Phenolic content and antioxidant activity of olive by-products and antioxidant film containing olive leaf extract

The antioxidant activity of olive leaf (OL) and cake (OC) extracts with different solvents was evaluated. 70% of aqueous ethanol extract of OL was chosen as the most antioxidant extract based on antiradical activity (DPPH) (95.4 +/- 0.3%) and oxygen radical absorbance capacity (ORAC) (0.82 +/- 0.07 g equivalent Trolox per g of solution) assays. This OL extract was incorporated in two multilayer materials consisting of (i) polyethylene/polyethylene (PE/PE) film and (ii) polyethylene/paper (PE/P). These multilayers were exposed to a gas stream enriched in free radicals to evaluate the scavenging capacity of both materials. PE/PE film exhibited the highest scavenging activity of free radicals (78.8%). Migration of the phenolic compounds from olive by-products into two simulants was performed and demonstrated a non-migrating behavior. The limits of detection and quantification for oleuropein were 0.5 mu g kg(-1) and 1.7 mu g kg(-1) and for Luteolin-7-O-glucoside 1.3 mu g kg(-1) and 4.3 mu g kg(-1) respectively. (C) 2016 Elsevier Ltd. All rights reserved.