Steak! Researchers give it a grilling.
Escherichia coli (Research)
|Publication:||Name: Agricultural Research Publisher: U.S. Government Printing Office Audience: Academic; General Format: Magazine/Journal Subject: Agricultural industry; Biotechnology industry; Business Copyright: COPYRIGHT 2011 U.S. Government Printing Office ISSN: 0002-161X|
|Issue:||Date: April, 2011 Source Volume: 59 Source Issue: 4|
|Topic:||Event Code: 310 Science & research|
|Organization:||Government Agency: United States. Agricultural Research Service|
|Geographic:||Geographic Scope: United States Geographic Code: 1USA United States|
Steak is an ail-American favorite. To help make sure that E. coli
0157:H7 and some of its Shiga-toxin-producing relatives will not ruin
the pleasure of this popular entree, ARS researchers have tested the
effects of grilling on these microorganisms.
In particular, they're learning more about the movement of E. coli into "subprimals," the meat from which top sirloin steaks are carved. Their focus is on what happens to the E. co//'when subprimals are punctured, as part of being tenderized, and the effect of gas-grill cooking on survival of those microbes. The concern is whether tenderizing processes move significant amounts of E. coli cells into the deep interior tissues of the meat, says microbiologist John B. Luchansky with ARS's Eastern Regional Research Center in Wyndmoor, Pennsylvania.
In the study, scientists applied various levels of E. coli 0157:H7 to the lean surface of subprimals, ran the meat (lean side up) through a blade tenderizer, then took core samples from 10 sites on each subprimal, to a depth of about 8 centimeters. In general, only 3 to 4 percent of the E. coli 0157:H7 cells were transported to the geometric center of the meat, they found. At least 40 percent of the cells remained in the top 1 centimeter. "Knowing where a pathogen is most likely located--in or on steaks-is the first step toward validating proper cooking methods and temperatures for killing it," Luchansky says.
To learn more about the effects of grilling, the group examined other subprimals, applying E. coli 0157:H7 to the lean surface, running the subprimals once through the blade tenderizer (lean side up), then slicing the meat into steaks either 3/4-inch, 1-inch, or 1 1/4-inch thick. Using a commercial open-flame gas grill they cooked the steaks-on both sides-to an internal temperature of 120T (very rare), 130[degrees]F (rare), or 140[degrees]F (medium rare).
"Our findings confirm that if a relatively low level of E. coli 0157:H7 were to in fact be distributed throughout a blade-tenderized top sirloin steak, proper cooking on a commercial gas grill is effective for eliminating it," Luchansky says.
He did the work with Wyndmoor colleagues Jeffrey E. Call, Bradley Shoyer, and Anna C.S. Porto-Fett; Randall K. Phebus of Kansas State University; and Harshavardhan Thipparredi of the University of Nebraska. Articles published in the Journal of Food Protection in 2008 and 2009 document these preliminary findings.
This research was funded by the Beef Checkoff and the USDA Food Safety and Inspection Service as well as ARS.--By Marcia Wood, ARS. *
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