Phenolic Compounds, Antioxidant Activity, and Other Characteristics of Extra Virgin Olive Oils from Italian Autochthonous VarietiesTonda di Villacidro,Tonda di Cagliari,Semidana, andBosana

Abstract

Extra virgin olive oils (EVOOs) from the fruits of Italian autochthonous varieties Tonda di Villacidro, Tonda di Cagliari, Semidana, and Bosanawere investigated to promote their quality aspects. All the analyzed EVOOs showed low values of acidity (≤0.45%) and of peroxide value (≤6.22 mEq O ₂/kg). There were no relevant differences in fatty acids and triacylglycerols composition among the four EVOOs. Tocopherols determined by HPLC-FL revealed that Bosanaoil was characterized by the highest $\alpha$-tocopherol level (213.3 ± 55.4 mg/kg). Chlorophylls, carotenoids, and total phenol (TP) contents as well as antioxidant activity (FRAP, DPPH ^∙ , and ABTS ^∙+ assays) of the oils hydrophilic fractions (HFs) were assessed by spectrophotometric methods. Some differences concerning the antioxidant activity and the TP content were observed: Bosanaoil HF activity was the most pronounced (1.17 ± 0.37 mmol TEAC/kg) and it contained the highest TPs amount (335.20 ± 121.34 mg/kg). HFs phenolic composition was determined by HPLC-DAD. The main identified phenols were secoiridoids, dominating in Bosanaoil, such as decarboxymethyl ligstroside aglycone ( p-HPEA-EDA, 35.8 ± 19.9 mg/kg) and oleuropein aglycone (3,4-HPEA-EA up to 84.7 mg/kg). In summary, all the four varieties showed good characteristics for the use as quality EVOO.