Determination of the oxidative stability of olive oil, using focused-microwave energy to accelerate the oxidation process.

Abstract

A new method is proposed for rapid monitoring of the oxidative stability of virgin olive oil. Samples were irradiated with microwave energy to accelerate the oxidation process and photometric monitoring was performed at 232 and 270 nm. Conditions such as microwave irradiation power, number of irradiation cycles, and irradiation time were optimized by means of multivariate screening that showed that irradiation power is the most significant condition in the oil oxidation process. Twelve samples of extra virgin olive oil of different oxidative stability--between 19 and 130 h calculated from the induction time of the Rancimat method, usual for analysis of olive oil in routine laboratories--were analyzed by the proposed microwave-assisted method, and a decrease in the induction time between 60 and 68% was obtained. The results obtained showed that correlation between the proposed method and the Rancimat method was excellent. The correlation coefficients were 0.9953 and 0.9963 for monitoring at 232 and 270 nm, respectively.