Accelerated oxidation method and simple kinetic model for predicting thermooxidative stability of edible oils under storage conditions

Abstract

A kinetic model for predicting thermooxidative stability of fats under storage conditions is developed and parametrized using induction periods (IPs) measured at different temperatures and oxygen pressures using the Oxitest method. The model does not rely on a degradation mechanism, nor it requires determination of degradation products. Berthelot–Hood function was chosen for modeling the temperature dependence as it provides more realistic estimates compared to the Arrhenius equation. The geometry of the sample is taken into account via surface-to-volume ratio. For a commercially available sunflower oil, the estimated temperature coefficient of the Berthelot–Hood function was 0.0915 K−1 and the apparent reaction order with respect to oxygen was 0.155. Using these values, the estimated IP at 25 °C in air and surface-to-volume ratio 35 m−1 is 521 days with an uncertainty of 180 days. This is comparable to 460–490 days measured by Martín-Polvillo, et al. (2004) for an oil with similar composition using a long-term storage experiment. Despite only requiring a fraction of time, the model yields induction periods close to those from experiments at ambient conditions.