Wide-spectrum Antimicrobial Packaging Materials Incorporating Nisin and Chitosan in the Coating

Nisin and/or chitosan were coated, in 3% concentrations, onto paper with a binder medium of vinyl acetate-ethylene co-polymer to provide antimicrobial activity for use in food packaging. The combined use of nisin and chitosan in the coating was an attempt to give a wide antimicrobial spectrum that could inhibit the growth of several food spoilage and poisonous microorganisms. The migration of the preservative from the coatings to water was evaluated at 10°C and related to the suppressed microbial growth in the water and microbial medium. After 8 days, 8.1-8.3% of nisin and 1.0-1.2% of chitosan had migrated, and the migration of each was not affected by the presence of the other. The paper coated with nisin was more effective than the chitosan-coated paper in inhibiting the Gram-positive bacterium, Listeria monocytogenes, whereas the latter was more effective against Escherichia coli O157:H7. Combined inclusion of nisin and chitosan in the coating gave antimicrobial activity against both bacterial strains, and could improve the microbial stability of milk and orange juice stored at 10°C.