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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Chemical Dehairing on the Prevalence of Escherichia Coli O157:h7 and the Levels of Aerobic Bacteria and Enterobacteriaceae on Carcasses in a Commercial Beef Processing Plant

Authors
item Nou, Xiangwu
item Rivera Betancourt, Mildred
item Bosilevac, Joseph
item Wheeler, Tommy
item Shackelford, Steven
item Gwartney, B - NCBA
item Reagan, J - NCBA
item Koohmaraie, Mohammad

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 17, 2003
Publication Date: November 20, 2003
Citation: Nou, X., Rivera-Betancourt, M., Bosilevac, J.M., Wheeler, T.L., Shackelford, S.D., Gwartney, B.L., Reagan, J.O., Koohmaraie, M. 2003. Effect of chemical dehairing on the prevalence of Escherichia coli O157:H7 and the levels of aerobic bacteria and Enterobacteriaceae on carcasses in a commercial beef processing plant. Journal of Food Protection. 66(11):2005-2009.

Interpretive Summary: There is substantial evidence that much of the bacterial contamination of hamburger is a result of contamination of beef carcasses during processing. Furthermore, it has been determined that the primary source of that bacterial contamination is transfer of matter from the animal's hide to the carcass during the process of hide removal. The objective of this experiment was to test the hypothesis that cleaning cattle hides by removing hair and extraneous matter before hide removal would result in improved microbiological quality of carcasses in commercial beef processing plants. To test this hypothesis, we examined the effect of chemical dehairing of cattle hides on the percentage of carcasses with E. coli O157:H7 on them and the level of bacteria on the carcasses. Samples from 240 control (conventionally processed) and 240 treated (chemically dehaired before hide removal) carcasses (immediately after hide removal) were obtained from a commercial beef processing plant. Bacterial counts were significantly lower on treated compared to control carcasses. E. coli O157:H7 was detected on a much lower percentage of treated carcasses (1%) than it was on control carcasses (50%). These data indicate that chemical dehairing of cattle hides is an effective intervention to reduce the incidence of hide-to-carcass contamination with pathogens. Presumably, successful hide cleaning could be achieved by methods other than chemical dehairing. Any effective hide intervention process incorporated into beef processing procedures should significantly reduce carcass contamination with E. coli O157:H7. Combining an effective hide intervention with subsequent carcass interventions should further improve the safety of beef and beef products.

Technical Abstract: The objective of this experiment was to test the hypothesis that cleaning cattle hides by removing hair and extraneous matter before hide removal would result in improved microbiological quality of carcasses in commercial beef processing plants. To test this hypothesis, we examined the effect of chemical dehairing of cattle hides on the prevalence of Escherichia coli O157:H7 and the levels of aerobic bacteria and Enterobacteriaceae on carcasses. Samples from 240 control (conventionally processed) and 240 treated (chemically dehaired before hide removal) hides (immediately after stunning but before treatment) and preevisceration carcasses (immediately after hide removal) were obtained from four visits to a commercial beef processing plant. Total aerobic plate counts (APC) and Enterobacteriaceae counts (EBC) were not (P > 0.05) different between cattle designated for chemical dehairing (8.10 and 5.91 log10 CFU/100 cm**2 for APC and EBC, respectively) and cattle designated for conventional processing (8.01 and 5.72 log10 CFU/100 cm**2 for APC and EBC, respectively). However, E. coli O157:H7 hide prevalence was higher (P < 0.05) for the control group than for the treated group (67 vs 88%). The bacterial levels were lower (P < 0.05) on the treated (3.48 and 1.41 log10 CFU/100 cm**2 for APC and EBC) than the control (5.49 and 3.23 log10 CFU/100 cm**2 for APC and EBC) preevisceration carcasses. Prevalence of E. coli O157:H7 was lower (P > 0.05) on treated than on control preevisceration carcasses (1 vs 50%). These data indicate that chemical dehairing of cattle hides is an effective intervention to reduce the incidence of hide-to-carcass contamination with pathogens. The data also imply that any effective hide intervention process incorporated into beef processing procedures would significantly reduce carcass contamination by E. coli O157:H7.

Last Modified: 8/22/2014
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