*2.2. Chemical and Physical-Chemical Analyses of Oil*

The so-called quality parameters (free acidity, peroxide value, *K*232, *K*270, and Δ*K* extinction coefficients), which are taken into account to establish the olive oil categories within the European Union according to the Commission Regulation 2568/91 [16] and subsequent amendments, were determined [16].

The total polar phenol content was determined using the Folin-Ciocalteau colorimetric method [17]. The results were expressed as caffeic acid equivalent in mg·kg−<sup>1</sup> oil.

The oxidative stability index (induction time expressed in hours) was determined by using an eight-channel 743 Rancimat instrument (Metrohm, Herisau, Switzerland), heating the oil samples (2.5 g) at 100 ◦C under an air flow of 10 L h−<sup>1</sup> [18].
