Invisible antimicrobial wrapper protects poultry.
Investigators added nisin to the zein edible film to enhance its effectiveness. For example, chicken may be covered with a transparent colorless film that is carrying a bacteriocin. The idea would be to prevent post-processing recontamination of cooked foods.
Scientists used a chicken breast with L. monocytogenes on it as an example. Processors could put the zein film containing nisin on the breast. The nisin molecule is within the film, allowing it to come in contact with the chicken surface, killing the Listeria. The tests showed that chicken cubes inoculated with Listeria experienced significant reductions of the bacteria upon the application of nisin, with no detectable levels by the end of a 28-day trial. The zein film also prevented the Listeria from growing back.
By putting calcium propionate with the nisin, levels of bacteria were reduced to non-detectable levels sooner. The calcium propionate enhanced the activities of nisin, we're told.
Zein film can prevent recontamination of ready-to-eat meat during processing. Chicken patties, for example, are cooked and then frozen or packaged. But before they are frozen, the patties are dipped in the film solution. The importance of such protection is underscored by the U.S. government's regulatory stance on L. monocytogenes: zero tolerance. If any of this pathogen is found on a 25-g to 50-g sample of a cooked meat or poultry product, it has to be recalled.
Industry has shown interest in the process. One company has expressed interest in an application for cubed chicken. But additional regulatory approval is necessary before the process can be used. Zein film and calcium propionate may be applied to ready-to-eat meats, but the addition of nisin would have to be specifically approved. Nisin is approved in the United States by the FDA only for use on soft cheese to control C. botulism.
Further information. Michael Johnson; phone: 501-575-4605; fax: 501-575-6936.
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|Publication:||Microbial Update International|
|Date:||Dec 1, 2000|
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