Oleaster (Olea europaea var. sylvestris), or the wild olive tree, has great interest as a source of genetic material for olive breeding programs. Nevertheless, information about its oil composition is scarce. In the present work, the characterization of oleaster fruit morphology and oil chemical composition from three different tree populations in Northeastern Portugal (Moncorvo, Alijó and Vila Nova de Foz Côa) was performed. The three studied populations presented some morphological differences in the fruits, but similar oil chemical composition. Oleic acid (68.9-70.6%) was the most abundant fatty acid. High variability was observed in total tocopherol content, ranging between 263 and 503 mg/kg. Additionally, high amounts of total sterols were found, from 1742 to 2198 mg/kg of oil. A rich composition in phenols was found with 14 phenolic compounds identified. The evaluated parameters for oleander oils allowed discriminating the oils according to the geographical origin and were consistent with those commonly found in olive oil, showing that they are particularly rich in antioxidants and can be exploited in breeding programs to increase the amounts of bioactive compounds in cultivated oils.
