Properties of nisin-incorporated polymer coatings as antimicrobial packaging materials

Nisin was incorporated into binder solutions of acrylic polymer and vinyl acetate-ethylene co-polymer, and then coated on to paper. Diffusive migration of incorporated nisin and the antimicrobial activity of the polymer coatings were investigated in order to understand the way of controlling nisin migration and the extent of microbial suppression by the coated paper. Vinyl acetate-ethylene copolymer exhibited a faster rate and higher degree of migration into aqueous food simulant solutions compared to acrylic polymer, and also exhibited a higher degree of suppression against Micrococcusflavus ATCC 10240 inoculated into the microbial medium. Addition of NaCl, sugar and citric acid to water significantly reduced the rate of diffusion of nisin in the case of acrylic polymer, while only slight change was observed due to the additive for vinyl acetate-ethylene copolymer. The simulant type slightly affected the equilibrated migration level of nisin. When the nisin-incorporated coatings were in contact with pasteurized milk and orange juice at 10degreesC, significant suppression of total aerobic bacteria and yeasts was observed without any noticeable difference between the two types of coatings. Copyright (C) 2002 John Wiley Sons, Ltd.