Oxidation kinetics in olive oil triacylglycerols under accelerated shelf-life testing (25-75 °C)

A kinetic study of the autoxiclation reaction in olive oil triacylglycerols stored in darkness at different temperatures (25, 40, 50, 60 and 75 degreesC), in absence of pro- and antioxidant compounds to avoid confounding effects, is described. After the induction period (IP) the decrease in the oxidizing substrate and the formation of primary oxidation products followed a pseudo-zero-order kinetic, and the calculated Ea from the Arrhenius equation for the formation of hydroperoxides was 32.1 kJ (.) mol(-1). The formation of secondary oxidation products followed a pseudo-first-order kinetic whose rate reaction constant also increased exponentially with temperature. The first oxidation index to exceed the upper limit in the EU regulations was PV, followed by K-232 and K-270. The time required reaching these limits and the rancidity threshold showed a potential dependence on temperature, and therefore with accelerated storage at 75 degreesC, POO shelf-life in ambient conditions (25 degreesC) can be predicted. Finally, there was a good linear relationship between the time required to reach the rancidity threshold and the IP of the formation of the 2,4-decadienal, and hence this instrumental determination could be useful to measure sensory recognition of the rancid defect in POO.