Note.: Effect of trisodium phosphate on mesophilic and psychrotrophic bacterial flora attached to the skin of chicken carcasses during refrigerated storage

The potential for using trisodium phosphate (TSP) to reduce mesophilic and psychrotrophic populations on the skin of chicken carcasses was explored. Skin samples were immersed in sterile tap water (control) or an 8%, 10% or 12% solution of TSP at 20 degreesC for 15 min. Surface pH values and mesophilic and psychrotrophic plate counts were determined after 0, 1, 3 and 5 days of storage at 2 degrees C. After washing, bacterial populations were significantly smaller in the samples treated with TSP than in the controls. The concentration of the TSP solution was a significant factor in reducing the populations of the bacteria on chicken skin. Before storage, the reduction in the presence of bacteria achieved in treated samples with respect to controls ranged between 0.95 log(10) cycles and 1.78 log(10) cycles in the case of mesophilic microorganisms, and 0.92 log(10) cycles and 1.94 log(10) cycles in the case of psychrotrophic strains. These differences between the concentrations of bacteria in samples immersed in water and those treated with TSP increased over time, ranging from 2.35 log(10) cycles to 3.08 log(10) cycles (mesophilic microorganisms), and from 2.79 log(10) cycles to 4.09 log(10) cycles (psychrotrophic microorganisms) on day 5 of storage. The pH of the skin remained more or less constant throughout the study period, ranging between 8 and 9 in skin treated with TSP, depending on the concentration, while it was two units lower in the control samples.