Radical scavenging polyethylene films as antioxidant active packaging materials

Abstract

Most foods and beverages require the use of additives to avoid degradative reactions responsible for spoilage, yet consumers are demanding removal of such additives from product formulations. In the present work, fish protein hydrolysates (heretofore “peptides”), natural compounds with demonstrated antioxidant activity, were bound to polyethylene (PE) surface through a two-step conjugation. The films were activated by UV-ozone treatment, and polyethyleneimine (PEI) was used to tether the peptides. Surface characterization of control and modified films was performed using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), dye assays, contact angle and Trolox Equivalent Antioxidant Capacity (TEAC) after each functionalization step. Surface characterization confirmed the successful activation and functionalization of the PE through the incorporation of carboxylic acids and amines. The covalent attachment of the active peptides onto the PE surface was confirmed by the changes observed in dye assays results and introduction of characteristic absorbance bands in ATR-FTIR spectra. Surface wettability showed the increase of hydrophilicity after UV-ozone treatment, and amine and peptide conjugation. TEAC assay showed that the amount of peptide bounded was not enough to have radical scavenging capacity, however amine conjugated films showed ability to scavenge free radicals (~1.2 nmol Trolox/cm2) and thus prevent oxidation reactions in foods. Such radical scavenging active packaging materials offer a potential alternative to the use of antioxidant additives in food and beverage formulations, addressing consumer demands for clean labels while mitigating food waste and loss due to spoilage.