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 ti ssue and unwashed control tissues were contaminated with a direct appl ication of either flesh bovine manure or bovine manure which had been inoculated with five-strain mixtures of either Escherichia coli 0157:H 7 or salmonellae to simulate fecal contamination on a carcass. The man ure which was inoculated with the bacteria had been previously irradia ted to eliminate enterobacteriaceae. The contamination was allowed to adhere to the tissues for 10 min and then washed off with distilled wa ter. Surface free energy of the preevisceration washed tissue was sign ificantly lower than that of tissue which had not been subjected to pr eevisceration washing. Scanning electron micrographs of the tissue sam ples revealed plant material adhering to the surface of the control ti ssues, but not to the preevisceration washed tissues. Microbial popula tions of both total aerobic bacteria and enterobacteriaceae were appro ximately 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 furth er contamination.