Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2005
Publication Date: 7/20/2005
Citation: Bosilevac, J.M., Shackelford, S.D., Brichta, D.M., Koohmaraie, M. 2005. Efficacy of ozonated and electrolyzed oxidative waters to decontaminate hides of cattle before slaughter. Journal of Food Protection. 68:1393-1398.
Interpretive Summary: Infection with Escherichia coli O157:H7 is associated with consumption of undercooked ground beef. This pathogen has caused outbreaks of disease that resulted in hundreds of illnesses and numerous deaths in the United States during the 1980s and 1990s. E. coli O157:H7 that contaminates beef during processing has been shown to originate on the hide. Interventions that reduce hide contamination and the subsequent carcass contamination are currently in use at some beef processing plants. Since we believe that hide interventions are perhaps the most effective means to reduce pathogens on beef, we are attempting to provide more alternatives to those currently in use. Ozonated water and electrolyzed oxidizing (EO) water are generally recognized as safe, and have been used in decontaminating fresh produce, which can also be contaminated with E. coli O157:H7. No information exists describing the potential utility of ozonated or EO waters as hide washing compounds. Therefore, these studies evaluated their use as wash steps to reduce hide contamination, in experiments that used cattle hides draped over barrels as a model system. Ozonated water was sprayed on hides for 10 s. EO water has two forms, alkaline and acidic. Both forms of EO water were applied sequentially for 10 s (alkaline first, then acidic). Following treatments two types of bacteria were counted, aerobic bacteria (APC) and Enterobacteriaceae (EBC), which indicated the level of hide cleanliness. Each hide was also tested for the presence of E. coli O157:H7. Treatment using ozonated water reduced APC of the hides by 99% and reduced EBC by 99.9%. EO water treatment reduced APC by 99.9% and EBC by 99.99%. Controls using only tap water applied at conditions that matched ozonated water treatment and EO water treatment (in temperature, time, and pressure) reduced APC by only 50% and 90%, respectively. Each control reduced EBC by almost 90%. The prevalence of E. coli O157 on hides was reduced by 65% by treatment with ozonated water and by 57% by EO water treatment. Control washes showed no significant effect on the prevalence of E. coli O157:H7. These results demonstrate that ozonated and EO waters can be used to decontaminate hides during processing and hold potential to reduce pathogens that can be transferred to the carcasses.
Technical Abstract: The hides of cattle are the source of Escherichia coli O157:H7 that contaminates beef carcasses during commercial beef processing. A number of interventions that reduce hide contamination and the subsequent carcass contamination are currently being sought. The objective of this study was to determine the efficacy of ozonated and electrolyzed oxidizing (EO) waters to decontaminate beef hides compared to similar water washing without the active antimicrobial compounds present. Experiments used cattle hides draped over barrels as a model system. Two ppm ozonated water was applied at 700 lb per square inch and 15°C for 10 s. Alkaline EO water and acidic EO water were applied sequentially for 10 s each at 700 lb per square inch and 60°C. Treatment using ozonated water reduced hide aerobic plate counts (APC) by 2.1 log10 CFU per 100 square cm and reduced Enterobacteriaceae counts (EBC) by 3.4 log10 CFU per 100 square cm. EO water treatment reduced APC by 3.5 log10 CFU per 100 square cm and reduced EBC by 4.3 log10 CFU per 100 square cm. Water controls that matched the wash conditions of the ozonated and EO treatments only reduced APC by 0.5 and 1.0 log10 CFU per 100 square cm, respectively, and each reduced EBC by 0.9 log10 CFU per 100 square cm. The prevalence of E. coli O157 on hides was reduced from 89% to 31% following treatment with ozonated water, and from 82% to 35% following EO water treatment. Control wash treatments showed no significant effect on the prevalence of E. coli O157:H7. These results demonstrate that ozonated and EO waters can be used as means to decontaminate hides during processing and hold potential as means to reduce pathogen load on beef hides, thereby reducing pathogens on beef carcasses.