Improved antimicrobial activity of nisin-incorporated polymer films by formulation change and addition of food grade chelator

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.