Efficacy of optimized nisin-based treatments to inhibit Salmonella typhimurium and extend shelf life of broiler carcasses.
1995
Shefet S.M. | Sheldon B.W. | Klaenhammer T.R.
Nisin is an antimicrobial peptide produced by Lactococcus lactis subsp. lactis. Nisin exhibits a broad spectrum of inhibitory activity against gram-positive microorganisms such as Listeria monocytogenes and Clostridium botulinum. In previous studies, a method was developed using nisin in combination with food-grade chelating agents to inactivate Salmonella species and other gram-negative bacteria. The objectives of this study were to determine the efficacy of several optimized nisin-containing preparations for reducing the population of Salmonella typhimurium NAR on broiler drumstick skin and whole drumsticks and extending the shelf life of broiler drumsticks. In previous studies, a simplex algorithm was used to optimize the biocidal activity of nisin towards Salmonella by adjusting formula pH and adding varying concentrations of chelating agents (EDTA, citric acid) and a surfactant (Tween 20). From these studies, four optimal treatments were identified. These were tested more extensively in the present study. Significant reductions in viable S. typhimurium NAR populations on broiler drumstick skin were achieved and ranged from 3.1 to 4.9 log10 cycles following immersion for 30 min at 25 degrees C. The inhibitory activities of these four treatments against S. typhimurium NAR-contaminated drumsticks were also compared to treatments with 20 ppm chlorine. Numbers of survivors following a 30-min dip ranged from less than or equal to 10 to 2.57 X 10(1) organisms per ml of skin rinse for the nisin formulations versus 1.32 X 10(2) organisms per ml on the chlorine-treated drumsticks. In other studies, the shelf life of refrigerated broiler drumsticks was extended by 1.5 to 3 days following immersion for 30 min in one of the optimized nisin-containing treatments in comparison to drumsticks dipped in sterile distilled, deionized water.
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