Listeria monocytogenes is inhibited on fillets of cold-smoked sunshine bass, Morone chrysops × Morone saxatilis, with an edible corn zein-based coating incorporated with lemongrass essential oil or nisin

Ready-to-eat (RTE) foods have been identified as a high-risk food group because of the number of outbreaks caused by food-borne pathogens isolated from these products. As these items receive no further processing or heat treatment prior to consumption, bacterial pathogens such as Salmonella, Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes present a serious threat to consumer safety. Of particular concern, L. monocytogenes is resistant to various food storage techniques, including reduced or modified atmosphere packaging, refrigerated storage, and increased salt concentration. Cold-smoked fishery products have been implicated in a number of listeriosis cases, where it is estimated that between 6 and 36% of cold-smoked fish is contaminated with L. monocytogenes. Edible coatings incorporated with natural antimicrobials have been suggested to control pathogenic and spoilage bacteria on a variety of meat products. In this study, edible zein-based coatings incorporated with nisin and lemongrass essential oil (LG) (8%) were evaluated for antibacterial action against L. monocytogenes and spoilage organisms on cold-smoked, cultured hybrid striped bass, Morone saxatilis × Morone chrysops, under polyvinyl chlorine (PVC) and vacuum packaging for 14 days (PVC) and 42 days (vacuum packaging), respectively, at 4°C. In this study, corn zein-based edible coatings were found to be an effective carrier for nisin and LG. Nisin-treated samples were most effective against L. monocytogenes in both PVC and vacuum-packaged fillets, with a total reduction of 3.5 log and 3.7 log, respectively over the length of the storage time. LG-treated samples reduced L. monocytogenes cell counts by 2.5 log in PVC and 1.7 log in vacuum-packaged samples. Only LG-treated samples packaged in PVC were found to inhibit the growth of spoilage organisms. Because nisin- and LG-treated fillets reduced L. monocytogenes, they may be useful methods to improve food safety in smoked seafood.