|Hager, Janelle - Kentucky State University|
|Rawles, Steven - Steve|
|Xiong, Youling - University Of Kentucky|
|Newman, Melissa - University Of Kentucky|
Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2018
Publication Date: 4/16/2018
Citation: Hager, J.V., Rawles, S.D., Xiong, Y.L., Newman, M.C., Webster, C.D. 2018. 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. Journal of the World Aquaculture Society. 50(1):204-218. https://doi.org/10.1111/jwas.12523.
DOI: https://doi.org/10.1111/jwas.12523 Interpretive Summary: Detection of Listeria monocytogenes on seafood products is increasing as the bacteria is the main culprit for food poisonings when seafood is eaten by consumers. Post-processing treatments could decrease the risk to public when consuming seafood. The objective of this study was to see if edible coatings incorporated with generally-recognized-as-safe, natural compounds on reducing L. monocytogenes on the surface of fish fillets. Nisin, a broad-spectrum bacteriocin known for its anti-listerial properties, and lemongrass essential oil (8% v/v) were incorporated into an edible corn zein-based coating and applied to two post-processing treatments of hybrid striped bass (Morone saxatilis x M. chrysops): refrigerated (4 deg C) and frozen (0 deg) fillets. Fillets were packaged in either polyvinyl chloride (PVC) or under vacuum, and evaluated for activity against inoculated L. monocytogenes. Nisin and lemongrass essential oil (8%) were effective in significantly reducing cell counts of L. monocytogenes in all post-harvest storage methods. Coatings were able to reduce pathogenic Listeria on refrigerated and frozen fillets with reductions up to 4.27log on nisin and 2.05log on lemongrass EO treatments, respectively. This study indicates that edible coatings incorporated with natural antimicrobials are a promising post-harvest treatment to control the growth of L. monocytogenes on fish products; however, further research on the use of lemongrass essential oil, as well as detailed analysis of sensory effects are needed.
Technical Abstract: Listeria monocytogenes present 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 (HSB; Morone saxatilis x M. chrysops) under two storage conditions (refrigerated or frozen) and two packaging types (polyvinyl chlorine 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 days storage regardless of coating treatment or packaging, whereas bacterial loads on frozen product remained stable or decreased with time up to 60 days regardless of coating treatment or packaging. Data from the present study indicate that application of edible coatings incorporated with EOs promotes not only food product safety, but also may satisfy the environmental conscience of consumers.