Effectiveness of antimicrobial packaging in controlling the growth of Listeria monocytogenes on cold-smoked salmon

Cold-smoked salmon (CSS) has been classified a high-risk product for Listeria monocytogenes contamination. The objective of this study was therefore to examine if antimicrobial packaging could be used as a hurdle to inhibit L. monocytogenes on the surface of this food. Low density polyethylene (LDPE) films incorporating nisin at a level of 2000 IU/cm2 placed on CSS inoculated with 5 x 10 2 CFU/cm2 of L. monocytogenes (LM) reduced the LM counts by 3.9 log CFU/cm2 (compared with control) after 56 (4°C) and 49 (10°C) days of storage while reductions of 2.4 and 0.7 log CFU/cm2 were achieved for samples inoculated with a high level of L. monocytogenes (5 x 105 CFU/cm2) after 58 (4°C) and 43 (10°C) days, respectively. For samples packaged in film coated with 500 IU/cm2 of nisin, reductions ranged between 0.5 and 1.8 log CFU/cm2. Nisin also inhibited the proliferation of background microbiota on smoked salmon and achieved shelf-life extensions of 21 and 28 days at 4°C and 5 and 7 days at 10°C with nisin incorporated at levels of 500 and 2000 IU/cm 2, respectively. LDPE packaging films and cellulose edible coatings incorporating nisin (500 IU/cm2) in combination with 0.3% potassium sorbate (PS) or 0.3% potassium sorbate (PS) and 0.1% sodium benzoate (SB) were found to reduce the populations of L. monocytogenes and spoilage miocrobiota by a maximum of 2.7 and 5.6 log CFU/cm2 respectively after 4 weeks of refrigerated storage.