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College of Food, Agricultural, and Environmental Sciences


Chow Line: Using slow cookers for roasts debatable (for 4/1/06)

March 24, 2006

My husband does most of the cooking in our house. However, he sometimes cooks large roasts in our slow cooker. I have to wonder if that's a safe method. What do you think?

That’s a bit of a controversial question. Even though most slow cooker cookbooks carry recipes for roasts, cooking large cuts of meat in slow cookers is not recommended by the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS).

The concern is that large cuts of meat, such as roasts or whole chickens, could stay in the "danger zone" between 40 and 140 degrees Fahrenheit for too long. That potentially could allow food-borne disease-causing bacteria to multiply to substantial numbers.

Even after the food reaches higher temperatures, which kills the bacteria itself, you still may not be in the clear. Some types of bacteria, such as E. coli O157:H7 and Staphylococcus aureus, produce toxins that can remain in the food even after the bacteria itself is killed. Cooking may destroy the bacteria itself, but toxins are heat stable and may not be killed by cooking. The longer food stays in the danger zone, the more bacteria multiply and the more toxin could be produced.

Some people get around this by searing the roast -- browning it in a hot pan -- before they put it in their slow cooker. This doesn't offer 100 percent protection. But it does kill any bacteria residing on the surface of the roast, which is where the vast majority of bacteria hang out anyway. Searing also browns the meat, and those browning reactions provide full, intense flavor. (Note: It's a myth that searing meat "seals in the juices." That notion was disproven in the 1930s, but some people still swear by it.)

Others cut large roasts into smaller chunks, allowing them to heat through -- and pass through the danger zone -- more quickly.

Unfortunately, there's no hard and fast formula from the FSIS about how small a cut of meat must be to be considered safe to cook in a slow cooker. The FSIS recommendations say to "Cut food into chunks or small pieces to ensure thorough cooking," but nowhere is there a guideline on how small those chunks should be. You just have to determine what you're most comfortable with.

For additional guidelines, see the FSIS Web site at and do a search for "slow cookers."

Chow Line is a service of Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH 43210-1044, or -30-

Editor: This column was reviewed by Jaime Foster, registered dietitian and Ohio State University Extension associate in the Department of Human Nutrition, College of Human Ecology.

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Martha Filipic
Jaime Foster