SUSCEPTIBILITY OF PREEVISCERATION WASHED BEEF CARCASSES TO CONTAMINATION BY ESCHERICHIA-COLI O157-H7 AND SALMONELLAE

Prerigor bovine cutaneous truncii muscle was subjected to a simulated preevisceration wash procedure 10 min after the hide was removed from the carcass. Five minutes after washing, the preevisceration washed tissue and unwashed control tissues were contaminated with a direct application of either flesh bovine manure or bovine manure which had been inoculated with five-strain mixtures of either Escherichia coli O157:H7 or salmonellae to simulate fecal contamination on a carcass. The manure which was inoculated with the bacteria had been previously irradiated to eliminate enterobacteriaceae. The contamination was allowed to adhere to the tissues for 10 min and then washed off with distilled water. Surface free energy of the preevisceration washed tissue was significantly lower than that of tissue which had not been subjected to preevisceration washing. Scanning electron micrographs of the tissue samples revealed plant material adhering to the surface of the control tissues, but not to the preevisceration washed tissues. Microbial populations of both total aerobic bacteria and enterobacteriaceae were approximately 0.7 log(10) unit greater on the control tissue, in comparison to the preevisceration washed tissue. Preevisceration washing may be beneficial in reducing the susceptibility of animal carcasses to further contamination.