Assessment of the thermo-oxidation of three cucurbit seed oils by differential scanning calorimetry

Abstract

Differential scanning calorimetry (DSC) technique was used to assess the thermo-oxidation of oils of three cucurbit species named Cucumis melo, Citulus lanatus and Cucumeropsis mannii. The DSC oxidation was conducted under isothermal conditions at four different temperatures: 110, 120, 130 and 140 °C. Thermal oxidation by DSC performed in the presence of oxygen (50 ml/min) revealed three step oxidation of cucurbit seed oils. Oxidation temperature is high for C. lanatus oil (130 °C) compared with C. melo oil (125.1 °C) and C. mannii oil (121.0 °C). C. lanatus oil exhibited high value of oxidative induction time (T0) at all isothermal temperatures and was consequently more thermo-stable than C. melo oil and C. mannii oil. The analyzed cucurbit oils were more stable than some edible oils (corn and sunflower oils) in comparison with their oxidative induction time. There was a good correlation (R² ≥ 0.91) between oxidative induction time and isothermal temperatures which revealed that oxidative stability of oils can be accurately determined in short time by DSC.