University of Arkansas, Fayetteville Division of Agriculture


The ability to control growth of Listeria monocytogenes on ready-to-eat poultry products with the antimicrobials nisin, malic acid, and grape seed extract incorporated into whey-protein coatings was evaluated. The antimicrobials were incorporated into the coating solution alone and in combinations. One gram pieces of turkey frankfurters were coated with the coating solutions and then inoculated with L. monocytogenes and stored at 4°C for 28 days. The inhibitory effect of the coatings on turkey frankfurter pieces was evaluated on d 0, 7, 14, 21, and 28. Coatings containing 2% malic acid, 3% malic acid, and the combination of nisin (6,000 IU/g) and malic acid (1%) were the most effective in inhibiting the growth of L. monocytogenes. Malic acid at 2 and 3% concentrations reduced L. monocytogenes population by 2.0 log cycles compared to the control after 28 d. Combination of 1% nisin and 1% malic acid reduced the population of L. monocytogenes by 2.7 log cycles compared to the control after 28 d of storage at 4°C. Grape seed extract did not inhibit the pathogen effectively when used alone or in combination with malic acid or nisin. Results of this investigation demonstrate synergistic effects of nisin and malic acid, which can be effectively incorporated into whey-protein coatings to control the post-processing contamination of L. monocytogenes in ready-to-eat poultry products.