Assessment of Oxidative Stability in Palm Oil, Sunflower Oil, and Corn Oil under Different Temperature

The oxidation stability of edible oils decreases when exposed to high temperatures. This is an area of interest due to related health concerns it presents and food security. The study used kinetic and thermodynamics to assess the oxidative stability of palm, sunflower, and corn oil when exposed to frying temperatures of 180 °C and 200 °C. Rancimat and quality parameters were used to evaluate both oxidative stability and temperature influence on the oil. The Arrhenius equation and complex activated theory reaction calculated activation energy, rate constant, activation enthalpy, and entropy. From the results, the activation energy for palm ranges (from 90.8 to 100) Kj/mol; for corn (80.6 to 83.9) Kj/mol; and for sunflower oil (77.1 to 82.4) Kj/mol, depending on the frying cycles. This indicates that palm oil is comparatively the most resistant to thermal-oxidative stress since it requires the most energy for the oxidative reaction, followed by corn oil and sunflower. Thermodynamic parameters further supported this; the activation enthalpy for palm oil was (94.2 to 103.4) Kj/mol, corn oil (83.8 to 87.1) Kj/mol, and sunflower (80.3 to 85.6) Kj/mol. The reaction was found to be endothermic since the Gibbs free energies were all positive. The entropy values were all negative, indicating that the reaction favours the formation of the products more. The study observed that the rancidity rate is inversely proportional to activation energy and directly proportional to temperature and unsaturation of oils.