Kinetic modelling of the degradation of the α-tocopherol in biodiesel-rape methyl ester

The aim of this work was to study the influence of three major factors (light, atmospheric oxygen, temperature) responsible for the degradation of tocopherols. The evolution of α-tocopherol contents was analysed by high-performance liquid chromatography. Taguchi’s experimental design was applied to establish a mathematical model of α-tocopherols degradation in function of the studied parameters especially in a domain of temperature between 50 °C and 150 °C. The results show that the major factor is the temperature, especially above 100 °C. Light is a negligible factor, meaning that degradation is mainly due to an autoxidation phenomenon. Moreover, only interactions between temperature and atmospheric oxygen have been observed especially above 100 °C. The mathematical model was validated for a temperature of 75 °C and permits to calculate a predictive speed of degradation in this domain.