Safe Pressure Canning

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• 5 Tips For Ensuring That You Can Food Safely

  Canning food is a popular Wisconsin pastime, and also also a risky one: If done incorrectly, the food that’s being preserved could become infected with the toxin that causes botulism.

  Here are some tips from Barbara Ingham, a professor of food science at University of Wisconsin-Madison and food safety specialist with UW-Extension, on how to do canning safely:

  1. Take note of a food’s acidity.

  Canning food using a boiling water bath is generally safe with high-acid foods, said Ingham. That acidity in foods like jams, pickles, relishes and salsas creates an inhospitable environment for the bacteria that produce botulism-causing toxins.

  With lower-acid foods that could potentially become contaminated, such as meats and vegetables, don’t risk a boiling water bath. In such cases, pressure canning is the safest way to proceed.

  2. Check whether you have a pressure cooker or pressure canner.

  Pressure cookers are designed for the quick and easy cooking of food for a meal. It’s possible to use them for canning high-acid foods, but since they cool down and heat up quickly and may not be able to adequately regulate pressure, there’s no guarantee they’d be able to eliminate microorganisms in the same way a pressure canner would. Therefore, with low-acid foods, opt for the canner.

  3. Get a dial gauge canner tested and recalibrated.

  While some canners just have three pressure settings (5, 10 or 15 pounds if it’s a weighted gauge canner, according to Ingham), others have a dial for selecting the desired pressure. Ingham said that this type of canner, known as a dial gauge canner, should be tested each year at the start of the canning season, and that the dial should be recalibrated as well. She said that many UW-Extension offices around the state offer that service.

  “It’s a quick test to make sure that you’re canning safely,” she said.

  4. Give a canner a trial run.

  Ensuring that gaskets and other parts of the sealing mechanism are working properly is another important step. Ingham said that one way to do this is to just can some water before starting on items that are for consumption. That test of the machinery is a good way to ensure safety.

  (More information on getting a pressure canner ready for the season is also available in this Cooperative Extension article.)

  5. Use approved and up-to-date recipes.

  Recipes for simple cooking don’t necessarily change much over the years, but pressure canning recipes do, said Ingham.

  “The recipes have changed dramatically,” she said. “If I look at a 1904 or 1906 Ball Blue Book, where pressure canners weren’t something that people had, they might be water-bath canning green beans, which we know now is unsafe and we don’t do that anymore.”

  Ingham recommended finding up-to-date recipes using a trusted source, such as the UW Extension itself and its food preservation website. By starting with a good recipe and using the right equipment, “it’ll be worthwhile,” she said. “All the time that you’ve invested and that wonderful garden produce will be not only delicious but safe (for) your family.”