Microbiological condition of carcasses and equipment and evaluation of a steam decontamination system in a pig slaughterhouse

The microbiological examination of environment and carcasses was conducted in a commercial pig slaughter facility with a maximum slaughter capacity of 200 animals per hour. To evaluate the microbiological condition of equipments, 270 samples were collected during the pig slaughtering and the cutting process, and 101 after the cleaning and disinfection procedures. Statistical analysis of environmental bacterial counts showed that cleaning and disinfection procedures not always were able to decrease significantly the number of bacteria. Regarding the carcass contamination, 108 half-carcasses were examined at the end of the slaughter line. Values pointed out for mesophilic count and E. coli on carcasses were higher than those indicated in the Decision 2001/471/CE. These results should lead to undertake concrete actions to avoid the repetition of such results. High microbial counts, together with the high Salmonella spp. and L. monocytogenes prevalence obtained, suggest that general hygiene standards alone are not sufficient to ensure food safety and reduce the risk of foodborne illness. To evaluate the effectiveness of steam pasteurization, a pilot-plant process which exposes the carcasses to steam before the evisceration step was developed, and 86 carcasses were sampled. After treatment, mesophilic counts were significantly reduced (P < 0.05) by up to 2.26 log10 CFU/cm2. The current study verified that the scaled-up commercial decontamination system is very effective in reducing the levels of natural mixed flora on surfaces of commercially slaughtered pig carcasses. Nevertheless, the decontamination must be considered as supplemental to a slaughter procedure already optimized in terms of hygiene, because it does not eliminate the consequences of slaughter under poor hygienic conditions.