Food Preservation: Home Canning Safety

Many people discovered new hobbies during the pandemic.

Some learned to bake bread. Others took up knitting and crocheting. Still others found self-care in gardening and preserving the literal fruits—and vegetables—of their labors.

Food preservation is an excellent way to extend the shelf life of produce, meats, and seafood, and add to your emergency food supply. But it can be risky—or even deadly—if not done safely.

Why preserve food?

A lot of the foods we eat go bad quickly if not eaten right away. We can make these foods last longer when we properly preserve them.

You can preserve food in different ways. They include drying, curing, smoking, freezing, fermenting, pickling, and canning.

Learning how to preserve different types of food is a practical skill you can use to supplement your emergency food supply. Families should stock up on enough food and water to last everyone at least 3 days.

Home canning

Proper canning removes oxygen, destroys enzymes, and prevents the growth of undesirable bacteria, yeasts, and molds.(1) If you can foods incorrectly, you could create the perfect environment for deadly bacteria to grow and cause botulism.

Botulism is a rare but potentially deadly illness caused by a toxin produced by the bacteria Clostridium botulinum.(2)

Botulism is a medical emergency. If you or someone you know has symptoms of foodborne botulism, see your doctor or go to the emergency room immediately:(2)

• Difficulty swallowing
• Muscle weakness
• Double vision
• Drooping eyelids
• Blurry vision
• Slurred speech
• Difficulty breathing
• Difficulty moving the eyes

Many cases of foodborne botulism have happened after people ate home-canned, preserved, or fermented foods that were contaminated with the toxin. Foods can become contaminated if they were not canned using the correct techniques or tools.

USDA guidance suggests that beginners start with high-acid foods that can be safely canned in a boiling water bath, before trying pressure canning. Only use recipes from reputable sources. Contact your local cooperative extension service office with questions.

How to can safely

You can take steps to make sure your food is properly preserved. The USDA Complete Guide to Home Canning has step-by-step directions to prevent botulism and includes specific guidance for different kinds of foods. Regardless of canning techniques and tools, always consider the acidity of the food you are trying to preserve.

Canning techniques

Low-acid foods—including most vegetables, some fruits, milk, and all meats, fish, and seafood—are the most common sources of botulism linked to home-canning.

Low-acid foods are foods that are not acidic enough to prevent the growth of botulinum bacteria. Pressure canning is the only recommended method for canning these foods.(2)

Pressure canning tools

Make sure to use the right equipment for the kind of foods you are canning, including the right-sized pressure canner.

The canner should be big enough to hold at least four one-quart jars sitting upright on the rack. It should also meet USDA recommendations for pressure canning when canning low-acid foods. Be sure the gauge of the pressure canner is accurate.

After using a pressure canner, check that your cans are properly sealed in one of these three ways:

1. Press the middle of the lid with your finger or thumb to see that the lid does not spring up.
2. Tap the lid with the bottom of a spoon to make sure it does not make a dull noise (it should make ringing sound).
3. Hold the jar at eye level to see that the lid is curved down slightly in the center.(1)

If you have any doubt whether safe canning guidelines were followed, do not eat the food. When in doubt, throw it out!

Storage & maintenance of canned goods

Store your home canned goods properly to maximize their shelf life.

• Label and date your jars.
• Keep jars with other emergency food in a clean, cool, dark, dry place between 50 and 70°F. (1) If you store jars at temperatures outside this range, the food inside can spoil.
  • Stack jars no more than two high so you don’t damage the seals.
  • If storing jars where they can freeze, wrap them in newspapers and blankets.(1)
• Remove, throw away or use, and replace any canned food and stored water before it expires.
  • Home-canned food usually needs to be thrown out after a year.
  • Remember that once a can is opened, the contents cannot be saved until later without proper refrigeration.
  • When storing safe water, it is best to use food-grade storage containers and to clean and sanitize the container before using it. Replace stored water every six months.

For more information on how to can safely, visit the USDA Complete Guide to Home Canning.

Resources

• CDC Home Canning and Botulism
• National Center for Home Food Preservation

References

1. https://nchfp.uga.edu/how/general/how_canning_preserves_foods.html
2. https://www.cdc.gov/foodsafety/communication/home-canning-and-botulism.html