Chapter 6 - Influence of Irrigation Management and Ripening on Virgin Olive Oil Quality and Composition

Abstract

The olive tree is generally grown under rainfed conditions, especially in Castilla–La Mancha, a region with limited water resources. Nevertheless, since irrigation increases the yield of the olive orchard, even with a low amount of water, there is increasing interest in irrigated agriculture. This has led to a situation in which some of the traditional olive groves and the majority of the new ones are being adapted to irrigation techniques. However, a satisfactory compromise between the amount of water applied and the improvement in the production of the olive crop and characteristics of virgin olive oil must be reached. Some recent research has shown differences in the chemical makeup and sensory characteristics of virgin olive oil from irrigated and rainfed olive trees. The chemical components most influenced by irrigation are the phenolic compounds, which affect both the oxidative stability and the sensory characteristics, especially the bitterness attribute, showing in both cases an inverse relationship with the amount of water applied to the olive trees. This aspect is important in olive cultivars that produce virgin olive oils with high bitterness and pungency, like the Cornicabra variety in Castilla–La Mancha and therefore just the right level of irrigation could enhance its sensory characteristics. To optimize sustainable irrigation conditions in the Cornicabra olive cultivar grown in Castilla–La Mancha, a region where aquifers are over-exploited, and to study the effect of different irrigation management and ripening on the composition of Cornicabra virgin olive oil, different irrigation treatments (based on 100% crop evapotranspiration, ETc, also known as the FAO method, 125 FAO, two different regulated deficit irrigation strategies and rainfed) were applied to a traditional olive orchard (Cornicabra cv).