In this study, antimicrobial packaging materials were developed by incorporating known concentrations (w/w) of essentials oils of oregano (Origanum vulgare) and thyme (Thymus vulgaris) into low-density polyethylene (LDPE), suitable for use as food packaging, via two different methods: ionizing treatment and directly by extrusion. The mechanical, barrier, and antimicrobial properties of the packaging were evaluated against the following foodborne pathogens: Salmonella typhimurium, Listeria monocytogenes, and Escherichia coli O157:H7. The results demonstrate that films developed by extrusion incorporating 4% (w/w) of essential oils had a higher inhibitory effect than those obtained using the ionizing treatment. The packaging developed by extrusion containing 1% (w/w) showed a positive inhibitory effect, while those obtained by the ionizing treatment had no inhibitory effect against any of the test microorganisms. The incorporation of essential oils on the LDPE films generated a plasticizer effect, whereas the ones obtained by means of ionizing treatment did significantly affect the barrier properties of the films. The results of this study showed that plantderived essential oils could be incorporated in active films for food packaging.

The influence o f B-ionizing radiation on chemical structure and mass transfer phenomena was studied in the principal flexible food packaging materials (LDPE and OPP). No significant changes were observed in the structure of polymer matrices or in oxygen permeability and global migration after ionizing the materials at dose levels approved for food products (