Prediction refined vegetable oils oxidative stability using the accelerated thermal test: evidence from soybean, sunflower, palm and palm olein oils

Abstract

In this study, the physicochemical characteristics and oxidation kinetics of four refined oils—soybean, sunflower, palm, and palm olein—were evaluated. Such oils were assessed for their fatty acid profile (FAP), free fatty acids (FFA), p -anisidine value ( p -AV), peroxide value (PV), saponification value (SV) and iodine value (IV). Accelerated oxidation was performed using the Rancimat method at temperatures from 373 to 403 K at 10 K intervals. The oxidation kinetics were characterized by determining the rate constant (k), temperature coefficients (T coef ), activation energy (E a ), temperature acceleration factor (Q 10 ), and thermodynamic parameters, such as enthalpy (ΔH) and entropy (ΔS), in accordance with the Arrhenius model and the theory of activated complexes. Palm oil had greater resistance, as it needs more activation energy for the oxidation reaction. Based on the estimated shelf life at 298 K (25 °C), palm oil exhibited the greatest oxidative stability (6.93 years), offering a much longer shelf life than the other oils, followed by palm olein (3.71 years), soybean oil (2.26 years), and sunflower oil (1.07 years). These results revealed that rancidity is directly linked to temperature and oil unsaturation. • Sunflower and soybean oils are rich in unsaturated fatty acids (UFA). • Palm oil is most stable, with predicted shelf life of 6.93 years at 25 °C. • Oxidation reduces sunflower oil shelf life from 1.91 y at 20 °C to 0.35 y at 35 °C. • Kinetics confirm high thermal oxidation susceptibility of highly unsaturated oils. • Results help select oils for better industrial food processing and shelf life.