Effect of variable water irrigation supply in olive (Olea europaea L.) cv. Arbequina in Aragon (Spain).: II.: Extra virgin oil quality parameters

This study discusses the effects of different irrigation treatments in the extra virgin olive oil quality parameters. The olive oil samples were extracted from fruit samples collected in an olive orchard cv. Arbequina of Aragon (Spain) with the Abencor method. A full description of the field irrigation experiment in the olive orchard is presented in a companion paper in these proceedings. Olive oil quality parameters such as acidity value, oxidative stability, polyphenols, peroxides, fatty acid composition and sterol composition were performed in the laboratory. Results of the 1998 season indicated that the irrigation treatments had a significant effect in the oxidative stability, polyphenols and the composition of fatty acids. The oxidative stability and polyphenols were significantly higher in the non-irrigated treatment (T1) than in the most irrigated treatment (T4). Oleic acid content of treatment T1 was significantly smaller than the irrigated treatments (T2, T3 and T4). The average values of the quality parameters of the Arbequina extra virgin olive oil that were not affected by the irrigation I treatments were: acidity value 0.124 % in oleic acid, peroxides 5.16 meq O-2 Kg(-1) of fat and total sterols 1295 mg Kg(-1) with the following composition: campesterol 3.66%, stigmasterol 0.67%, global beta-sitosterol 95.0%, Delta-7 stigmastenol 0.13% and Delta-7avenasterol 0.28%.