TRIMMING AND WASHING OF BEEF CARCASSES AS A METHOD OF IMPROVING THE MICROBIOLOGICAL QUALITY OF MEAT

A study to compare procedures and interventions for removing physical and bacterial contamination from beef carcasses was conducted in six c arcass conversion operations that were representative of modern, high- volume plants and located in five different states. Treatment procedur es included trimming, washing, and the current industry practice of tr imming followed by washing. In addition, hot (74 to 87.8 degrees C at the pipe) water washing and rinsing with ozone (0.3 to 2.3 ppm) or hyd rogen peroxide (5%) were applied as intervention treatments. Beef carc asses were deliberately contaminated with bovine fecal material at > 4 .0 log colony-forming units (CFU)/cm(2) in order to be better able to observe the decontaminating effects of the treatments. Carcasses were visually scored by 2 to 3 trained personnel for the level of gross con tamination before and after treatment. Samples (10 by 15 cm, 0.3 to 0. 5 cm thick) for microbiological testing were excised as controls or af ter application of each procedure or intervention and analyzed for aer obic mesophilic plate counts, Escherichia coli Biotype I counts, and p resence or absence of Listeria spp., Salmonella spp., and Escherichia coli O157:H7. Average reductions in aerobic plate counts were 1.85 and 2.00 log CFU/cm(2) for the treatments of trimming-washing and hot-wat er washing, respectively. Hydrogen peroxide and ozone reduced aerobic plate counts by 1.14 and 1.30 log CFU/cm(2), respectively. In general, trimming and washing of beef carcasses consistently resulted in low b acterial populations and scores for visible contamination. However, th e data also indicated that hot- (74 to 87.8 degrees C at the pipe) wat er washing was an effective intervention that reduced bacterial and fe cal contamination in a consistent manner.