Purpose: This study evaluated an alternative test (Staged) technique for post-chill Salmonella, comparing it to the standard USDA protocol.
Methods: In three poultry processing facilities, a carcass was aseptically separated into parts after conducting the standard USDA carcass post-chill test. The parts were placed into a bag and allowed to rest for 20 minutes. After this period, 400 ml of Buffered Peptone Water (BPW) was poured into the bag and agitated for one minute. The BPW was collected and sent for laboratory testing using the standard USDA Salmonella PCR protocol. Since both tests were conducted on the same carcass, this allowed use of McNemar’s test to compare each test’s ability to detect Salmonella.
Results: A total of 8,131 test pairs were examined, resulting in odds of 9.8 (P<2.2 X 10-16) of a Staged test detecting a Salmonella positive when Postchill was negative (95% CI: 7.1, 13.8). Plant A (4,326 test pairs) exhibited an odds of 9.8 (P=<2.2. X 10-16; 95% CI: 6.6, 15.2), Plant B (1,896 test pairs) an odds of 7.3 (P=3.2 X 10-8; 95% CI: 3.1, 21.1), and Plant C (1,909 test pairs) an odds of 11.2 (P<2.2 x 10-16; 95% CI: 5.9, 25.2) that Staged would detect a Salmonella positive when Postchill was negative.
Significance: When Postchill and Staged test results were different, the Staged test was significantly more likely to detect a Salmonella positive carcass. The Staged test is likely a more accurate measure of first-processing performance than the current test selected by USDA for verification.