Carry E. coli
"We know E. coli 0157:H7 can be carried by
deer," said University of Georgia food scientist Mike
Doyle. "We don't know yet how prevalent it is in the
deer population. But we know they carry it."
Doyle, a microbiologist with the UGA College of Agricultural and
Environmental Sciences, is director of the Center for Food Safety
in Griffin, Ga.
Outbreak Traced to Venison Jerky
He and other scientists published a report on E. coli in venison in the April 16, 1997, Journal of the American Medical Association. The report traced a 1995 Oregon outbreak of E. coli-related illnesses to jerky made from venison.
The study showed clearly, he said, that deer meat can become contaminated with E. coli. It showed, too, that the popular practice of making venison jerky isn't always safe.
Home Dehydrators Don't Get Hot Enough
To kill the E. coli 0157:H7 bacteria, Doyle said, meat must be heated to 160 degrees. "The home dehydrators we've tested don't even come close to that," he said.
Judy Harrison, an Extension Service food scientist with the UGA College of Family and Consumer Sciences, said many home dehydrators don't have adjustable temperature controls.
"Many are preset at the factory, usually at 130 to 140 degrees," she said. "Even those that can be adjusted usually can't be set that high."
The safety problem with jerky, she said, is complicated.
Too Much Heat = Hard Meat
"If you dehydrate meat at too high a temperature, you can have something called 'case hardening,'" she said. "That's when the outside of the meat forms a crust. When that happens, the moisture inside can't get out, and the jerky will spoil."
Doyle said the only safe way to prepare jerky is to precook it to 160 degrees.
But when you do that, Harrison said, most jerky lovers don't like it. "We haven't done a formal taste-panel study yet," she said. "But the consensus among jerky connoisseurs seems to be that it's not acceptable, or at least not what they're used to."
The Safe Way to Make Jerky
Harrison, CAES microbiologist Mark Harrison and Oregon State University scientist Carolyn Raab have been studying the jerky riddle.
"We've been trying to find a method to prepare jerky that can eliminate pathogens and still produce a product similar to the traditional jerky people like," she said. "So far, we haven't been able to do that. But we will continue to look at other options."
People who make jerky do it two main ways, she said. Some dry strips of meat. Others start by grinding the meat. "Then they use a gizmo like a cookie press," she said, "that squeezes out a ribbon of meat."
The dehydrated ribbons have a texture many people like, she said. But because it's ground meat, the contamination risk is higher.
The risk is always higher with ground meat, Doyle said. Many deer hunters have at least part of their meat prepared as ground venison or sausage.
Roasts are Safer Than Ground Meat
"With a roast, if the organism is there, it's on the surface and is more easily killed," Doyle said. "With ground meat, the organism can be in the very center."
Anyone making a fermented sausage with venison, he said, must make sure to do it by U.S. Department of Agriculture guidelines for making sausage containing beef.
"You have to have a step in the process that will kill 100,000 E. coli 0157:H7 bacteria," he said. "It's not like it used to be. You can't just let it naturally ferment."
(Article by Dan Rahn, University of Georgia College of Agricultural and Environmental Sciences. Deer photograph by Scott Bauer, USDA. )
Oct. 20, 1997