Evaluation of the hygienic performances of the processes for beef carcass dressing at 10 packing plants.

The hygienic performances of the carcass dressing processes at 10 beef packing plants were assessed from small sets of microbiological data. For each process, a single sample was obtained from a randomly selected site on each of 25 randomly selected beef sides leaving the process. In addition, during a period of about a year, a further nine such sets of samples were obtained from each of two of those processes. The aerobic bacteria, coliforms and Escherichia coli recovered from each sample were enumerated. For each set of 25 counts, values for the mean log and standard deviation were calculated on the assumption that the log values were normally distributed, and the log of the arithmetic mean was estimated for each set from the mean log and the standard deviation. The processes were ranked with respect to the log mean numbers of E. coli, coliforms and total counts estimated for the products. Log mean numbers of E. coli, coliforms and total counts ranged from about 2 to < 100 cm-2, from about 3 to < 100 cm-2, and from about 5 to about 2 cm-2, respectively. For one of the processes, 8, 7, and 8 of the log mean values for the replicated sets of aerobic, coliform and E. coli counts, respectively, differed by < 1 log unit. For the other process 5, 7, and 9 of the log mean values for the replicated sets of aerobic, coliform and E. coli counts, respectively, differed by < 1 log unit. These results indicate that the first process was generally consistent in the contamination of carcasses with aerobes, coliforms and E. coli. The contamination of carcasses in the second process with coliforms and E. coli was also generally consistent, but contamination of those carcasses with aerobes was inconsistent. The findings suggest that beef carcass dressing processes can be operated consistently with respect to the bacterial contamination of carcasses, and that log mean numbers of 1 +/- 0.5 to 100 cm-2, 1 +/- 0.5 to 100 cm-2 and 3 +/- 0.5 cm-2 for E. coli, coliform and total counts, respectively, may be appropriate, commercially attainable acceptance criteria for the hygienic performance of beef carcass dressing processes.