Determination of deficit irrigation treatments on olive fruit quality and olive oil (Memecik cv.) chemical composition and antioxidant properties

In this research, the influences of irrigation treatments (K1, K2, K3, K4, K5) on chemical properties, antioxidant compounds and activities of table olive and olive oils (Memecik) were investigated during three crop seasons (2012/13, 2013/14 and 2014/15). The three least irrigated (K3, K4 and K5) and non -irrigated (K1) regimes indicated that higher content of polyphenols of olive fruits were those with the most irrigated regime (K2). According to L", a* and b", results of statistical differences were determined between the treatments of K1 and K5 (P<0.05). There was no significant effect determined between irrigation treatments of the Memecik olive oil main fatty acids such as palmitic (C16:0), oleic (C18:1) and linoleic (C18:2) acid, except palmitic acid (first year) and linoleic acid (second year). When we look at the triacylglycerol (TAG) composition in the 2012/13 and 2013/14 crop seasons important statistical differences were determined between the irrigation treatments on some TAG contents (P<0.05) however these differences between irrigation treatments, although statistically significant, are very slight. During the last crop season, no significant effects were determined in the TAG composition between irrigation treatments. During the first and the second year, important statistical differences were observed between the irrigation treatments both for the total phenol content and bitterness index (K225) value of oils (P<0.05). The research showed that the K225 value of Memecik olive oils is above 0.360 value. Important differences were determined between the irrigation treatments on the alpha tocopherol content (P<0.05). DPPH' (2,2-diphenyl-1-picrylhy-drazyl) content (first and second year) and ABTS'+ (2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid) content (all crop seasons) were also significantly influenced by irrigation treatments due to changes in antioxidant compounds (P<0.05). Whereas all these differences, although statistically important, are very slight. In the light of the findings of this research, it was concluded that the use of the restricted irrigation regimes enabled water to be saved with very slight change in fruit and oil quality.