Modelling the temperature dependence of oxidation rate in water-in-oil emulsions stored at sub-zero temperatures

The aim of the present research was to model the temperature dependence of lipid oxidation rate in water-in-oil emulsions stored at sub-zero temperatures. In fact, the application of the well-known Arrhenius equation resulted precluded in such conditions. To this purpose, the physical state and the oxidation rate of sunflower oil-water emulsions were evaluated from -30 to 60 degrees C. Results indicate that the rate of oxidation could be considered as a resultant of a complex interplay between the physicochemical changes occurring in the hydrophilic and hydrophobic phases as a consequence of phase transitions. By taking into account the changes in oil viscosity and in the reactant concentration in both lipid and water phase it was possible to set up a mathematical model able to describe the temperature dependence of oxidation rate in multiphase systems in the entire range of temperatures considered. (c) 2006 Elsevier Ltd. All rights reserved.