Translocation of Surface-Inoculated Escherichia coli O157:H7 into Beef Subprimals following Blade Tenderization

In phase I. beef subprimals were inoculated on the lean side with ca. 0.5 to 3.5 log CFU/g of a rifampin-resistant (rif(r)) cocktail of Escherichia coli O157:H7 and passed once. lean side up, through a mechanical blade tenderizer. Inoculated subprimals that were not tenderized served as controls. Ten core samples were removed from each subprimal and cut into Six consecutive segments: segments 1 to 4 comprised the top 4 cm and segments 5 and 6 the deepest 4 cm. Levels of E. coli O157:H7 recovered from segment 1 of control subprimals when inoculated with ca. 0.5. 1.5 2.5. or 3.5 log CFU/g were 0.6. 1.46, 2.5, and 3.19 log CFU/g, respectively. Following tenderization. pathogen levels recovered from segment 1 inoculated with 0.5 to 3.5 loo CFU/g were 0.22. 1.06, 2.04, and 2.7 log CFU/g, respectively. Levels recovered in segment 2 were 7- to 34-fold lower than levels recovered from segment I. Next, in phase II, the translocation of ca. 4 log CFU of the pathogen per P was assessed for lean-side-inoculated subprimals passed either once (LS) or twice (LD) through the tenderizer and for fat-side-inoculated subprimals passed either once (FS) or twice (FD) through the tenderizer. Levels in segment I for LS, LD, FS, and FD tenderized subprimals Were 3.63, 3.52, 2.85, and 3.55 log CFU/g respectively. The levels recovered in segment 2 were 14- to 50-fold lower than levels recovered in segment 1 for LS. LD, FS, and FD subprimals. Thus. blade tenderization transfers E. coli O157:H7 primarily into the topmost I cm. but also into the deeper tissues of beef subprimals.