Kinetics of Peroxides Degradation to Hexenal During Bleaching of High Oleic Safflower Oil

Bleaching is an important step of the vegetal oil refining for the removal of impurities. Some of the reactions that take place during this stage can be explained by the catalytic properties of bleaching clays. The most important reaction is the decomposition of peroxides to secondary oxidation products, mainly trans-2-hexenal. Therefore, in the present study, empirical and mathematical models were applied to predict the kinetic parameters of peroxide reduction and the formation of trans-2-hexenal during bleaching of high oleic safflower oil. For this, neutralized high oleic safflower oil was mixed with bleaching clay (Tonsil Optimum 320 FF) at three different concentrations (0.5%, 1.0%, and 1.5% based on the weight of the oil), in a laboratory reactor with agitation at 90 °C, 100 °C, and 110±1 °C during 60 min. Results showed that the first-order mathematical model is suitable to predict both peroxide reduction and formation of trans-2-hexenal (R² > 0.90). Kinetics parameters of initial rate (k₀) and the decontamination constant (kd) suggest a high correlation between peroxide reduction to trans-2-hexenal and clays used for bleaching high oleic safflower oil. This information may be used to design particular bleaching conditions for high oleic safflower oil.