Effect of γ irradiation on the antibacterial activity of poly lactic acid films encapsulated with essential oils against some common food borne pathogens

Abstract

The production of healthy, eco-friendly, sustainable, and active food packaging is necessary to replace the existing conventional synthetic packaging. The aim of this study is to develop new food packaging materials from polylactic acid (biodegradable polymer) encapsulated with volatile oils for the production of active packaging that has a functional effect on food borne pathogens (antibacterial properties) and to study the impact of gamma irradiation on the antimicrobial activity of these packages. Lemongrass essential oils (LGEO) and Cumin essential oils (CEO) and in combination (mix EOs), their incorporation complex into polylactic acid (PLA) films and the antibacterial activity of active PLA films before and after γ-irradiation (5 and 10 kGy) were studied against three important food pathogens; <i>Escherichia coli O157:H7, Listeria monocytogenes</i> and <i>Salmonella enteritidis</i>. Also, the mechanical and physical properties of the active films were evaluated. PLA/LGEO showed good stability with a suitable prolonged release of LGEO, resulting in improved antimicrobial activity compared to the PLA/CEO. Due to the synergistic effects of mix EOs, PLA/mix EOs films showed complete inactivation against tested bacteria, suggesting that the evolved PLA/mix EOs films have great potential for food active packaging applications, so PLA/mix EOs were selected for further analysis. Irradiation at dose 5 kGy has no significant effect on the antibacterial activity of PLA/EOs films, increasing the radiation dose to 10 kGy, resulted in a significant decrease in active PLA/EOs films antibacterial activity. The combination of lactic acid active packaging and 5 or less doses of gamma irradiation will have a synergistic effect against food borne pathogen, thus achieving the quality and safety of irradiated foods.