Extent of Beef Carcass Contamination with Escherichia coli and Probabilities of Passing U.S. Regulatory Criteria

In the 1996 U.S. Meat and Poultry Inspection Regulations, Escherichia coli biotype I counts were included as “performance criteria” of the slaughtering process. The criteria were based on a three-class attributes sampling plan applied in a moving window. The values for m and M and c and n were set at 5 and 100 CFU/cm², and 3 and 13 samples, respectively, for beef carcasses after overnight chilling following slaughter. In this study, beef carcasses were analyzed for counts of E. coli, and the results were expressed according to the above criteria. Furthermore, probabilities of passing E. coli performance criteria were determined. Carcasses were sampled in seven slaughtering plants (four steer and heifer; three cow and bull), during two seasons, and at three plant locations (pre-evisceration, after final carcass washing, and after 24 h of carcass chilling). Each entire carcass sample (100 cm² from the brisket, flank, and rump) was analyzed individually for E. coli counts. Compared with the regulation, which set the value of m and the acceptable range based on the 80th percentile of E. coli contamination data from U. S. Food Safety and Inspection Service nationwide baseline studies, our results showed that, on the average and depending on plant and season, 84.2 to 100% of the chilled carcass samples were in the acceptable range. The average percentages of chilled samples in the unacceptable range, set at the 98th percentile, were 0 to 6.7%. Depending on plant and season, the overall probabilities of chilled carcasses passing the regulatory requirement were 0.597 to 1.0 (brisket), 0.471 to 1.0 (flank), and 0.485 to 1.0 (rump). The results indicated substantial variation among plants and between seasons in ability to meet the E. coli performance criteria.