Oxidative stability of olive oil enriched with oleaster leaves under accelerated storage conditions

Abstract

Olive oil is rich in natural antioxidants that conserve its quality under storage conditions. However, there is a growing need to improve the quality of olive oil under storage conditions using phenol-enriched olive oil. In the present study, olive oil from the Chemlali cultivar was enriched with wild olive tree leaves or oleaster. The oil composition was analyzed before and after accelerated storage conditions using a Schaal test. Standard oil parameters, including free acidity; peroxide value; iodine value; specific extinction K232 and K270; fatty acid profile, and polyphenolic, chlorophyll, and carotenoid content, were evaluated for the control olive oil (COO) and the enriched olive oil (EOO). Polyphenolic compounds were identified for COO, EOO, and oleaster leaf extracts (OLE) using high-performance liquid chromatography. Antioxidant activity was analyzed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’ azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) tests. The results showed that enriching the olive oil quantitatively and qualitatively improved the polyphenolic composition, pigment contents, and the antioxidant activity. The EOO was more resistant to oxidation under accelerated storage conditions. The addition of wild olive leaves also significantly improved the resistance of the olive oil to oxidation and can, therefore, be used as a source of natural antioxidants to improve the oxidative stability of edible oils.