Functional film of ethylene vinyl acetate and co‐polyamide compound containing “Nisin” active substance

Abstract

This study deals with flexible films incorporating nisin for antibacterial active packaging purposes. A novel approach was used to gain control over nisin release profile from a thermoplastic film in order to enhance its antibacterial efficiency. This approach involves polymer blends of ethylene vinyl acetate copolymer and co‐polyamide at various ratios. It was shown that the release profile of an antibacterial substance from active packaging to foodstuff is a key factor concerning the antibacterial efficiency. Samples of 400[μm] were produced by using a laboratory twin screw compounder and a laboratory hot press. Samples were characterized for their migration kinetics, molecular interactions, mechanical properties, and water swelling properties. Antibacterial activity tests show that nisin incorporated films reduced bacterial count by different extents. Listeria ATCC 33090 was used as target bacteria (data not shown). Nisin migration profile to water medium was determined by Lowry's protocol. Scanning electron microscopy images and thermal analysis indicated that no significant molecular interactions occurred. Furthermore, droplet and co‐continues like morphology were seen at different polymer blend ratios. Osmotic pressure driven release mechanism appears to be the dominant migration mechanism, and diffusion kinetics was dominant. Results show that morphology of the polymer blend matrix alters the diffusion coefficient. In addition, water swelling characterization of different samples was done in order to reveal the relations with the diffusion coefficient. It seems that there is an inverse resemblance between water swelling and the diffusion coefficient trends.