Thermal inactivation of Escherichia coli 0157:H7 (ECOH) and non-0157 Shiga toxin-producing E.coli (STEC)in mechanically tenderized veal

Authors: Luchansky, John; Porto-Fett, Anna; Shoyer, Brad; THIPPAREDDI, HARSHAVARDHAN - University Of Nebraska; AMAYA, JESUS - Nagle Veal, Inc; LEMLER, MICHAEL - Nagle Veal, Inc

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2014
Publication Date: 6/1/2014
Publication URL: https://handle.nal.usda.gov/10113/59692
Citation: Luchansky, J.B., Porto Fett, A.C., Shoyer, B.A., Thippareddi, H., Amaya, J., Lemler, M. 2014. Thermal inactivation of Escherichia coli 0157:H7 (ECOH) and non-0157 Shiga toxin-producing E.coli (STEC)in mechanically tenderized veal. Journal of Food Protection. 77:1201-1206.

Interpretive Summary: United States Department of Agriculture, Food Safety and Inspection Service (USDA-FSIS) verifies that establishments control relevant physical and microbial hazards in regulated meat, poultry, and processed egg products. In 2012, USDA-FSIS began verification testing for non-O157 STEC in domestic and imported beef manufacturing trimmings from cattle slaughtered on or after June 4, 2012. FSIS verification sampling results to date suggests that the percent positive for STEC is higher from veal products than from beef products. More specifically, data provided by USDA-FSIS as part of their testing of raw ground beef component (RGBC) samples in Federal plants as of July 14, 2013, establish the percent positive for Shiga toxin-producing Escherichia coli O157:H7 (ECOH) and Shiga toxin-producing non-O157 E. coli (STEC) cells in beef at 0 and 0.78% (3/383), respectively, whereas the percent positive for ECOH and STEC in veal are 6.12% (3/49) and 7.69% (1/13), respectively. These findings raise the questions as to what are the most significant processing risk factors, as well as retail, food service, and consumer public health risk factors, for STEC associated with veal. To this end, we validated the effect of mechanical tenderization and cooking of veal cutlets on the comparative translocation and thermal inactivation of ECOH and STEC. Our findings confirmed that typical consumer practices of cooking blade tenderized veal cutlets in about 15 ml of cooking oil for about 2.25 minutes per side at the recommended internal temperature of 71.1 deg C was sufficient to eliminate at least 100,000 cells of pathogenic and Shiga toxin-producing E. coli.

Technical Abstract: We quantified thermal destruction of Shiga toxin-producing Escherichia coli O157:H7 (ECOH) and Shiga toxin-producing non-O157 E. coli (STEC) cells within mechanically tenderized veal cutlets following cooking on an electric skillet. For each of five trials, flattened veal cutlets (ca. 71.6 g; ca. 1/8 inch thick) were surface inoculated with ca. 6.8 log CFU/g of multi-strain cocktails of ECOH or STEC and mechanically tenderized by passing once through a “Sir Steak” tenderizer. For each cooking time, in each trial, three inoculated and tenderized cutlets were individually cooked for 0.75, 1.0, 1.25, 1.5, or 2.25 min per side on a skillet set at 191.5 deg C. Canola oil (ca. 15 ml) was added onto the skillet prior to cooking, and the temperatures of the meat and of the skillet were monitored and recorded using a Type J thermocouple. With longer cooking times, a higher internal temperature of the meat was achieved, along with a greater reduction of both ECOH and STEC. The mean final internal temperature of the meat ranged from 60.5 to 89.2 deg C. Microbial reductions of ca. 1.9 to 6.3 log CFU/g and ca. 2.7 to 6.1 log CFU/g were achieved for ECOH and STEC, respectively. To deliver a 5.0-log reduction of ECOH or STEC, and to achieve the recommended internal temperature of 71.1 deg C, it was necessary to cook mechanically tenderized veal cutlets on a pre-heated electric skillet set at ca. 191.5 deg C and containing 15 ml of cooking oil for at least 2.25 min per side. These data established that cooking times/temperatures effective for inactivating serotype O157:H7 strains of E. coli in ground beef are equally effective against the additional six Shiga toxin-producing strains investigated herein.