Chemical characterization and properties of a polymeric phenolic fraction obtained from olive oil waste

•A new polymeric phenolic fraction (PPF) has been identified and characterized.•PPF has a high capacity for sorption and desorption of hydroxytyrosol.•PPF is a good tool for the purification of hydroxytyrosol.•PPF has a strong antioxidant activity in a lipid system.

Polymeric phenolic fraction (PPF) was isolated by ethyl acetate extraction from hydrolyzed liquids from steam-treated alperujo and characterized. PPF is composed mainly of phenolic compounds with small amounts of carbohydrates, protein and ash. Phenols such as hydroxytyrosol (HT) and tyrosol were bound to PPF during the ethyl acetate extraction. Acid hydrolysis (3 N HCl for 10 min at 100 °C) was used to liberate HT from the PPF. The properties of both sorption and desorption of the PPF were studied to enhance the purification of HT, up to 100%. The antioxidant activities of the PPF were evaluated in vitro using ferric reducing power and DPPH radical scavenging, showing activity but lower than HT and TROLOX. The inhibition of primary oxidation of PPF was similar to both HT and vitamin E. These antioxidant activities of the PPF were not a result of the presence of HT or similar phenols.