Influence of Various Irrigation Water Types On the Chemical Composition of Olive Fruit (Koroneiki Var.), As Well as The Physicochemical, Organoleptic Characteristics and Overall Quality Index of Its Virgin Olive Oil

Abstract

This investigation was carried out to study the influence of different irrigation water types on chemical composition and NPK elements of olive fruits taken from olive trees Kroneiki var as well as the chemical properties of the oil extracted from the olive fruit. The water types used include sweet water (SW), rain water (RW), ground water (GW) and agricultural draining water with sweet water (ADW:
SW.1:1). The extracted oils have been tested for their physiochemical properties, fatty acids composition, bioactive components, sensory attributes, overall quality index (OQI) and their contents of some minerals. The results showed that; olives irrigated by RW gave the highest oil percent (19.73 %) and lowest moisture content (48.58%) and crude protein (1.75 %). On the reverse, olives irrigated
by ADW+SW gave the lowest oil content (15.01 %) and highest moisture content (62.48%) and total carbohydrates (14.38%). Regarding the quality of the oil extracted from olive fruit, it has been found that the oil extracted from olives irrigated by GW and ADW +SW were of better oxidative stability and lowest oleic acid content. On the other hand, oil extracted from olive fruits irrigated by SW had lower
values of (%) acidity, k232 and K270 nm., ΔK, carotenoid and chlorophyll contents and higher content of total phenols and tocopherols. The results had shown also that oil extracted from olive fruits irrigated with RW were of higher acidity and peroxide values, carotenoids and chlorophyll contents compared to other oils extracted from olives irrigated with other irrigation water types. In addition, olives irrigated by RW gave oil having the best sensory evaluation (fruity 7.2) followed by GW (fruity 6.5) then SW (fruity 5.35) and ADW+SW (fruity 4.00). The absence of any negative attributes for all oil samples studied indicated that they all can be classified as extra virgin olive oil .Oil extracted from olive fruits irrigated by SW gave the highest value from OQI 8.55 followed by RW 8.44 then GW 6.37 and
ADW+SW 4.74. The results have shown also that the oil which has been extracted from olive fruits irrigated by RW has the maximum values of Pb, Ca, Fe, and Na metals being 1.96, 0.84, 1.66 and 0.81 mg/g olive oil respectively .