Differential scanning calorimeter application to the detectionof refined hazelnut oil in extra virgin olive oil

Abstract

The potential application of differential scanning calorimetry (DSC) to verify adulteration of extra virgin olive oil with refined hazelnut oil was evaluated. Extra virgin olive oil and hazelnut oil were characterised by significantly different cooling and heating DSC thermal profiles. Addition of hazelnut oil significantly enhanced crystallisation enthalpy (at hazelnut oil ⩾20%) and shifted the transition towards lower temperatures (at hazelnut oil ⩾5%). Lineshape of heating thermograms of extra virgin olive oil was significantly altered by hazelnut oil addition: a characteristic exothermic event originated at −27°C in extra virgin olive oil and progressively disappeared with increasing hazelnut oil content, while the major endothermic peak at −3.5°C broadened (at hazelnut oil ⩾40%) and the minor endothermic peak at 8°C shifted toward lower temperatures (at hazelnut oil ⩾5%). The preliminary results presented in this study suggest that DSC analysis may be a useful tool for detecting adulteration of extra virgin olive oil with refined hazelnut oil.