17/12/08 The chemical composition and quality of virgin olive oil may be influenced by genotype and different agronomic and technological factors. A study tested the ideal ripening stage to extract an olive oil with proper chemical profiles and the best oxidation levels.

Extra virgin olive oil is considered to be the best olive oil for its organoleptic characteristics (its capacity to preserved its original properties, such as smell, taste, colour and texture), for its oxidative stability and its chemical composition. It is practically the only vegetable oil that can be consumed directly in its raw state and contains important nutritional elements (vitamins, antioxidants, etc.).

The results from the italotunisian study reveal that the chemical composition and quality of virgin olive oil may be influenced by genotype and different agronomic and technological factors. The study was carried out by members of the Laboratoire Caractérisation et Qualité de l’Huile d’Olive, Centre de Biotechnologie de Borj-Ce´dria, Tunisia, and the Dipartimento di Scienze degli Alimenti, Università di Bologna, Italy; the paper was published in 2008 in the journal Food Chemistry.

The oxidative stability, sensory quality and health properties of virgin olive oil stem from a prominent and well-balanced chemical composition. In fact, the high content of oleic acid in olive oil serves to slow down penetration of fatty acids into arterial walls.

The chemical composition of virgin olive oil may be influenced by genotype and different agronomic (i.e. fruit ripeness degree, water supply) and technological factors. This research reports the evaluation of the influence of the olive ripening stage on the quality indices, the major and the minor components and the oxidative stability of the two main monovarietal Tunisian cultivars (cvv. Chétoui and Chemlali) virgin olive oils. The oils sampled at five different ripeness stages were submitted to different analysis.

Moreover, the triacylglycerol and fatty acid compositions, and minor components, pigments and their relation with the oil oxidative stability were evaluated. The tested oils showed very good correlation between the oxidative stability and their composition.

The chemical data discussed in this work can be considered useful in providing information about the presence in the oil of major and minor compounds depending on olive ripening. The analytical parameters studied remained widely within estimated limits of the regulation throughout the maturity process. Nevertheless, this research evidenced that the oleic/linoleic acid ratio shows a decreasing trend as the olives ripened.

With regard to phenolic compounds, Chétoui had the highest stability value. Finally, the present work shows in Chétoui, the anticipate harvest-date, gave the best results in terms of all the parameters considered. Instead, for the cv. All that data could be used to define the ideal ripening degree to confer a good balance between chemical profiles.