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 a nd below. To identify a possibly effective treatment, carcasses were s ubjected to water of temperatures between 60 and 90-degrees-C and trea tment times between 20 and 90 s each time/temperature treatment being applied to a batch of five carcasses. Each carcass was swabbed over 10 0 cm2 at each of four regions of the surface. Two of the regions selec ted for sampling had been shown to receive high flows of water while t he other two received relatively low water flows. The swabs from the e quivalent areas of the five carcasses in each batch were combined to g ive four composite samples. The numbers and composition of the microfl ora 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 b y two orders of magnitude, while non-thermoduric, spoilage bacteria we re reduced from about 50% to about 10% of the population. Increasing t he water temperature above 85-degrees-C or the treatment time beyond 2 0 s did not obviously reduce the numbers further, or alter the composi tions of the surviving flora. Subsequently, a batch of 800 carcasses w ere subjected to a treatment with water of 85-degrees-C for 20 s durin g 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 ob tained for each region. Samples were similarly collected from 100 untr eated carcasses. Each swab was separately processed for enumeration an d identification of the recovered flora, and for enumeration of Escher ichia coli. The results indicated that the treatment consistently redu ced the log10 numbers of spoilage bacteria and of E. coli by 2.5 over the whole surface of each carcass.