Composition of total sterols (4-desmethyl-sterols) in extravirgin olive oils obtained with different extraction technologies and their influence on the oil oxidative stability.

The composition and antioxidant activity of total sterols in extravirgin olive oils obtained with different extraction technologies from olives harvested at two ripening stages, were studied. The antioxidant activity was evaluated with an Oxidative Stability Instrument (OSI), by using a model system (made of a mixture of treated/untreated commercial refined peanut oil) enriched with the total sterol fractions of the extravirgin olive oils. No correlation was found between the OSI time and the extraction technologies, the ripening stages or the actual amount of sterols added. No significant differences were observed in the percent composition of sterols of extravirgin olive oils produced with different technologies during the same harvesting period. The latter, however, had a significant effect on the percentage of beta-sitosterol and 5-avenasterol in extravirgin olive oils produced with the same technology.