How to safely can food: 4 tips for home food preservation

canned tomato sauce

Canning season is right around the corner. Whether you use a water bath canner for jams and jellies or a pressure canner for garden vegetables, there are precautions you should take in order to safely can food for your family and friends.

1. Only use recommended jars, lids and canners

The National Center for Home Food Preservation warns about the dangers of using improper tools for home canning.

It is recommended that metal or glass jars be used for canning. Mason-style jars are best suited for canning. There are a number of brands, like Ball, Kerr and store brands that are designed for canning.

Glass jars can be reused, while metal cannot. Self-sealing lids must be used for home canning, as well as threaded screw bands. Lids cannot be reused, but screw bands can be reused as long as they aren’t dented, bent or rusted.

Used commercial food jars that once held mayonnaise, pickles or something else may crack during pressure canning or the seals may break, causing the food to spoil. Although these jars may seal properly, the seals are more likely to fail and the jars are more susceptible to breakage.

If you’re reusing jars, inspect them before canning. Make sure that there aren’t any cracks. If you’ve used the same jars over and over again, they will be weaker and may not seal properly.

2. Test your canner

If your pressure canner is brand new or if you just got it out for the first time this season, test it to make sure it’s working properly. Clemson University Cooperative Extension advises testing several parts of your pressure canner before using it.

  • Make sure that the rubber gaskets are soft and flexible, if your pressure canner has them.
  • Also, make sure that all vents and openings are clean and clear.
  • The lid must fit properly and lock into place. It can’t be warped.
  • Finally, your pressure canner’s dial should be tested for accuracy every year. Learn how to do this by contacting your local hardware store or your local Extension office.

You should also test your pressure canner before using it.

  • Put several inches of water in your canner, then secure the lid and seal the vent.
  • Turn on the heat and monitor the canner’s pressure.
  • Make sure that it reaches the needed pressure and maintains it without leaking.
  • Lastly, practice depressurizing the canner correctly and remove the lid.

3. Only can the best produce

The National Center for Home Food Preservation recommends canning good-quality fresh foods. Don’t can diseased or moldy foods. Cut off any small diseased spots on food before canning.

When you’re canning tomatoes, be choosy. Don’t pick ones that are overripe, damaged, decayed, exposed to frost, harvested from dead or frost-killed vines or late-season fruits grown indoors. These may not be safe for canning since they may be lower in acidity than tomatoes grown on vines in the garden, according to Minnesota State University Extension. Use these tomatoes for fresh eating, freezing or cooking instead.

4. Use the right type of canner

A pressure canner should be used to can low-acid vegetables, meats, fish and poultry. Water bath canning or boiling water canning does not get hot enough to kill bacteria in low-acid foods. Spores of the bacteria Clostridium botulinum are heat resistant and found naturally in soil. Even if vegetables have been in a boiling water canner for hours, they will survive and will germinate into active cells that will cause deadly food poisoning, according to the National Center for Home Food Preservation.

For information about pressure canning times, see the University of Minnesota Extension’s reference chart for pressure canning.

A water bath or boiling water canner should be used for canning jams, jellies, fruits and pickles. There should be enough room that an inch or two of water can boil on top of the jars. Also, there needs to be a rack at the bottom of the canner for jars to sit on.

For more information about food acidity and processing methods, refer to the National Center for Home Food Preservation’s website.

More tips

For more tips on safely preserving food at home, see the National Center for Home Food Preservation’s website and Minnesota State University Extension’s Canning page.

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  1. I definitely agree with the idea of testing out a canner before putting it to heavy use. One little error that goes unnoticed can be pretty serious. The fourth section provides great information about choosing the right canner. This is also a great way to save money and build up food storage. Thanks for sharing!


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