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 10degreesC 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 10degreesC. Copyright (C) 2003 John Wiley Sons, Ltd.