Project Summary

Salmonella spp. and Listeria Monocytogenes Risk Assessment for Production and Cooking of Blade Tenderized Beef Steaks

Principle Investigator(s):
James L. Marsden, Randall K. Phebus, Harshavardhan Thippareddi, Curtis L. Kastner and James B. Gosch
Kansas State University
Completion Date:
June 2001  


Layman’s Summary

Results show that there is no difference in risks between intact (non-tenderized) and non- intact (tenderized) steaks at cooking temperatures ranging from rare (130°F) to well done (170°F) for Salmonella spp. However, differences in Listeria monocytogenes reductions between steaks obtained from tenderized and non-tenderized subprimals were observed on cooking to target temperatures of up to 160°F, and not 170°F. Sporing (1999) recommended a target endpoint temperature of ≥140°F for cooking both tenderized and non-tenderized steaks based on extensive studies with E. coli O157:H7 to reduce the risk of this pathogen in steaks obtained from tenderized subprimals. The present study shows that same target temperature would reduce the risk of Salmonella spp. and L. monocytogenes in steaks obtained from blade tenderized subprimals. Baseline studies performed by USDA-FSIS indicate very low contamination levels of these pathogens on beef carcasses and concentrations of these pathogens would be even lower on cuts obtained from interior muscles such as those used for fabricating the steaks. Thus, both intact and non-intact steaks are safe for consumers, when cooked to the internal temperatures of rare to well-done using a commercial grill.

In this study, we intentionally inoculated beef cuts with high levels of Salmonella spp. and Listeria monocytogenes in order to quantify the effect of mechanical tenderization on the translocation of bacteria from the surface of the beef cuts into the interior of the muscle. The levels of contamination used do not reflect levels that are likely to be present. In actual practice, the source point of contamination for these pathogens is at the carcass level and contamination is prevented or reduced through application of numerous processing steps, including validated antimicrobial technologies and enforcement of USDA-FSIS’s zero tolerance policy for physical defects. The potential of contamination is further reduced by the removal of the carcass surface by trimming before mechanical tenderization.

A target internal temperature of 140°F appears to provide the necessary thermal destruction required to virtually eliminate Salmonella spp. and L. monocytogenes risk. By including validated antimicrobial intervention strategies in the slaughter and fabrication processes to improve initial microbial quality of products destined for blade tenderization, the likelihood of pathogenic contamination is further decreased, thus decreasing the level of process lethality required during cooking of tenderized cuts.