Alteration of the Phenolic Fraction of Extra Virgin Olive Oil Subjected to Frying Conditions

Deep-frying in extra-virgin olive oil (EVOO) is an appreciated culinary practice that confers unique organoleptic features to fried food. However, high temperature (above 180 °C) contributes to deteriorate the health benefits of EVOO by accelerating degradation reactions. In this research, we measured the concentration of main phenolic compounds contributing to the health claim included in the European Commission (EU) 432/2012 in EVOOs subjected to frying for 90 min at 180 °C. For this purpose, four monocultivar EVOOs (“Arbequina”, “Cornicabra”, “Hojiblanca”, and “Picual”) with different phenolic profile were selected to study the impact of frying on phenols. A significant decay in the phenolic content was observed for all EVOOs during frying. In addition, we detected changes in the phenolic profile by conversion of open forms of oleuropein and ligstroside aglycones (oleomissional and oleokoronal) to oleacein and oleocanthal in the first frying cycles.