Update your canning methods for safety

Many recommendations for canning methods have changed over the years. Home food preservers need to update their methods to keep food – and people – safe.

Three jars of canned white beans.
Photo: Karen Fifield.

Consider updating your canning recipes or methods to keep your family safe. Methods have been updated over the years to reflect important research to ensure safe canned foods. For instance, the once-recommended (before 1940) open-kettle method of canning — where food is heated in a kettle, jars were filled, a lid is placed on the jar and no further processing is done — is now considered unsafe.

Other “innovative” methods you might read about on the internet but should never use to preserve foods include using the microwave, an electric oven, slow cooker, dishwasher, canning powders as preservatives or even the sun to process canned foods. These processes are extremely dangerous and can allow bacteria to grow in your jars. This is especially true of low-acid foods, which include all vegetables, meats, poultry, seafood, soups and mixed canned foods.

Improperly canned low-acid foods can contain the toxin that causes botulism without showing any signs of spoilage. Do not consume any low-acid food that you suspect has been improperly canned. Low-acid foods are considered improperly canned if any of the following are true:

  • The food was not processed in a pressure canner.
  • The gauge of the canner was inaccurate. (Have the gauge tested yearly to be sure it is accurate.)
  • Up-to-date researched processing times and pressures were not used for the size of the jar, style of pack and kind of food being processed.
  • Ingredients were added that were not in an approved recipe.
  • Proportions of ingredients were changed from the original approved recipe.
  • The processing time and pressure were not correct for the altitude at which the food was canned.
  • Low-acid foods would be considered to be improperly canned if it was canned in an electric pressure cooker.

Be especially aware of safe processing methods when it comes to vulnerable populations, older adults, young children and those with a compromised immune system or who are pregnant. These populations may be more susceptible to foodborne illness.

Steam canning was considered unsafe for many years. In recent years, testing has been conducted and it is considered safe when canning high acid foods. Before using a steam canner, it is important to know the elevation of your location so you can correctly calculate processing times. Also, it is not recommended to use a steam canner for items that may need a longer than 45 minutes for processing. For complete instructions on using a steam canner, follow instructions on National Center for Home Food Preservation website. Guidance can also be found on the Michigan Fresh factsheet, Basics of Steam Canning.

Now is a good time to update your recipes and instructions. Michigan State University Extension recommends using recipes from the National Center for Home Food Preservation website, the book So-Easy-to-Preserve (6th edition), the most current Ball Blue Book (37th Edition). To have your dial gauge canner tested, call your local Extension office for information. To find your elevation so you can correctly process food, you can visit the USGS website.  

Consequently, to keep your family and friends safe, keep your knowledge up to date. For more information on keeping your food safe, visit MSU Extension’s Safe Food and Water website, or check out Michigan Fresh's Food Preservation factsheets.

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