Edible Corn-zein-based Coating Incorporated with Nisin or Lemongrass Essential Oil Inhibits Listeria monocytogenes on Cultured Hybrid Striped Bass, Morone chrysops x Morone saxatilis, Fillets During Refrigerated and Frozen Storage

Listeria monocytogenes presents a serious threat to consumer safety because it is resistant to various food storage techniques, including reduced or modified atmosphere packaging, refrigerated storage, and increased salt concentration. 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 (LGEO; 8%) were evaluated for antibacterial action against L. monocytogenes and spoilage organisms on fresh, cultured hybrid striped bass, Morone saxatilis x Morone chrysops, under two storage conditions (refrigerated or frozen) and two packaging types (polyvinyl chloride [PVC] and vacuum packing) over time. Corn-zein-based edible coatings were found to be an effective carrier for nisin and LGEO. Fillets coated with nisin showed the largest decrease in L. monocytogenes cell counts in both PVC and vacuum-packaged samples in both refrigerated and frozen product, while fillets coated with LGEO showed intermediate inhibition of L. monocytogenes cell counts, with the strongest LGEO antibacterial effect being found in frozen product regardless of packaging. Both nisin and LGEO treatments were most effective in PVC-packaged fillets compared to vacuum-packaged fillets, but the difference in bacterial loads between packaging methods was minor. Bacterial loads on refrigerated product tended to increase slightly after 5-d storage regardless of coating treatment or packaging, whereas bacterial loads on frozen product remained stable or decreased with time up to 60 d regardless of coating treatment or packaging. Data from the present study indicate that application of edible coatings incorporated with essential oils not only promotes food product safety but also may satisfy the preferences of consumers.