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.
Castillo-Luna et al. (Mon,) studied this question.