Kinetic adsorption of pigments peroxides and tocopherols during the bleaching process of soybean oil

Abstract

Bleaching is an important process of refining and removes impurities from edible oils. During this process, suspended materials are adsorbed at different adsorption rates, on clay particles. These adsorption rates are important to the design of the process. For this reason, both empirical and theoretical mathematical models were applied in this work in order to predict the adsorption kinetic parameters for tocopherols, peroxides and pigments. The experimental part consisted of mixing neutralized soybean oil with different concentrations of bleaching clays (0.16, 1.0 and 2.0 % w/w) in a laboratory reactor at 96 °C for a 64 min period. Results showed that the theoretical model of first order made better predictions (R² >0.93) than the empirical models of the kinetic adsorption for tocopherols, peroxides and pigments. The determined kinetic parameters suggest that these bleaching clays presented a high capacity for pigment and peroxide adsorption. The tocopherols were lost as the bleaching clay dosage was increased.