Nanostructured chitosan/monolaurin film: Preparation, characterization and antimicrobial activity against Listeria monocytogenes on ultrafiltered white cheese

Antimicrobial cellulose-chitosan (CC) films containing monolaurin (ML) (0.5 and 1%) were developed using the sol-gel method and characterized in terms of microscopic, structural, swelling, water solubility, and antimicrobial properties against Listeria monocytogenes in vitro and on ultrafiltered cheese during storage at 4 for 14 days. The results of antimicrobial activity revealed that the addition of ML significantly (p < 0.05) increased the diameter of the inhibition zone. Moreover, CC film did not show inhibitory activity on L. monocytogenes. Scanning electron microscope images showed zinc nanoparticle with the 20-100 nm size in the film. Moreover, Fourier-transform infrared spectroscopy analysis results confirmed successful introducing and binding of the ML in the double layer film. The addition of ML in CC film decreased the swelling index in a significant manner, whereas the solubility of the film increased. A significant increase in solubility with ML addition was also found for both CC incorporated ML films. The addition of 0.5 and 1% ML into CC films made a 2.4-2.3 log reduction in L. monocytogenes population on cheese after 14 days. The results revealed a suitable antibacterial activity of monolaurin incorporated CC film, which is applicable for use as cheese packaging to control L. monocytogenes.