Chemical and thermal characterization of Tunisian extra virgin olive oil from Chetoui and Chemlali cultivars and different geographical origin

Application of differential scanning calorimetry (DSC) to discriminate among extra virgin olive oils on the basis of cultivar-environment interaction was preliminary evaluated on Tunisian samples from two varieties (Chetoui and Chemlali) and different geographical origin relating thermal properties obtained by cooling and heating thermograms to chemical composition. Higher content of triunsaturated triacylglycerols and oleic acid and lower amount of palmitic acid were detected in Chetoui samples in comparison with Chemlali oils. Cooling thermograms exhibited two well distinguishable exothermic peaks in all samples; the major event at lowest temperature was taller and sharper in Chetoui samples whereas the other peaking at highest temperature was more evident for Chemlali oils. Crystallization enthalpy did not account for the differences observed in chemical composition between the two cultivars. On the contrary, T (on) and T (off) of crystallization were found to significantly differ according to the compositional differences due to cultivars and geographical provenience interaction. Heating profiles exhibited a minor exothermic peak followed by multiple endothermic events and appeared also distinctive of oil samples from two cultivars. All thermal properties obtained by the analysis of heating thermograms significantly differed among oil samples from different geographical provenience. The application of DSC appeared useful to differentiate samples of different cultivars and/or geographical proveniences.