Improvement of the Olive Oil Quality with Olive Leaf Extract through Response Surface Technology

Olive oil was enriched by adding high added value olive leaf extract. After extracting the dried and ground olive leaves with the assistance of homogenizer, the dried extract was partially dissolved into the oil to increase the shell-life of the oil. A face central composite design (FCCD) through response surface methodology (RSM) was used to investigate the effects of enrichment conditions (extract content, time and mixing speed) on the responses, total phenolic content (TPC) and oleuropein concentration of the enriched olive oil. Furthermore, antioxidant activity of the oil was determined by 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) method. Additionally, oxidative stability of the enriched oil was assessed by the Rancimat method. Total carotenoid content (TCC), peroxide value (PV), tocopherol and chlorophyl were also measured, respectively. Finally, pure and enriched oil were compared according to those quality parameters.