The Impact of Chitosan-Divergicin Film on Growth of Listeria monocytogenes in Cold-Smoked Salmon

Abstract

The aim of this study was to evaluate the impact of chitosan film, with bacteriocin divergicin 35 incorporate, on growth of <i>Listeria monocytogenes</i> in Cold smoked salmon. The simples of Cold-smoked wild salmon were inoculated with <i>L. monocytogenes</i> and treated with chitosan (100 kDa, 94.7% de-acetylated) and divergicin M35 was stored for 3 weeks at 4-8°C. The compounds were applied to the fish flesh in the form of solution or dried film. The film reduced <i>L. monocytogenes</i> to below the detection limit (<50 cfu/g) and kept total counts below 10⁴ cfu per g compared to 10⁹ cfu per g in control samples while the effectiveness of the solution was very limited. The inhibitory activity of the film lasted for 3 weeks, while the solution had no effect on <i>L. monocytogenes</i> counts measured on day 14. The film provided a better preservation of fish color (redness) and firmness than others treatments, while the solution had little impact on these parameters. It kept the volatile basic nitrogen (17.5 mg N/100 g) below the control value 29.9 mg N/100 g. Divergicin-loaded chitosan film thus may represent an interesting alternative for the bio-preservation of cold-smoked fish.