Translocation and cross-contamination of E. coli O157 in beef eye-of-round subprimal cuts processed with high-pressure needleless injection.

UNLABELLED: High-pressure needleless injection (HPNI) is an emerging enhancing process where small-diameter, high-velocity bursts of liquid penetrate soft foods at pressures up to 69 MPa. The incidence and depth of translocated surface-inoculated E. coli O157 in HPNI-processed beef eye-of-round subprimal cuts was determined. HPNI translocated E. coli O157 from the surface to the interior of the eye-of-round subprimal cuts with incidence of 40% (± 7%), 25% (± 8%), and 25% (± 8)% for subprimals that had been surface-inoculated with a 4-strain cocktail at 0.5, 1, and 2 log₁₀ CFU/cm² , respectively. The run-off water was collected and found to contain 2, 2, and 3 log₁₀ CFU/mL E. coli O157. The runoff was reused for HPNI of additional subprimals, and this resulted in a cross-contamination incidence of 83% (± 4%), 60% (± 15%), and 37% (± 6)%. Incidence of translocation and cross-contamination was similar at 0 to 1, 1 to 2, 2 to 3, 3 to 4, 4 to 6, and 6 to 8 cm below the inoculated surface. Results indicate that surface microbiota on beef will be carried to the interior of HPNI-processed beef by initial translocation from the surface with the injected fluid and by cross-contamination with recycled fluid.

PRACTICAL APPLICATION: This research has practical relevance for the beef enhancement process called high-pressure needleless injection. The process's effect on surface bacteria on beef was studied.