Detection of sunflower oil in extra virgin olive oil by fast differential scanning calorimetry

Extra virgin olive oil (EVOO) is an economically valuable product, due to its high quality and premium price. Therefore it is vulnerable for adulteration by means of the addition of cheaper vegetable oils. Differential scanning calorimetry (DSC) has been suggested as a fast technique for the detection of adulteration. However, measurements still take several hours. Fast DSC measurements take several minutes. Therefore this study investigates the applicability of fast DSC for the detection of sunflower oil (SFO) in EVOO. Nine EVOOs, five SFOs and three mixtures were analysed. Cooling curves of EVOO and SFO show one major exothermic peak. Because the cooling curves of EVOO and SFO are very similar they cannot be used for the detection of adulteration. Heating curves of EVOOs show two major endothermic peaks after slow cooling (-2 degrees C/s), heating curves of SFOs only one. Addition of SFO to EVOO caused a rapid decrease in the coldest endothermic peak and can therefore be used in the detection of adulteration of EVOO by SFO. Depending on the type of olive oil, the presence of 2-10% SFO can already be detected. (C) 2014 Elsevier B.V. All rights reserved.