Supercritical Impregnation of Olive Leaf Extract to Obtain Bioactive Films Effective in Cherry Tomato Preservation

Abstract

The promising prospective in the use of natural extracts has encouraged researchers to study techniques for its incorporation into polymers. This study has focused on supercritical solvent impregnation (SSI) of polyethylene terephthalate/polypropylene (PET/PP) films with olive leaf extract (OLE). The % co-solvent and the ratio OLE/polymer (w/w) were evaluated for producing antioxidant (AO) films. Besides, the antimicrobial (AM) capacity of both OLE and impregnated films were studied against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enteritidis. The highest AO capacity and phenolic loading were found in films impregnated at 7% co-solvent and a ratio OLE/polymer of 1, where c.a. 5 mg AO/g and 60 μg total polyphenols/g films were obtained. The antimicrobial capacity of the impregnated films varied respecting that found in the extract, especially in the case of S. enteritidis and P. aeruginosa, The bioactivity of films was also demonstrated by extending cherry tomatoes’ shelf-life by 20 days.