Project Summary

Evaluation of Interventions to Reduce Microbial Contamination in the Manufacture of Blade Tenderized Beef

Principle Investigator(s):
James E. (Ken) Kennedy and William L. Brown
ABC Research Corporation
Completion Date:
May 2003



In 1999 a survey was completed that determined the types and levels of pathogens in non-intact beef products. The information obtained in this survey indicated the need for further investigation in this category of products and an additional study involving inoculated pilot plant work by NCBA was carried out at ABC Research to determine the effect of various cooking temperatures on certain pathogens in blade-tenderized steaks. The results of this study indicated occasional survival of pathogens, particularly when the product was inoculated with high concentrations of the pathogen and cooked to a lower internal temperature. A subsequent survey study was conducted for NCBA by ABC Research to determine the sources and extent of microbial contamination in the commercial manufacture of blade-tenderized beef products. Salmonella was not detected in any environmental or product samples in that study and the levels of Listeria monocytogenes detected were very low (i.e., 2.4 and 2.8% of 520 product surface and 281 environmental samples, respectively). Furthermore, there was no evidence of transfer of naturally contaminating pathogens from the surface to the interior of blade-tenderized products. Internalization of aerobic plate counts and Enterobacteriaceae to the product interior by blade tenderization was only observed with high microbial loads on subprimal surfaces. Although the internalization rate could not be quantified in that study, a comparison of microbial contamination levels on the surface vs. the internal portions of tenderized subprimals suggested that the internalization rate of surface microbial contamination might be lower than previously believed. The results of that study also indicate that the primary source of the microbial contamination is the surface of the incoming subprimals and that the most effective intervention strategy to control the introduction of pathogens into the internal portion of these products would be to apply an intervention to the surface of the subprimals before they are subjected to blade tenderization. This type of intervention strategy combined with appropriate cleaning and/or sanitizing of the blade tenderizer and associated pre-tenderizer equipment should result in a significant reduction in the levels of pathogens on the surface of the subprimals and the blade tenderizing equipment. This, in turn, should result in a much reduced risk for introduction of pathogens into the interior of these products.

The stated objectives for this work were:

  • In a pilot plant setting, to develop and evaluate a prototype intervention method for application to subprimals prior to blade tenderization, to identify a naturally occurring indicator or surrogate organism for E. coli O157:H7 that can be used to validate intervention treatments under commercial plant conditions, to develop a method to quantify the internalization rate of bacteria from the surface to the interior of subprimals via blade tenderization, and to quantify the rate of bacterial internalization.
  • In a commercial plant setting, to evaluate the efficacy of one intervention method on the reduction of microbial contamination of blade tenderized beef subprimals, to evaluate the effect of tenderizer equipment sanitation on the intervention efficacy and to quantify the rate of bacterial internalization.

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