Effects of Electron Beam Radiation on the Phenolic Composition and Bioactive Properties of Olive Pomace Extracts

Olive pomace is an agro-industrial waste product generated from the olive oil industry and constituted by bioactive compounds with potential applications in several industrial sectors. The purpose of this work was to evaluate the effects of electron beam (e-beam) radiation on olive pomace, specifically on phenolic compounds (by HPLC-DAD-ESI/MS) and the bioactive properties (antioxidant, antiproliferative, and antimicrobial activities) of crude olive pomace (COP) and extracted olive pomace (EOP) extracts. The amount of total flavonoid content and the reducing power of COP extracts were higher than those obtained for EOP extracts. The results suggested that e-beam radiation at 6 kGy increased both total phenolic and total flavonoid contents as well as the reducing power of COP extracts, due to the higher extractability (>2.5-fold) of phenolic compounds from these samples, while decreasing the scavenging activity of extracts. The extracts of both olive pomaces showed antibacterial potential, and COP extracts at 400 µg/mL also presented antiproliferative activity against A549, Caco-2, 293T, and RAW264.7 cell lines, with both properties preserved with the e-beam treatment. All in all, e-beam radiation at 6 kGy appears to be a promising technology to valorize the pollutant wastes of the olive oil industry through enhancing phenolic extractability and bioactive properties, and, furthermore, to contribute to the environmental and economical sustainability of the olive oil industry.