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. S kin samples were immersed in sterile tap water (control) or an 8%, 10% or 1 2% solution of TSP at 20 degreesC for 15 min. Surface pH values and mesophi lic and psychrotrophic plate counts were determined after 0, 1, 3 and 5 day s of storage at 2 degrees C. After washing, bacterial populations were sign ificantly 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 co ntrols ranged between 0.95 log(10) cycles and 1.78 log(10) cycles in the ca se of mesophilic microorganisms, and 0.92 log(10) cycles and 1.94 log(10) c ycles in the case of psychrotrophic strains. These differences between the concentrations of bacteria in samples immersed in water and those treated w ith TSP increased over time, ranging from 2.35 log(10) cycles to 3.08 log(1 0) 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, ra nging between 8 and 9 in skin treated with TSP, depending on the concentrat ion, while it was two units lower in the control samples.