| Summary: | The physicochemical quality parameters, the total phenols contents and the oxidative stabilities at 120 to 160 ºC of commercial extra-virgin olive oils were assessed, allowing to confirm the quality grade as well as to group them according to the total phenols contents as low (88±7 mg CAE/kg), medium (112±6 mg CAE/kg) and high (144±4 mg CAE/kg) phenols levels. The results pointed out that oils with higher total phenols contents were more thermally stable. Kinetic and thermodynamic parameters were determined using the activated complex/transition-state theory, showing that their values did not significantly differ for the two highest total phenols contents, suggesting a hypothetically threshold saturation of the beneficial effect. High total phenols content would imply a significant more negative temperature coefficient, higher temperature acceleration factor, greater activation energy and frequency factor, higher positive enthalpy of activation, lower negative entropy of activation and greater positive Gibbs free energy of activation. The results confirmed that the lipid oxidation was a non-spontaneous, endothermic and endergonic process with activated formed complexes structurally more ordered than the reactants. A negative deviation from the Arrhenius behavior was observed for all oils being the super-Arrhenius behavior more marked for oils with lower total phenols contents.
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