DECONTAMINATION OF COMMERCIAL, POLISHED PIG CARCASSES WITH HOT-WATER

Polished, uneviscerated pig carcasses suspended from a processing rail at a commercial slaughtering plant were passed through a cabinet that delivered sheets of recycled hot water onto each carcass from above and below. To identify a possibly effective treatment, carcasses were subjected to water of temperatures between 60 and 90-degrees-C and treatment times between 20 and 90 s each time/temperature treatment being applied to a batch of five carcasses. Each carcass was swabbed over 100 cm2 at each of four regions of the surface. Two of the regions selected for sampling had been shown to receive high flows of water while the other two received relatively low water flows. The swabs from the equivalent areas of the five carcasses in each batch were combined to give four composite samples. The numbers and composition of the microflora from each composite sample was determined. For all regions of the carcass surface, as compared with untreated carcasses, treatment with water of 85-degrees-C for 20 s reduced the total numbers of bacteria by two orders of magnitude, while non-thermoduric, spoilage bacteria were reduced from about 50% to about 10% of the population. Increasing the water temperature above 85-degrees-C or the treatment time beyond 20 s did not obviously reduce the numbers further, or alter the compositions of the surviving flora. Subsequently, a batch of 800 carcasses were subjected to a treatment with water of 85-degrees-C for 20 s during otherwise normal production. Swab samples were collected from 100 of those carcasses selected at random. Each carcass was swabbed over one of the regions previously selected, an equal number of swabs being obtained for each region. Samples were similarly collected from 100 untreated carcasses. Each swab was separately processed for enumeration and identification of the recovered flora, and for enumeration of Escherichia coli. The results indicated that the treatment consistently reduced the log10 numbers of spoilage bacteria and of E. coli by 2.5 over the whole surface of each carcass.