Incorporation of bacteriocin in plastic retains activity and inhibits surface growth of bacteria on meat

The bacteriocin, nisin, was incorporated into a polyethylene based plastic film and retained activity against the indicator bacteria Lactobacillus helveticus and Brochothrix thermosphacta. Beef carcass surface tissue sections (BCT) topically inoculated with the psychrotrophic spoilage bacterium B. thermosphacta were vacuum-packaged both with and without wrapping with the nisin impregnated plastic and held at 4 degrees C. An initial reduction of 2 log(10) cycles of B. thermosphacta was observed with nisin-impregnated wrapped BCT within the first 2 days of storage. After 20 days of refrigerated storage B. thermosphacta populations from nisin impregnated plastic wrapped samples were significantly less than (P < 0.05) control vacuum-packaged samples; log(10)5.8 vs 7.2 cfu cm(-2) respectively Temperature abuse was simulated by shifting inoculated packs from 4 degrees C (after 2 days) to 12 degrees C. Again, by 20 days, the B, thermosphacta populations of treated samples wrapped with nisin impregnated plastic were significantly less than (P < 0.05) control vacuum-packaged samples. log(10)3.6 vs 6.3 cfu cm(-2) respectively. This work highlights the potential for incorporating antimicrobial peptides with a wider and different range of inhibitory activity directly into plastics of different properties for use in controlling food spoilage as well as preservation to enhance product microbial safety (C) 1999 US Government.