Influence of the olive variety and the zone of provenience on selenium content determined by cathodic stripping potentiometry (CSP) in virgin olive oils

The purpose of this paper was to determine the content of selenium in 50 samples of Sicilian virgin olive oils produced in six olive-growing zones from 10 different varieties of olives, and to investigate the possible connection between the olives varieties (cultivar), the zone of provenience and the selenium content in the oils. Cathodic stripping potentiometric analysis was used as a rapid, sensitive and reproducible method to determine selenium levels in acid extracts of olive oils. A precision of 2.8%, expressed as relative standard deviation of the measurements, and a detection limit of 0.6 μg kg−1 were obtained. The content of selenium found in the studied Sicilian virgin olive oils, ranged from 3.0 to 122.9 μg kg−1. The obtained results evidenced that olive oil samples from the same cultivar had a similar content of selenium, whereas some differences among the cultivars from the six studied zones were observed. These data provided evidence that both genetic factors (cultivar) and geographic factors (olive-growing zone), may influence the content of selenium in the studied Sicilian olive oils.