Application of a modified Arrhenius equation for the evaluation of oxidation rate of sunflower oil at sub-zero temperatures

The application of the Arrhenius equation for the prediction of oxidative reaction rate in frozen foods is often precluded because of deviations from linearity. The latter are mainly caused by the occurrence of phase transitions of crystallizing components (that is, water, lipids, sugar). The aim of the present research was to study the temperature dependence of the lipid oxidation rate as affected by its physical state. To this purpose, the physical state and the oxidation rate of sunflower oil was evaluated from −30°C to 60°C. In this temperature range, sunflower oil presents different solid-liquid ratios because of the crystallization phenomena. A mathematical model accounting for both temperature and physical state was proposed to describe the kinetics of oxidation in the entire temperature range considered.