Evaluation of carcass scraping to enumerate bacteria on prechill broiler carcasses

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 cm(2) 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.