Phenolic composition of extra virgin olive oil samples from Istria (Croatia)

Croatia is a Mediterranean country with a widespread production of olive oil in three different regions: Istria, Kvarner and Dalmatia. Each region has specific olive cultivars and different traditions in olive oil production. The objective of this study was to characterise Istrian olive oils obtained from local cultivars based on their bioactive components. Therefore, for the first time, we determined specific phenolic compounds in Istrian olive oils by using liquid chromatography coupled to triple the quadrupole mass spectrometer (LC-QQQ) and the antioxidant activity by DPPH assay. Results revealed that secoiridoid derivatives are the most represented phenolic compounds in Istrian olive oils. Among them, 3,4-DHPEA-EA was presented at the highest concentrations, ranging from 13.15 +/- 1.30 to 132.42 +/- 1.49 mg/kg. In all samples, a high content was also found for p-HPEA-EA and 3,4 -DHPEA-EDA with concentrations ranging from 4.82 +/- 0.33 to 68.69 +/- 15.89 mg/kg and from 2.93 +/- 0.11 to 28.11 +/- 1.41 mg/kg, respectively. Additionally, the antioxidant capacity was reported in the range from 0.66 +/- 0.05 to 4.12 +/- 0.06 mmol TE/kg. Principal component analysis (PCA) on obtained results indicated that oleuropein aglycon derivatives are the most important phenols for the antioxidant activity of lstrian olive oils.