Safety Zone
By: James Marsden

Food safety improvements in beef slaughter and carcass chilling

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(The views and opinions expressed in this blog are strictly those of the author.)

On May 4, 2009 USDA’s Food Safety and Inspection Service issued a Directive on verifying sanitary dressing and process control procedures in slaughter operations of cattle (  This Directive which goes into effect on June 1, 2009 is intended to assure that the beef slaughter process includes effective microbial interventions that reduce the risk of microbiological contamination on beef carcasses. It will certainly force beef packers to rethink their pathogen control strategies.


Since before the 1993 E. coli O157:H7 outbreak, much of the emphasis on beef safety has focused on slaughter interventions. This approach makes sense because at this point in the process, all of the microbiological contamination is limited to the surface of the carcass. The meat inside the carcass is completely free of bacteria until it is contaminated during fabrication. The major vectors of contamination during beef slaughter are hide removal, evisceration and the slaughter environment. Much can be done to control contamination from each of these vectors during the slaughter process. Hide removal and evisceration can be done in a sanitary manner and any visible contaminants can be removed using steam vacuuming.  Most beef slaughter plants utilize a combination of thermal pasteurization and organic acid treatments to further reduce microbiological contamination. Environmental contamination can be controlled by treating the air using low levels of vaporized Hydrogen Peroxide.


Ideally, this system should completely address microbiological contamination. It has resulted in improvements over the past several years, but unfortunately, problems with microbiological contamination on beef carcasses still exist. I see two potential problems with slaughter based interventions. (1) The time available to apply interventions is limited. Thermal and chemical interventions may not have the required residence time to achieve optimum effectiveness. And (2) the carcass chilling process may contribute to microbiological growth if carcasses are not properly spaced and adequately chilled.


Perhaps the most effective point in the process for an additional intervention is during the chilling process. There is ample time for an intervention since carcass chilling usually requires 24-48 hours. An effective intervention applied for a sufficient length of time may allow for the validated pasteurization of carcass surfaces. Hopefully, USDA’s focus on slaughter interventions and process control will accelerate the development of post-slaughter pasteurization technologies. If this can be achieved, the beef industry could finally claim victory over the problem of E. coli O157:H7.





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