Author(s): Amira Yahyaoui, Ghayth Rigane, and Ridha Ben Salem
In this work the effect of different microwave heating times, that simulate the usual times used to cooking, on Tunisian olive oils was investigated. Traditional parameters, including free acidity, peroxide value, ultraviolet absorbance values at 232 and 270 nm, phenolic, chlorophyll and carotenoid compositions, were determined in four extra-virgin olive oil samples before and after microwave treatment. The results showed that heating by microwave apparatus produce losses in the quality of the different analyzed olive oils. The heating time did not promote the occurrence of hydrolysis in the samples since no changes in free acidity values were found. All other parameters were affected by exposure time in a similar way: in the first 3 min no marked changes were observed, after that the quality of the oil decrease significantly. Globally, the microwave heating time also affects the total chlorophylls, carotenoids and phenolic contents which clearly decreased as long as the exposure time increases. The use of extra-virgin olive oil may be encouraged especially at short microwave treatment times for both domestic and food catering applications.
