D. P. Smith

Experiments were conducted to evaluate a scraping method for enumerating bacteria on broiler carcasses. In experiment 1, coliforms and Escherichia coli were determined by the whole-carcass rinse (WCR) method and by scraping the skin surface and rinsing the blade (BR). In each of 2 replicate trials, 4 prechill broiler carcasses were collected from 2 different commercial processing plants. The WCR method was conducted on each carcass, then a blunt edge blade was used to scrape an area measuring approximately 80 cm² of the breast (front) skin and on the back of the carcass. After scraping, each blade and adhering residue was rinsed in 30 mL of 0.1% peptone. One milliliter of rinsate each from the WCR and BR was plated to determine total coliforms and E. coli. In experiment 2, 6 carcasses were collected from a processing plant in each of 2 replicate trials. Carcasses were split, with one half scraped on all skin surfaces, and the other half remaining unscraped as a control; all halves were then subjected to half-carcass rinses using 200 mL of 0.1% peptone. Coliforms and E. coli were enumerated. Results from both experiments are reported as log cfu/mL. In experiment 1, mean coliform WCR counts (5.1) were significantly higher (P < 0.05) than back BR (2.8), which were higher than front BR (2.2). Mean E. coli WCR counts (4.5) were higher than back BR (2.4), which were higher than front BR (1.6). The counts for BR adjusted for the greater surface area sampled by WCR were still lower than the WCR counts. Experiment 2 results showed no difference between control and scraped carcass halves for coliforms (4.7) or E. coli (4.6). Overall, results showed that scraping either prior to or after rinsing did not increase enumeration of coliforms or E. coli. Scraping could be a viable method to compare the numbers of bacteria on different areas of the same carcass.

During processing, fecal material may contact broiler carcasses externally or internally. A study was conducted to determine the effect of external vs. internal fecal contamination on numbers of bacteria on broiler carcasses. In each of 3 trials, 12 carcasses just prior to evisceration were obtained from a commercial processing plant, placed on a shackle line, and eviscerated with commercial equipment in a pilot scale processing plant. Also, approximately 20 intestinal tracts were collected from the processing plant; then cecal contents were collected and pooled. One gram of cecal content was placed on the exterior breast skin (external), inside the carcass cavity (internal), or not applied (control). All carcasses were held 10 min, then placed on the shackle line and passed through a commercial inside-outside bird washer set at 552 kPa, 5 s dwell time, using approximately 189 L per min of tap water at ambient temperature. After a 1-min drip, whole carcass rinses were conducted on each carcass, and coliforms, Escherichia coli, and Campylobacter counts were determined and reported as log cfu/mL of rinse. External carcass contamination resulted in significantly higher (P < 0.05) coliform, E. coli, and Campylobacter numbers than internal contamination (5.0 vs. 4.5, 4.9 vs. 4.2, and 3.6 vs. 2.6, respectively). Control carcass counts were significantly lower than external or internal carcass contamination counts for coliforms (3.7), E. coli (3.6), and Campylobacter (2.2). External contamination resulted in higher numbers of bacteria after carcass washing, but carcasses with internal contamination still have higher numbers of bacteria after washing than carcasses without applied contamination.