Irrigation-induced salinity affects olive oil quality and health-promoting properties

Olive oil, a functional food, is increasingly produced from trees irrigated with water containing high concentrations of salts. We studied the effects of irrigation-induced salinity on quality and health-related compounds in olive oil. Trees (cv Barnea) were grown in lysimeters with continuous control and monitoring of root-zone salinity. Salinity in the root zone was altered by changing irrigation solution salinity or by changing the extent of leaching. Extracted oil was analyzed for quality parameters including free fatty acid content, polyphenol, tocopherol, sterol and carotenoid levels, fatty acid (FA) profile, and antioxidative capacity.

While not all parameters changed, fruit water percentage and fruit oil content significantly decreased with increasing exposure to salt. As salinity increased, there was a desirable rise in measured polyphenol and tocopherol levels and a contrasting undesirable reduction in a number of important compounds, including 16:1 and 18:3 FA.

The possible negative effects on olive oil quality due to FA-related parameters should concern producers dependent on, or considering, irrigation with high-salinity water sources. A number of important quality parameters were differentially influenced by the method of inducing the root zone salinity, suggesting that additional environmental variables leading to oxidative responses were affected by the treatments. © 2018 Society of Chemical Industry.