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The olive oil content in phenolic compounds depends on the variety of the fruit used for its extraction as well as on the predominant climate conditions in the tree cultivation area. Here, we report on the characterization of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivars Chemlali and Chétoui, grown in three different Tunisian locations, Zaghouan (North), Sousse (Center) and Sfax (South). Chétoui olive oil samples obtained from fruits of olive trees cultivated in Zaghouan and Chemlali olive oil samples obtained from fruits of olive trees cultivated in Sousse were found to have a higher mean total phenol content (1004 and 330 mg/kg, respectively). Olive oil samples obtained from fruits of both cultivars had different phenolic profiles and a higher content in 3,4‐DHPEA‐EDA when the olive trees were cultivated in Zaghouan. Both olive cultivars were found to have different responses to environmental conditions. Chétoui olive oil showed decreased oxidative stability when the fruits were obtained from olive trees cultivated in the center of Tunisia (34.8 h) and in Sfax (16.17 h). Furthermore, statistical data showed that the phenolic composition and oxidative stability of Chétoui olive oil varied more by location than those of Chemlali olive oils.

SUMMARYComposition, quality and oxidative stability of virgin olive oils from some selected wild olives (Olea europaea L. subsp. Oleaster).A study on the characterization of virgin olive oils from wild olives (Olea europaea L. subsp. Oleaster) was conducted in order to define new cultivars which are welladapted to the Tunisian environment and yield high quality oils. The study was done during the crop years 2003/04, 2004/05 and 2005/06. The main analytical parameters of the oils were evaluated: fatty acid compositions, chlorophylls, carotenoids, tocopherols and phenolic compounds as well as their relationship with oxidative stability.The fatty acid composition of all the wild olive trees tested produced virgin olive oil which complies with commercial standards, as well as for their appreciable amounts of tocopherols and phenolic compounds. Tocopherol analysis by HPLC revealed the presence of α, β, γ and δ tocopherols in all the studied olive oils. Total tocopherol content was significantly influenced by the varietal factor. It ranged from 310 (SB12) to 780 mg/kg (H3). As for total tocopherols, the amount of each tocopherol varied according to genotype. α tocopherol is the most prominent, whereas β, γ and δ tocopherols are less represented. Results showed a clear influence of total phenols and o-diphenols on virgin olive oil stability (R = 0.905, 0.963 P < 10 -3 , respectively), and a much lower contribution of tocopherols (R = 0.568) and acidic composition (R = 0,563). KEY-WORDS:Oxidative stability -Phenols -Tocopherols -Virgin olive oil -Wild olive. INTRODUCTIONThe olive tree (Olea europaea L.) is a subtropical species typical of the Mediterranean basin where it represents the most important oilproducing crop. Virgin olive oil, due to its use without refining, shows very interesting nutritional and sensorial properties, being one of the pillars of the so-called Mediterranean diet. Its oxidative stability, sensory quality and health properties stem from a prominent and well-balanced chemical composition (Boskou, 1996;Servilli et al., 2004).The increasing popularity of olive oil has been mainly attributed to its high content of oleic acid, which may affect the plasma lipid/lipoprotein profiles and its richness in phenolic compounds acting as natural antioxidants, which may contribute to the prevention of human disease (Visioli et al., 1998;Visioli et al., 2000).Tunisia occupies the fourth place on a worldwide scale in terms of olive oil production (IOOC, 2004). Tunisian olive plantations are spread all over the country in different edapho-climatic conditions and account for about 63 million trees covering 1.6 million hectares. A major effort has been made recently for improving the quality of olive oil produced in Tunisia.At present the Tunisian olive grove is dominated by only two main varieties: Chétoui and Chémlali. The introduction of different virgin olive oil types into the market, with different sensory and chemical Composition, quality and oxidative stability of virgin olive oils from some selected wild ...