Effect of the phenol antioxidant type on the kinetics and mechanism of inhibited lipid oxidation in the presence of fatty alcohols

Abstract

AbstractA kinetic analysis of inhibited lipid autoxidation in the presence of a phenol antioxidant and a hydroxy compound is proposed. It is based on studies of the dependence of the WROH/Winh ratio (between the inhibited oxidation rates in presence and absence of a hydroxy compound) on the hydroxy compound concentration. This analysis permits establishing the mechanism of action of the hydroxy compound in the presence of different types of phenol antioxidants during inhibited lipid oxidation. The kinetic analysis has been applied to the oxidation at 80°C of triacylglycerols of sunflower oil (TGSO) inhibited by 0.1 mM hydroquinone, butylated hydroxytoluene (BHT) or α‐tocopherol in the presence of different concentrations of 1‐tetradecanol (1‐TD) and 1‐octadecanol (1‐OD). A linear character of this dependence is established during hydroquinone‐inhibited oxidation of triacylglycerols of sunflower oil in presence of 1‐TD. In the case of α‐tocopherol this dependence is linear for both 1‐TD and 1‐OD. The equilibrium constant of interaction between the phenol antioxidant and the fatty alcohols is determined by the angle coefficient of the linear dependence. The hydroquinone‐inhibited autoxidation of TGSO in the presence of 1‐OD has shown a non‐linear character of the dependence under consideration. A kinetic model describing simultaneous participation of 1‐OD in reaction with both the phenol antioxidant and the lipid hydroperoxides is deduced. Studying the kinetics of BHT‐inhibited autoxidation of TGSO in the presence of 1‐OD, it has been shown that due to steric reasons there is no interaction between 1‐OD and BHT, 1‐OD participating in the process only by accelerating the decomposition of the lipid hydroperoxides.