The evaluation of the influence of olive oil phenols on the stability of extra virgin olive oils by the determination of the oxidative stability index, the ABTS•+ and DPPH• radical test, and the quali-quantitative analysis of the phenolic compounds, plays a key role in the assessment of the overall olive oil quality. In this study virgin olive oils from selected autochthonous Croatian varieties were investigated in order to evaluate the contribution of their phenolic compounds on the oxidative stability. Two year researches were conducted on the monovarietal olive oils (Oblica, Lastovka, Levantinka, Drobnica, Mastrinka) obtained by the same technological processing system, centrifugal extraction into two phases. The olive fruits came from different groves in Dalmatia region, a central part of Croatian Adriatic coast. The polar extracts of olive oil samples were submitted to spectrophotometric analysis of total phenols and to liquid chromatographic determination of their quali-quantitative profile (HPLC-DAD/MSD). To obtain a complete description of oil samples, fatty acid composition, ultraviolet indices (K232, K270 and ∆K), free acidity degree and peroxide value were also determined according to the European Union methods stated in Regulation 2568/91. Beside analyses mentioned above, researches were amplified by oxidative stability determination by Rancimat method, evaluation of antioxidant activity by DPPH and ABTS methods as well as antioxidant capacity (AOP). The evolution of the analytical parameters studied showed that certain groups of phenolic compounds (secoiridoides, flavones and lignans) have a higher antioxidant activity and antioxidant capacity than the total phenols. The results obtained in this study will contribute to better understanding of peculiar characteristics of local varieties of olive oil set the basis for their characterization and evaluation.
Online ISSN: 1459-0263Year: 2013, Vol. 11, Issue 1, pages 126-131Publisher: WFL.
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