Intervention Practices

The hides of cattle are the primary source of pathogens which may cause contamination of beef carcasses; therefore, effective decontamination of the hide results in less contamination of the carcass following hide removal. The best evidence for the effectiveness of hide intervention is chemical dehairing. Many antimicrobial compounds such as cetylpyridinium chloride (CPC), sodium hydroxide, trisodium phosphate, chlorofoam, phosphoric acid and vacuuming have been evaluated for their efficacy as hide interventions. Each chemical intervention usually followed by a rinse step using either water or acidified chlorine. Most regimes were found effective in reducing hide contamination to some level. Vacuuming of the treated areas to remove excess liquid further improved hide cleanliness. Ozonated water and electrolyzed oxidizing (EO) water, both possess strong oxidation–reduction potential, have also been evaluated to determine their efficacy as potential hide interventions. 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.

Once the hide has been removed from the beef carcass, numerous interventions follow. The most commonly applied is knife trimming of visibly contaminated carcass regions (i.e. hide removal pattern lines). Steam vacuuming is an alternative to knife trimming that effectively removes visible contamination without product loss. Steam vacuuming has been implemented in nearly all beef processing plants at multiple stages in the slaughter operations. In the processing plant, knife trimming and steam vacuuming can produce bacterial reductions in localized areas. These techniques, however, cannot be used efficiently for the entire carcass. Therefore, other interventions such as organic acids and hot water are used for carcass spray washing.

One intervention step sometimes may not be sufficient and “multiple hurdle” carcass interventions are used at various processing steps to ensure the safety of beef products. For example, steam vacuuming that achieves significant reduction of bacteria on beef is followed with a pre-evisceration wash of hot water or organic acid. After evisceration and splitting, carcasses pass through a thermal pasteurization chamber, where heated water or steam is applied. This treatment is lethal to bacteria on the carcass surface and further cleanses the carcass. Finally, an organic acid or chlorine rinse is applied before carcasses enter the holding cooler.