Sustainable Reuse of Treated Wastewater in Olive Irrigation: Impacts on Oil Bioactive Compounds, Quality, and Safety

Abstract

This study evaluated the impact of irrigation with treated wastewater on the quality and safety of olive oil extracted from two cultivars (Picual and Koroneiki). Freshwater-irrigated orchards were used as control, while treated wastewater-irrigated orchards were used as treatment under a comparative experimental design. Olive fruits were analyzed for physicochemical properties, while extracted oils were evaluated for quality parameters, oxidative stability, bioactive compounds, fatty acid composition, and potential contaminants. Results showed cultivar-dependent variations in most parameters. Picual generally exhibited higher levels of bioactive compounds, including total phenolics and tocopherols, as well as greater oxidative stability compared to Koroneiki. Fatty acid composition was dominated by oleic acid in both cultivars, confirming good nutritional quality. Physicochemical indices, including free acidity, peroxide value, UV absorbance, saponification value, and refractive index, remained within international acceptable limits for extra virgin olive oil. Although treated wastewater irrigation slightly influenced some quality parameters, most differences between treatments were not statistically significant (p > 0.05). Heavy metals and pesticide residues, where detected, remained within permissible limits. Overall, the findings suggest that treated wastewater, when properly managed, does not adversely affect olive oil quality and may be considered a sustainable alternative irrigation source in olive cultivation