Absolute Quantitation of Phenolic Compounds in Olive Oil for Health Claim Recognition

The European Regulation (UE) 432/2012 includes a specific health claim for olive-oil-associated with its phenolic content, which is based on its protective role against lipid oxidation in the blood. To make use of the health claim, olive oil must have a minimum concentration in phenolic compounds of 250 mg/kg. Reviewing the health claim, the phenolic compounds referred to are the secoiridoid derivatives of hydroxytyrosol and tyrosol. A method based on absolute quantification of phenolic compounds in olive oil is proposed for the recognition of the health claim. The method involves liquid-liquid extraction with a 1:8 (v/v) oil:extract ratio to avoid saturation of the extract in oils with a higher phenolic content and its subsequent determination through LC-MS/MS in multiple reaction monitoring (MRM) mode, the gold standard technique in many application fields because of its analytical features. The optimized method was applied to a set of 100 extra virgin olive oils (EVOOs), and the results obtained were compared with the classic Folin-Ciocalteu method. The comparison between the two methods showed that the classic method is a non-selective method that can be affected by many interferences and that the Folin method underestimates the real phenolic content.