Additional <I>E. coli</I> Interventions Should Focus on Post Chill Carcasses

Since 2006, USDA reported a significant increase in the incidence of E. coli O157:H7 in ground beef. In addition, the public health improvements associated with beef-related E. coli O157:H7 cases and outbreaks that were so apparent in 2002-2005 were reversed.

There are many theories for the reemergence of the E. coli O157:H7 problem in the beef industry. These include changes in animal feeding practices, an influx of unskilled workers in slaughter plants, climate changes, and increasingly resistant strains of E. coli O157:H7.

Regardless of the causes, the beef industry is challenged again to solve the problem of E. coli O157:H7. Over the past several years, beef slaughter plants implemented effective interventions and improved sanitary conditions. Beef carcasses are visually clean and, for the most part, microbiologically improved.

However, there is room for further improvement.

The beef slaughter and chilling processes provide the best strategic opportunity for control of E. coli O157:H7 contamination. At this point in the process, microbiological contamination is limited to the outside carcass surface, and therefore it can be eliminated most readily.

The ideal beef slaughter process would employ a series of interventions, including chemical antimicrobial treatments, thermal pasteurization, and steam vacuuming (for removal of physical defects).

The slaughter process would be designed to assure that the hide removal and evisceration processes do not result in carcass contamination, and that the slaughter environment does not facilitate contamination via particles or aerosols. The ideal carcass cooling process would assure that carcasses are well spaced and chilled uniformly.

Unfortunately, these conditions do not always exist.

In order to correct for possible deficiencies in the slaughter and/or cooling processes, an additional intervention is needed. An effective post chill antimicrobial treatment could potentially eliminate pathogen contamination on carcass surfaces.

An intervention at this point could also act as a barrier between the slaughter process which is inherently difficult to control and post-slaughter fabrication and processing environments which can be effectively managed.

Interventions which would act as post-chill carcass pasteurization steps are under development. Technologies under consideration include carcass irradiation (as a processing aid) and antimicrobial gases.

The implementation of an effective intervention at this strategic point in the process may be the piece that has been missing in solving the E. coli O157:H7 problem in the beef industry.

Marsden is NAMP senior science advisor and regent’s distinguished professor for food safety & security, Kansas State University.