Chitosan films for the microbiological preservation of refrigerated sole and hake fillets

•Chitosan films showed bactericidal effects as an internal layer on fish.•Fish bacteria was considerably inhibited by the presence of chitosan.•Greater inhibition of the microbial growth occurred under vacuum packaging.

The effect of chitosan films for shelf-life extension of fresh fillets of hake (Merluccius merluccius) and sole (Solea solea) was evaluated over a 15-day storage at 4 ± 1 °C. Fish fillets wrapped in a chitosan matrix were individually packaged in air (AP) and under vacuum (VP). Microbiological analyses (total aerobic mesophilic bacteria, Pseudomonas, H2S-producing bacteria, lactic acid bacteria, Enterobacteriaceae and Listeria monocytogenes were carried out during the shelf-life. The microbial species were inhibited (p < 0.05) by the presence of chitosan films, especially under VP conditions. A significant (p < 0.05) increase of the lag phase and a reduction of the final microbial population were detected mainly for total aerobic mesophilic bacteria, H2S-producing bacteria and Pseudomonas. The present work demonstrates the biocide effectiveness of chitosan as an internal layer of the packaging material, offering a promising alternative which would enhance the quality of fish during refrigerated storage.