Importance of oleacin and oleocanthal on the oxidative stability of extra virgin olive oil measured by Rancimat

The influence of oleacin and oleocanthal concentration on thermal oxidative stability of extra virgin olive oil was investigated. A sample of fifty-six oils in their native state (native oil) and cleaned from phenols through a liquid-liquid extraction (dephenolised oil) was oxidised by Rancimat at 130 degrees C. Extension of induction period (E-IP), calculated as the difference between the induction periods of the native and dephenolised oils, was used as key parameter.This was correlated (Pearson's correlation test) with the primary quality indicators (free acidity and peroxide value), fatty acid composition, total phenols, oleacin and oleocanthal concentration, and the sum of these two last compounds (EDAs). Influence of free acidity and fatty acid composition on E-IP was low, while a significant and positive correlation with total phenols, oleacin and EDAs was found. However, no supplementary effect on E-IP was obtained at a concentration of EDAs up to 341 mg kg OE (oleuropein equivalent). Finally, a weak correlation was observed between total phenols and oleacin (r = 0.401), oleocanthal (r = 0.417) and their sum (r = 0.463) suggesting that these phenols should be considered as an independent quality indicator for extra virgin olive oil.