Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/11/2010
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Introduction: Previous studies have shown that chemical or mechanical tenderization transfers Escherichia coli O157:H7 (ECOH) and non-O157:H7 verocytotoxigenic E. coli (STEC) throughout the interior of beef subprimals. Purpose: Evaluate the viability of ECOH or STEC in brine-injected beef subprimals during storage and subsequent cooking on a commercial open-flame gas grill. Methods: Beef subprimals were inoculated on the lean side with ca. 5.7 log CFU/g of a five-strain cocktail of rifampicin resistant ECOH strains or kanamicin resistant STEC strains and then passed once through an automatic brine-injector tenderizer with the lean side facing upwards. Brine solutions were formulated with: i) 3.3% (w/v) of sodium tripolyphosphate and 3.3% (w/v) of sodium chloride or ii) 3.3% of sodium tripolyphosphate, 3.3% (w/v) of sodium chloride, and 25% (v/v) of a 60% potassium lactate-sodium diacetate syrup. The brine was injected into subprimals to a target level of 9.1 +/- 0.8% over fresh weight. Following injection, subprimals were cut into 2.54 cm (1 inch) thick steaks and then stored for up to 15 days at 4C. Brine-injected steaks were cooked on a commercial open-flame gas grill to internal endpoint temperatures of either 37.8C (100F), 48.8C (120F), 60C (140F), or 71.1C (160F). Results: Regardless of brine formulation, storage of brine-injected steaks for up to 15 days at 4C resulted in a 0.3- to 1.4-log CFU/g reduction of ECOH and STEC. Regardless of storage time, brine formulation, or cooking temperature, cooking achieved log CFU/g reductions of 1.1 to 4.8 of ECOH and 1.5 to 4.3 of STEC. At 71.1C (160F) the percent of organisms recovered ranged from 0.0013% to 4.0% for ECOH and from 0.0034% to 0.12% for STEC. Significance: Cooking highly contaminated, brine injected steaks on a commercial gas grill to 71.1C (160F) is insufficient to kill all cells of ECOH and STEC.