydrocarbons, ketones, and terpenoids. The application of descriptive data analysis, such as multivariate analysis of variance (MANOVA), linear discriminant analysis (LDA), and factor analysis (FA), to the semi-quantitative data (μg/L) of the identified volatile compounds resulted in the extraction of key volatile compounds that differentiated olive oil samples of the Koroneiki olive cultivar according to geographical origin. The cross-validation method of LDA showed a prediction rate of 83.0%, whereas the variance explained by FA was approximately 69.06% (69.055%). The key volatile compounds that were associated most with the geographical origin of olive oil samples were (Z)-1,3-pentadiene, dodecane, 2,2,4,6,6-pentamethyl-heptane, 3-ethyl-1,5-octadiene, 2,4-dimethyl-heptane, 4-methyloctane, ethanol, 2-hexanol, and 3-methylbutanal, among others. The study contributes to the regional features of olive oil of the Koroneiki olive cultivar from the Ionian islands based on key volatile compounds and further supports the consecutive research of the international community regarding olive oil authentication.