Edible antimicrobial films based on chitosan matrix

Edible chitosan coatings showed anti-Listeria monocytogenes effect evaluated by numeration and epifluorescence methods, Imparting a strong localized functional effect at the food surface by active packaging. The use of film-forming solution in culture liquid medium showed a known flocculant phenomenon combined with bactericidal activity keeping 20% of the initial microbial charge as viable cells in flocculant, which could develop subsequently. However, chitosan film showed 100% of L. monocytogenes inhibition for at least 8 d, completed by bactericidal activity measured by epifluorescence assays. A decrease in antibactericidal effect with time was obtained, most probably due to a decreasing availability of amino-groups of chitosan. Latter results were Validated on Emmental cheese samples using L. innocua as model strain because of its nonpathogenicity.