Enhancement of Soybean Oil Antioxidant Activity by Enrichment with Olive Leaves Extracts from Tunisian “Jéli and Octobry” Varieties

The main purpose of this work was to enrich the refined soybean oil with olive leaves extracts from two Tunisian varieties not explored yet (Octobry and Jéli). In the first part of the study, we were interested in the quantification of olive leaves total phenols content and their identification by HPLC analysis. In the second part, ABTS and DPPH methods were used to study olive leaves antioxidant activities. Results revealed significant levels of polyphenols respectively for Jeli and Octory. HPLC analysis of olive leaves extracts showed that the two varieties have the same chromatographic profile from a qualitative point of view; they just differ in the phenolic content. For both extracts, Rutin and Oleuropein were the most abundant phenolic compounds. Olive leaves extracts were characterized by an important antioxidant activity that improved the soybean oil oxidative stability compared to the control sample.