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United States Department of Agriculture

Agricultural Research Service

Title: Variation in Numbers of Bacteria on Paired Chicken Carcass Halves

item Cason Jr, John
item Berrang, Mark

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 24, 2001
Publication Date: January 1, 2002

Interpretive Summary: The number of bacteria on a processed chicken carcass may tell something about the processing history of that carcass. If a carcass has high numbers of certain kinds of bacteria, perhaps a specific contamination event took place during processing. If bacterial contamination occurs when a carcass touches a piece of processing equipment, for instance, then the area of the carcass that touched the equipment should be more contaminated than other surfaces on that carcass. Unless bacterial contamination occurs exactly on the midline of carcasses, or is general rather than specific, contaminated carcasses should have higher counts on one side than on the other. This study counted the numbers of several kinds of bacteria on opposite halves of carcasses to determine whether carcasses with high bacterial counts tend to have higher counts on one side of the carcass than on the other. Results indicated that opposite sides of individual carcasses had similar bacterial counts even on carcasses that had above average numbers of bacteria. Carcasses with high numbers of bacteria may not have been contaminated by something that happened during processing, so controlling processing based on carcasses with high numbers of bacteria may not be the best way to reduce bacterial contamination on chicken carcasses.

Technical Abstract: Bacterial counts from paired broiler carcass halves were examined for relationships between numbers and kinds of bacteria that might indicate fecal contamination. Broiler carcasses removed from a commercial processing plant just before chilling were split aseptically along the midline and each side was rinsed in 400 mL of phosphate buffered saline for one minute with either mechanical or hand shaking. Both halves of six carcasses were rinsed on four different days for each shaking method. Aerobic bacteria, coliforms, E. coli, and Campylobacter jejuni were enumerated and summed to obtain whole carcass counts. There were no significant (P<0.05) differences in numbers of bacteria recovered by the two rinse methods. For APC, coliforms, E. coli, and Campylobacter, correlations between paired left and right side counts were between 0.78 and 0.86. The correlation between whole carcass counts and absolute left-right differences was significant for APC (0.43), but was not significant for coliforms, E. coli, and Campylobacter, so higher whole carcass counts were not associated with higher counts on one side of the carcass. Correlations between different bacteria on whole carcasses were significant for E. coli-APC (0.39), E. coli-coliforms (0.67), and APC-coliforms (0.71), but other combinations had non-significant correlations. The correlation was not significant between E. coli and Campylobacter, a relatively fragile organism whose presence can be interpreted to indicate fairly recent fecal contamination. There were no indications that high E. coli counts on inspection-passed, pre-chill carcasses indicated recent fecal contamination.

Last Modified: 4/23/2014