Chemical properties and antioxidant activity of olive oils from selected autochtonous olive cultivars

Chemical characterisation was carried out on 22 virgin olive oil samples obtained from 5 autochtonous olive cultivars (Oblica, Lastovka, Levantinka, Drobnica, Mastrinka cvs.) from middle Dalmatia region. The olives that came from different groves in Croatia were all processed by centrifugation system in two phases. Several qualitative parameters were evaluated (free acidity, peroxide value and UV spectrophotometric indices) according to the official methods described in the EEC Regulation n. 2568/91 of the Commission of the European Union. The analyses of major (fatty acids) and minor components (phenolic fraction and their antioxidant power evaluated by ABTS● + and electrochemical test) was also carried out. Liquid– liquid extraction of phenolic compounds from olive oils was performed following the protocol described by Pirisi et al. (1), modified according to Rotondi et al. (2). Radical scavenging activity of phenolic extracts by ABTS + essay was performed according to Re et al. (3). An amperometric flow injection method (FIA) was used for the evaluation of the antioxidant power (AOP) of the phenolic extracts of the oil samples. The results for all samples have shown belonging to category of extra virgin olive oil, depending on analysed analytical parameters. Moreover, the oils had very good storage capacity, depending on fatty acid composition, and also very good phenols content. Particularly, among the most representative varieties, the tendency to higher antioxidant activity had oils produced from Lastovka variety, followed by oils from Oblica and Levantinka.