INHIBITION OF LISTERIA MONOCYTOGENES ON RAINBOW TROUT (ONCORHYNCHUS MYKISS) USING TROUT SKIN GELATIN EDIBLE FILMS CONTAINING NISIN

Contaminated food can pose high risk of listeriosis for susceptible populations. Listeria monocytogenes has been isolated from fresh, frozen and processed seafood products. Our goal in this study was to develop nisin-containing edible films using trout skin gelatin and test their effectiveness against L. monocytogenes on raw trout fillets (stored at 4 °C and 10 °C) as a strategy for reducing the risk of contamination. Films with 18 μg nisin/cm2 showed consistent inhibition and were chosen for storage studies conducted at 4 and 10 °C for 30 days. Trout fillets were challenged with 2 log CFU L. monocytogenes/g before or after coating with nisin-containing films. Films with nisin reduced L. monocytogenes counts below the detection limit (0.3 log CFU/g) at 4 °C. At 10 °C, a 0.3 to 1.1 log reduction was observed compared to controls by the end of storage. The effectiveness of treatments depended upon the concentration of nisin and storage temperature. The developed edible films have the potential to reduce pathogens on seafood and can be incorporated with a variety of antimicrobials.