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Using electric pressure cookers for canning doesn't destroy botulism bacteria, study says

PROVO — Cathy Merrill likes preserving food through canning.

Although it’s a tedious process at times, she enjoys having the food ready on her kitchen shelves.

It’s why Merrill, an assistant professor for family and consumer sciences at the Utah State University extension office in Utah County, said she wanted to make sure canning was done safely — and she found what she believed she might find: Using electric pressure cookers for small batch, low-acid canning may not destroy bacteria that causes botulism.

A previous study from the researchers found altitude affects the temperatures in electric pressure cookers; however, the USU Extension study, which was released on Friday, found that during the canning process electric pressure cookers like Instant Pot and Power Pressure Cooker XL didn’t kill that bacteria in foods like vegetables, beans, meats, poultry, fish or soups no matter the altitude.

Companies had advertised their products as safe items to can with, Merrill said. So the researchers put it to the test.

They used three pressure cookers and filled them with different density food substances and then went to St. George, Monticello and Provo — all three different altitudes.

“We tracked the temperature rise and fall and got all of the data on it,” she said. “There is a temperature that it’s supposed to get to for 'X' amount of time in order to kill Clostridium botulinum spores. If those spores are not killed, and if you’ve canned something that’s low-acid, when you put them on the shelf, if it has spores in it, they can open up and create this botulism toxin, which is deadly.”

It didn’t matter if the elevation was at 2,500 feet or 7,000 feet, researchers weren’t able to reach 250 degrees Fahrenheit, which is the temperature needed to kill the bacteria, Merrill added. She said other researchers at the University of Georgia found the same thing at lower elevations than Utah.

For people who want to go into canning, Merrill said high-acid canning isn’t as much of a problem; or you can get a stovetop pressure canner to reach the right temperature.

Merrill said researchers hope to conduct further studies on the matter, along with Georgia researchers. The university extension has a 25-hour course on pressure cooking planned for June, as well.

“We don’t want anyone dying from botulism,” Merrill said. “We’re not trying to make life hard for anybody, we’re trying to make it safe so people can safely feed their families.”

For more information please visit the USU Extension Page