Storage of extra virgin olive oil and its effect on the biological activity and concentration of oleocanthal

The olive oil phenolic, oleocanthal has recently received attention regarding its anti-inflammatory capacity and the thought that it is partially responsible for the beneficial health effects of the Mediterranean diet. Extra virgin olive oil (EVOO) containing oleocanthal is often consumed after storage for a substantial amount of time and for oleocanthal to indeed provide health benefits, it has to be present in a substantial quantity throughout the shelf-life of EVOO. Therefore, the aim of the current study was to investigate if natural light and/or oxygen (O2) exposure (via atmospheric air) combined with extended storage, as would occur on a common domestic basis, affected the concentration of oleocanthal in EVOO. One EVOO containing 90 mg/kg oleocanthal was stored for 10 months with and without exposure to light and or O2. Oleocanthal concentrations were quantified using high performance liquid chromatography-mass spectrometry (HPLC-MS) and its biological activity determined with a taste bioassay measuring the intensity of oropharyngeal irritation. A significant difference in oleocanthal concentration was observed amongst the different storage treatments (p = 0.05). Oleocanthal concentration degraded to a maximum of 37% (90 ± 13 mg/kg to 56 ± 9 mg/kg) after 10 months exposure to both light and O2. Limiting light and O2 over 10 months resulted in a 15% decrease in oleocanthal (90 ± 13 mg/kg to 76 ± 9 mg/kg). Oleocanthal biological activity mirrored the results of oleocanthal concentration (r = 0.8, p < 0.05). Overall, the findings support the role of oleocanthal as a potential health promoting compound in EVOO as significant concentrations remain in EVOO after exposure to light, oxygen and over time.