U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


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Published in Letters in Applied Microbiology (2001) 33: 325-328.


Aims: The following polymers were developed: polyethylene (PE), a PE and polyethylene oxide (70% PE and 30% PEO; PE + PEO) blend, PE and nisin (PE + nisin), PE, nisin, and EDTA (PE + nisin + EDTA), and PE + PEO with nisin (PE + PEO + nisin).

Methods and Results: Of the polymers tested, PE and PE + PEO did not exhibit any antimicrobial activity against Brochothrix thermosphacta (BT); however, PE + nisin, PE + nisin + EDTA, and PE + PEO + nisin did. Beef surfaces were experimentally inoculated with 3·50 log10 cfu/cm2 of BT, vacuum packaged with each of the five polymers, and held at 4°C for 21 d. After 3 d at 4°C, BT was reduced > 1·70 log10 by PE + nisin and > 3·50 log10 with PE + nisin + EDTA or PE + PEO + nisin. By 21 d at 4°C, BT was reduced to 0·30 log10 cfu/cm2 when treated with PE + PEO + nisin.

Conclusions: It appears that PE + PEO + nisin or PE + nisin + EDTA were more effective for reducing BT, as compared to polymers composed of PE + nisin.

Significance and Impact of the Study: Nisin-incorporated polymers may control the growth of undesirable bacteria, thereby extending the shelf life and possibly enhancing the microbial safety of meats.