Evaluation of the oxidative stability and organoleptic properties of extra virgin olive oils in relation to olive ripening degree

The aim of this paper was the evaluation of the influence of the olive ripening degree on the oxidative stability of monovarietal extra-virgin olive oils, determined by OSI (Oxidative Stability Instrument) index and on the variation of their sensory score. Two cultivar of olives (cvv. Ghiaccolo e Nostrana di Brisighella, both from the Brisighella area) were picked at four different stages of ripeness and immediately processed by an experimental mill. In order to comprehend the relationship between olive ripening degree and oil's content of protective compounds, the oil samples were submitted to spectrophotometric analysis of polyhenols and o-diphenols and to liquid chromatographic determination of their quali-quantitative profile (HPLC-DAD/MSD). Moreover, it was evaluated the fatty acid composition (as oleic acid/linoleic acid ratio) and its relation with the oil oxidative stability. Finally, the samples were sensory analysed to establish the influence of the olive ripening degree on the oil quality. All the data were elaborated to emphasize eventual significant differences, due to the olive ripening degree.