Accelerated shelf life testing (ASLT) of oils by light and temperature exploitation

The peroxide formation rate was measured in sunflower and soybean oils exposed to increasing light intensity, from 0 to 8000 lx, at 10, 20 and 30 degrees C. Results indicated that shelf life estimation of photosensitive foods under actual or accelerated conditions cannot be correctly achieved if the effect of light is not taken into account. At each lighting level, the Arrhenius equation was applied to develop a model predicting oil shelf life. Thermal activation energy was lower than 50 kJ/mol, indicating temperature to be a scarcely efficient accelerating factor. In contrast, the oxidation rate was significantly affected by light according to a power law equation, whose parameters describe the electromagnetic activation energy of the reaction. The model accounting for the effect of light on oxidation rate was merged with the Arrhenius equation to get a model predicting shelf life on the basis of the concomitant changes in both temperature and light.