INFLUENCE OF IRRIGATION WITH MODERATE SALINE WATER ON "CHEMLALI" EXTRA VIRGIN OLIVE OIL COMPOSITION AND QUALITY

The main goal of this study was to investigate the effects of moderate saline water irrigation in the "Chemlali" olive cultivar grown in Sfax, an arid region of Tunisia, on the composition and quality of the resultant virgin olive oil in comparison to a control plot grown under rain-fed conditions. Free acidity, peroxide value, specific ultraviolet absorbance (K-232, K-270), fatty acid composition, induction time, total polyphenol and total chlorophyll contents were determined and reported. The irrigation did not affect free acidity and peroxide value. Whereas, specific ultraviolet absorbance (K-232, K-770), fatty acid composition, induction time, total polyphenol and total chlorophyll contents were affected by irrigation. Rain-fed virgin olive oils showed a statistically significant higher content of oleic and linoleic acids. Virgin olive oils extracted from moderate saline water irrigated trees had higher contents of palmitic, palmitoleic, stearic and linolenic acids and a longer shelf-life. A positive correlation was noted between polyphenol content and oxidative stability.