Pathogen Inhibition and Shelf-Life of Raw and Precooked Meat with Protamine

This project determined the antimicrobial activity of different levels of protamine, a natural antimicrobial, on Salmonella, E. coli and Listeria monocytogenes on meat and poultry before and after cooking.

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Objectives

To determine the antimicrobial activity of different levels of protamine on Salmonella, Escherichia coli, and Listeria monocytogenes inoculated onto meat and poultry before and after precooking; to measure the shelf- life and microbial status at 35, 40, and 50°F (abusive temperature) of precooked meat and poultry treated with protamine and packaged in vacuum and modified atmospheres (80% nitrogen:20% carbon dioxide); and to evaluate the flavor and odor profiles of stored precooked meat and poultry products treated with protamine through trained sensory panel determinations.

Conclusions

Protamine inhibited microorganisms in meat, concentrations of 10mg/g and above are required to reduce the load by more than 2 logarithmic units. At 10mg/ml, reductions of greater than 95% of the controls were achieved. For high levels of microbes of about 10⁶ cfu/g, this is not a significant reduction. The minimal inhibitory concentration of protamine against L. monocytogenes was 3mg/ml at pH 7.0. The last two objectives were not conducted because of the high concentration of protamine required to obtain one log reduction and inability of protamine to completely inhibit microbial growth.

Deliverable

This study demonstrated that protamine does not appear to have an application in RTE meat as a pathogen inhibitor.