Composition, quality and oxidative stability of virgin olive oils from some selected wild olives (Olea europaea L. subsp. Oleaster)

Abstract

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 compiles with commercial standards, as well as for their appreciable amounts of tocopherols and phenolic compounds. Tocopherol analysis by HPLC revealed the presence of a, 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, a tocopherol is the most prominent, whereas β, γ and δ tocopherols are less represented. Results showed a clear influence of total phenols and o-dlphenols 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).