Efficacy of trisodium phosphate solutions in reducing Listeria monocytogenes populations on chicken skin during refrigerated storage

Chicken skin inoculated with 10(8) CFU/ml of Listeria monocytogenes was dipped for 15 min in sterile water (control) and in 8, 10, or 12% trisodium phosphate (TSP) solutions. Skin samples were stored at 2 degreesC for 5 days, with microbial monitoring on days 0, 1, 3, and 5 after treatment. Compared to the water dip, all TSP treatments significantly (P<0.05) reduced L. monocytogenes populations on chicken skin. The concentration of the TSP was a significant factor in reducing the populations of the bacteria at days 0, 1, 3, and 5 of refrigerated storage. For all sampling times, the best outcomes were attained with the highest TSP concentration studied (12%). Bacterial reductions in counts during the first day of storage were between 1.52 and 2.70 log(10) cycles for 8 and 12% TSP-treated samples, respectively. Significantly greater reductions were observed from the third day of refrigerated storage onward. This occurred largely because populations of L. monocytogenes on control samples increased somewhat, but on TSP-treated samples the pathogen remained practically constant. Differences between L. monocytogenes counts in skin samples immersed in water and those treated with TSP ranged from 2.10 (8% TSP-treated samples) and 3.63 (12% TSP-treated samples) log(10) cycles on day 5 of storage. These results indicated that TSP is effective against L. monocytogenes in chicken meat, especially after several days of refrigerated storage.