COMPARISON OF WATER WASH, TRIMMING, AND COMBINED HOT-WATER AND LACTIC-ACID TREATMENTS FOR REDUCING BACTERIA OF FECAL ORIGIN ON BEEF CARCASSES

Cleaning treatments, such as high-pressure water wash at 35 degrees C or trim, alone and combined with sanitizing treatments, such as hot wa ter (95 degrees C at the source), warm (55 degrees C) 2% lactic acid s pray, and combinations of these two sanitizing methods, were compared for their effectiveness in reducing inoculated numbers (5.0 to 6.0 log CFU/cm(2)) of Salmonella typhimurium, Escherichia coli O157:H7, aerob ic plate counts, Enterobacteriaceae, total coliforms, thermotolerant c oliforms, and generic E. coli on hot beef carcass surface areas in a m odel carcass spray cabinet. Log reductions in numbers of all tested or ganisms by water wash or trim alone were significantly smaller than th e log reductions obtained by the different combined treatments. Regard less of the cleaning treatment (water wash or trim) or surface area, t he range for mean log reductions by hot water was from 4.0 to >4.8 log CFU/cm(2), by lactic acid spray was from 4.6 to >4.9 log CFU/cm(2), b y hot water followed by lactic acid spray was from 4.5 to >4.9 log CFU /cm(2), and by lactic acid spray followed by her: water was From 4.4 t o >4.6 log CFU/cm(2), for S. typhimurium and E. coli O157:H7. Identica l reductions were obtained for thermotolerant coliforms and generic E. coli. No differences in bacterial reductions were observed for differ ent carcass surface regions. Water wash and trim treatments caused spr eading of the contamination to other areas of the carcass surface whil e providing an overall reduction in fecal or pathogenic contamination on carcass surface areas. This relocated contamination after either wa ter wash or trim was most effectively reduced by following with hot wa ter and then lactic acid spray. This combined treatment yielded 0% pos itive samples for S. typhimurium, E. coli O157:H7, thermotolerant coli forms, and generic E. coli on areas outside the inoculated areas, wher eas percent positive samples after applying other combined treatments ranged from 22 to 44% for S. typhimurium, 0 to 44% for E. coli O157:H7 , and 11 to 33% for both thermotolerant coliforms and generic E. coli. From data collected in this study, it is possible to choose an effect ive, inexpensive treatment to reduce bacterial contamination on beef c arcasses. In addition, the similar reduction rates of total coliforms, thermotolerant coliforms, or generic E. coli may be useful in identif ying an indicator to verify the effectiveness of the selected treatmen t as a critical control point in a Hazard Analysis and Critical Contro l Point program.