Control of Listeria monocytogenes on ready-to-eat foods using edible antimicrobial coatings and films

Abstract

Growth of Listeria monocytogenes in processed fishery products and meat products such as cold-smoked salmon, ham steaks and roasted turkey has become a major concern and an important food safety issue. The food industry therefore has incorporated hurdles to inactivate Listeria monocytogenes. The objective of this research was to examine if antimicrobial packaging could be used as a hurdle to inhibit Listeria monocytogenes on the surface of these food. Cold-smoked salmon samples were surface-inoculated with a five-strain cocktail of Listeria monocytogenes to a final concentration of 4.4 log10 CFU/cm2 and coated with chitosan coating solution or wrapped in chitosan films with or without the antimicrobials sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS)). The samples were vacuum packaged and stored at 4ºC for 30 days. The chitosan coatings, with or without the antimicrobials, were consistently more effective against Listeria monocytogenes than chitosan films of the same composition. Chitosan films containing 1.2% SL/0.25% SD or 2.4% SL and chitosan coatings containing 1.2% SL/0.25% SD or 0.15% PS/0.125% SD displayed the greatest anti-listerial activity. This study showed that chitosan-based edible coatings and films hold promise and can potentially assist fishery industries in their efforts to control Listeria monocytogenes.