Antimicrobial Effect of Different Chitosan Preparations against Selected Food Borne Pathogens

The antimicrobial effect of the polyamide 6/66-chitosan blend obtained by extrusion and chitosan-coated plastic films was compared with pure chitosan films and chitosan solution against Escherichia coli, Listeria monocytogenes and Bacillus cereus. The films from polyamide 6/66-chitosan blend had no antibacterial activity, and the chitosan plastic film coating (bilayer system) showed only contact inhibition, without increase of contact area. The pure chitosan films did not show inhibition halos, however, contact inhibition was observed. During the assays, this films absorbed moisture, increasing the diameter of the discs at least 30%, causing contact inhibition on the area in all microorganisms tested. The best inhibition effect was observed with chitosan solution, reaching the total inhibition for Listeria monocytogenes and a log reduction of 3.6 and 2.3 for Escherichia coli and Bacillus cereus, respectively. Chitosan has an antimicrobial effect, although this property was reduced by the incorporation of a plastic matrix.