Burning Issue: Canning Homemade Soups
Can I can my favorite soup recipe at home?
Canning soup at home is an excellent way to preserve your vegetables with or without small portions of meats or seafood. The key to canning a safe, high quality soup is to follow directions provided by a reliable science-based source like USDA or partners in the Cooperative Extension System.
Vegetable-based soups are usually mixtures of low-acid ingredients and they need to be pressure canned by a process that has been developed by research methods known to control for botulism food poisoning; we will not recommend any way to can vegetable or vegetable-meat soups in a boiling water canner. Botulism is a potentially fatal foodborne disease. Spores of the organism (Clostridium botulinum) that causes botulism can survive normal cooking temperatures and times. The extra heat in pressure canning is needed to actually destroy the spores so when the closed jar sits at room temperature in storage, the spores will not grow out to cells that then produce the deadly botulinal toxin. The conditions in the sealed jar at room temperature are favorable for this organism to cause problems (moist, low in acid with a pH above 4.6 and very low in oxygen).
There is only one version of pressure canning directions for home canned soups available from USDA and on this website. Consumers should follow these directions exactly: http://www.uga.edu/nchfp/how/can_04/soups.html. If additional ingredients or thickening is desired, the soup should be canned as described and those variations should be made when the jar is opened for serving.
The USDA procedure is not an exact recipe; it allows you to have some choice of vegetables, dried beans or peas, meat, poultry, or seafood. It does NOT allow you to include noodles or other pasta, rice, flour, cream, milk or other thickening or dairy ingredients.
If dried beans or peas are used, they must first be fully rehydrated (for each cup of dried beans or peas add 3 cups of water, boil 2 minutes, remove from heat, soak 1 hour, heat to boiling, drain).
Each vegetable should be selected, washed, prepared and cooked as you would for canning a ‘hot pack’ according to USDA directions. (On our website, look under “How Do I….Can….Vegetables” or “How Do I….Can…Tomatoes”: http://www.uga.edu/nchfp/how/can_home.html.) If there is not a separate canning recommendation for a vegetable, do not include it.
Meats recommended for canning should be covered with water and cooked until tender, then cooled and the bones removed. Next, all the prepared ingredients should be cooked together with hot water, broth or tomatoes, to boiling, and boiled for 5 minutes. Salt can be added to taste, if desired. Do not fully cook the soup before filling jars; the canning process completes the cooking at the same time it eliminates harmful microorganisms.
A very important step in these procedures is that jars should only be filled halfway with the mixture of solids. The rest of the jar is filled with the hot liquid leaving 1-inch headspace.
Process the jars in a pressure canner according to instructions in the table relevant to your altitude, pressure canner type and jar size.
February 19, 2015
National Center for Home Food Preservation