How to avoid botulism when canning food

Follow science-based canning methods to avoid the growth of germs that can cause botulism.

The trend to preserve food at home appears to be growing, so the importance of up-to-date processes to preserve food also grows to help keep people from becoming sick. Did you know that if food is incorrectly processed there is the potential for bacteria that can cause botulism to grow in your jars? It’s a scary thought, but the potential is there when guidelines for safe food preservation are not followed.

Botulism is caused by bacteria called Clostridium botulinum that is found in our soil and it has the potential to survive the canning process if the item is not correctly processed. This bacteria cannot be seen, smelled or tasted, and so becomes a silent killer if we are not careful. The Centers for Disease Control and Prevention (CDC) emphasize strongly the need to consider the experience of any symptoms of botulism as a medical emergency. 

Symptoms of botulism:

  • Double or blurred vision
  • Drooping eyelids
  • Slurred speech
  • Swallowing issues
  • Thick tongue
  • Dry mouth
  • Muscle weakness                                                                                       

If you experience any of these symptoms, you must seek medical assistance.

A safe reference to use as a home canning guide is the United States Department of Agriculture (USDA) website on proper canning methods. When deciding which canning method should be used, remember that low-acid foods such as vegetables, meats, some tomatoes and fish need to be properly canned in a pressure canner for the designated amount of time indicated in the USDA recipe. You can locate various recipes in the USDA Complete Guide to Home Canning. These recipes are science-based and should be followed as written.

When storing home-canned goods, there are also rules that should be followed. Let the canned goods set and cool for at least 12-24 hours before disturbing. This will help ensure the lid has sealed correctly and completely. The lid should have a dip in the center when it has cooled and sealed. Store jars without the ring. Metal to metal can rust and even a pinhole of air can enable bacteria to grow. If there is any botulism in the jar, it can make you very sick or even lead to death. Label and date each jar, and use the oldest first. Home-canned goods are best if used within one year.

Michigan State University Extension suggests contacting your local MSU Extension office for more information about classes offered in your area. 

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