Food Safety News

Escherichia coli O157:H7 in Mechanically Tenderized Beef Prime Rib

Campus Administrator
Escherichia coli O157:H7 in Mechanically Tenderized Beef Prime Rib
by Campus Administrator - Monday, 25 March 2013, 5:10 PM


We evaluated the effect of commercial times and temperatures for searing, cooking, and holding on the destruction of Escherichia coli O157:H7 (ECOH) within mechanically tenderized prime rib.

Boneless beef ribeye was inoculated on the fat side with ca. 5.7 log CFU/g of a five-strain cocktail of ECOH and then passed once through a mechanical tenderizer with the fat side facing upward. The inoculated and tenderized prime rib was seared by broiling at 260°C for 15 min in a conventional oven and then cooked in a commercial convection oven at 121.1°C to internal temperatures of 37.8, 48.9, 60.0, and 71.1°C before being placed in a commercial holding oven maintained at 60.0°C for up to 8 h. After searing, ECOH levels decreased by ca. 1.0 log CFU/g. Following cooking to internal temperatures of 37.8 to 71.1°C, pathogen levels decreased by an additional ca. 2.7 to 4.0 log CFU/g. After cooking to 37.8, 48.9, or 60.0°C and then warm holding at 60.0°C for 2 h, pathogen levels increased by ca. 0.2 to 0.7 log CFU/g. However, for prime rib cooked to 37.8°C, pathogen levels remained relatively unchanged over the next 6 h of warm holding, whereas for those cooked to 48.9 or 60.0°C pathogen levels decreased by ca. 0.3 to 0.7 log CFU/g over the next 6 h of warm holding. In contrast, after cooking prime rib to 71.1°C and holding for up to 8 h at 60.0°C, ECOH levels decreased by an additional ca. 0.5 log CFU/g.

Our results demonstrated that to achieve a 5.0-log reduction of ECOH in blade tenderized prime rib, it would be necessary to sear at 260°C for 15 min, cook prime rib to internal temperatures of 48.9, 60.0, or 71.1°C, and then hold at 60.0°C for at least 8 h.