Evaluation of an WPC edible film added with a cocktail of six lytic phages against foodborne pathogens such as enteropathogenic and Shigatoxigenic Escherichia coli

Abstract

Active packaging materials with antimicrobial properties have gained significant interest over the last decade. Furthermore, phages are potentially useful as antimicrobial agents in food. Phage stability assays were conducted in the whey protein concentrate (WPC) matrix over 5 weeks of storage. In addition, the phages incorporated in the WPC matrix were characterized by their release from films into an aqueous system and solid food, as well as by their antimicrobial activity against pathogenic E. coli in a liquid medium and in meat at refrigerated, room and abusive temperatures. The results demonstrate that phages are highly stable in WPC films within 5 weeks of storage. Moreover, WPC films can release a significant number of phages into an aqueous system and onto a meat surface at similar concentrations. Phage-added films produced a significant reduction in E. coli cells to non-detectable levels in antimicrobial assays. Similar results, such as a complete inactivation achieved for DH5α and O157:H7 STEC strains, were obtained when antimicrobial assays were performed on meat. As a conclusion, the six-phage cocktail added into WPC films was highly stable, effectively released from films and proved highly effective as a biocontrol tool, though not under all the conditions evaluated.