Evaluation of effeciancy of luteolin on stability of olive and canola oils in different temperatures according to the mechanism of inhibitory action

A kinetic analysis was performed to evaluate the antioxidant behaviour of luteolin in the triacylglycerols of olive (TGO) and canola (TGC) oils. The process was performed at high (kinetic regime) oxygen concentrations at at 60, 80, and 100 °C in the dark. Different kinetic parameters were determined, including the stabilization factor F, the oxidation rate ratio ORR, the antioxidant activity (A) and the mean rate of inhibitor consumption WInH. The oxidative stability measures of the bulk olive and canola oils dramatically improved by the antioxidant added. Luteolin due to its increased partitioning at water-oil interface exerted a highest activity at 60°C and a concentration of 0.02%. Also, the rate of olive triacylglycerols oxidation increased significantly with increasing luteolin concentration at the corresponding temperature. This behaviour was explained in terms of a more participation of antioxidant molecules and radicals in side reactions, i.e. 10 and 11 ( and , respectively). The rate constant of antioxidant consumption in side reaction(s) (Keff) and mean rate of initiation (Wi/f) values revealed that luteolin takes part in chain propagation and initiation reactions to a higher extent during TGC oxidation. Generally, the activity of luteolin increased and decreased, respectively, in TGO and TGC with rising temperature. This behavior was attributed to the change in the mechanism of inhibitory action with prevailing the reactions 7 ( , 8 ( ), and 9 ( ) for olive oil, and pro-oxidative side reactions to a higher degree in TGC.