Author
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Dorsa, Warren |
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Siragusa, Gregory |
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Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/3/1997 Publication Date: N/A Citation: N/A Interpretive Summary: The purge or meat juice found at the bottom of a commercial beef combo (a large, plastic lined, cardboard box containing about 2000 pounds of deboned beef used for grinding) was determined to be a representative sample for the bacterial content of this raw product. In the laboratory, purge was sampled from model beef combos that had been contaminated with bovine feces (Phase 1) or with Escherichia coli O157:H7 (Phase 2). During the initial tests, data indicated a strong relationship between the general bacteria counts derived from the purge samples of a model combo of beef and the general bacteria present in a rinse sample of the entire model combo of beef. In another test, E. coli O157:H7 was retrievable from the purge after 24 h regardless of where a piece of contaminated meat was placed within a 2.5-ft column of meat. This demonstrates bacteria do migrate downward into the purge of a model beef combo. In a third test 90 beef combos were randomly selected at the receiving dock of a commercial grinding facility and sampled using both purge and corresponding core samples (beef chunks). Purge samples from these combos recovered significantly greater numbers of general bacteria, coliforms (fecal bacteria), and E. coli than core samples from the same combos. Additionally, coliforms and E. coli were recoverable from 100 and 80 percent, respectively, of the purge samples taken, and 60 and 40 percent, respectively, from core samples from the same combos. These findings indicate that a purge sample from a beef combo is a more representative sampling method for determining the general bacterial content of that combo. Technical Abstract: The purge from model beef combos was tested as a means of representatively sampling the microbial content of this raw product. Purge was sampled from model beef combos that had been inoculated with bovine feces (Phase 1) or inoculated with an antibiotic resistant Escherichia coli O157:H7 (Phase 2). Data from Phase One indicated a strong correlation (r = 0.94) between the total aerobic bacteria counts derived from the purge samples of a model combo of beef and the total aerobic bacteria present in a rinse sample of the entire model combo of beef. In Phase Two, the marked E. coli O157:H7 was retrievable after 24 h regardless of the location of the inoculated pieces of meat within the 75-cm meat column, demonstrating that bacteria do migrate vertically downward into the purge of a model beef combo. Consequently, a third phase of the study was conducted where 90 beef combos were randomly selected at the receiving dock of a commercial grinding facility and sampled using both purge and concurrent 11 g core samples. Purge samples from these combos recovered significantly greater numbers of mesophilic and psychrotrophic aerobic bacteria, coliforms, and E. coli than core samples from the same combos. Additionally, coliforms and E. coli were recoverable from 100 and 80 percent, respectively, of the purge samples taken, while core samples were only able to recover 60 and 40 percent, respectively, from the same combos. These findings indicate that a purge sample from a beef combo is a more efficacious sampling method for determining the general bacterial profile and identifying the presence of coliforms and E. coli than randomly taken core samples. |
