Effect of the Type of Water Used in Irrigation of Olive Trees on the Storability of Olive Oil at Room Temperature

This study covers the effect of irrigation of olive trees with water of different types (treated wastewater, well water and rain-fed) on the storability of the produced olive oil at room temperature (10-30°C). The results of the fatty acid profile revealed that the fresh olive oil samples contain about 16-18% palmatic, 2.3-2.4% stearic, 61-65% oleic, 14-17% linoleic and 0.7-0.9% linolenic acid. It was observed that water type had no significant effect on the quantity of both palmitic and stearic acids. On the contrary, water type affected significantly the quantity of oleic, linoleic and linolenic acids. Higher quantities of linoleic and linolenic and lower one of oleic acids were present in olive oils taken from rain-fed olive trees. It was evident that the type of water used in irrigation had a significant effect on the storability of olive oil where rain-fed olive trees produced olive oil that had the best storability i.e lower acidity, lower peroxide values, higher total phenol content, higher sensory scores for the positive sensory attributes with the absence of negative ones. Taking into consideration the type of package used in storage of olive oil at room temperature (10-30°C), the data obtained revealed that metal cans were the worst in preserving the olive oil quality parameters followed by plastic containers whereas glass containers gave the best results. Regarding the storage time (0, 3, 6 and 9 months), the results showed that more deterioration for the quality of olive oil was achieved after 6 months storage.