Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 26, 2005
Publication Date: February 6, 2006
Citation: Cason Jr, J.A., Berrang, M.E., Smith, D.P. 2006. Recovery of bacteria from broiler carcasses rinsed zero and twenty-four hours after immersion chilling. Poultry Science. 85(2):333-336.
Interpretive Summary: Under current rules of inspection, chilled broiler chicken carcasses are tested for presence of Salmonella and numbers of E. coli. Passing and failing scores are determined in comparison to baseline sampling, but microbiological methods are slightly different for inspection samples, which are taken about 24 hours earlier than the baseline samples. This study compared Salmonella incidence and E. coli bacteria in chicken rinses taken 0 and 24 hours after chilling. Numbers of E. coli were significantly higher in the earlier samples, but there was no difference in detection of Salmonella. More studies are needed to compare results at the two sampling times.
The Pathogen Reduction/Hazard Analysis Critical Control Point rule for broiler chicken processing, also known as the Mega-Reg, requires that randomly selected carcasses be tested for presence of Salmonella or numbers of E. coli in whole carcass rinse samples taken immediately after chilling. The results are compared against Salmonella performance standards and E. coli performance criteria based on the findings of the 1996 broiler chicken baseline survey in which chilled carcasses were shipped overnight and rinsed the following day. To test whether carcass rinses done immediately after chilling can be compared to rinses 24 h after chilling, 20 whole broiler carcasses exiting the chiller of a broiler processing plant were sampled on 3 days. Carcasses were bagged aseptically and rinsed for 1 min in 400 ml of sterile water. Recovered rinse liquid was poured into a sterile container, rinsed carcasses were placed in clean plastic bags, and all materials were held overnight at 4º C. On the following day, all carcasses were rinsed again in 400 ml of sterile water as before, and all rinse samples were cultured by standard methods to enumerate coliforms, E. coli, and Campylobacter, and to determine incidence of Salmonella. Statistical analysis used paired comparisons between the same carcasses rinsed at 0 and 24 h after chilling, with numbers of bacteria expressed as log cfu/ml of rinse. In two of three replications, significantly higher numbers of coliforms and E. coli were found in the rinse samples taken immediately after chilling versus rinse samples done at 24 h. There were no differences in numbers of Campylobacter or incidence of Salmonella between rinses taken at 0 and 24 hours. More study is required to determine whether rinse samples performed at 0 and 24 h after chilling are microbiologically equivalent.