Ultrasonic-assisted enrichment of sunflower oil with leave powder from four Mediterranean olive cultivars: Chemical profiling, functional potential and impact on UV induced oxidation

This study explores the potential of olive by-products in functional food formulations by assessing the impact of olive leaves (OL) powder from four Mediterranean cultivars on the quality and oxidative stability of sunflower oil. The enriched unsaturated oils were subjected to UV irradiation for 8 hours as a powerful catalyst for oxidative reactions. The chemical profiling of olive leaves was performed by measuring mineral content (MC), and protein content (PC). Key indicators of oxidative stability such as free fatty acids, peroxide value, p-anisidine value, and Rancimat tests were evaluated in the enriched oils. The MC of OL varied widely among the cultivars, with the primary macro-elements ranked in the following order P < Mg < K < Ca. The main micro-elements were iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn). Our findings indicate that OL are a valuable source of PC (8.91–9.55 g/100 g). After the enrichment with OL from different cultivars, the results showed significant (p < 0.05) improvements in the oxidative stability of enriched sunflower oil (SO) at both concentrations (0.1 and 0.2 %) compared to the non-enriched control. This was evidenced by the slower degradation rates of the parameters monitored during 8 hours during the exposure to UV irradiation. However, the addition of OL had no significant effect (p > 0.05) on the fatty acid profile or iodine value. Furthermore, SO enriched with OL demonstrated overall acceptability in the sensory evaluation. These findings suggest that OL provide both health and technological benefits and could be used as natural stabilizers in food applications.