Boiling-water Canners safely Preserves High Acid Foods

Canning in a boiling water bath is one of two safe methods available to home canners. Canning in a pressure canner is the other. 

The method to use is determined mostly by the acidity of the food to be canned. To be safe, low acid foods like vegetables, meats, fish and poultry must be processed in a pressure canner. Fruits, pickles, most tomato products, jams and jellies are safe when canned in a water bath, also known as a boiling-water canner.

Boiling-water canners are usually made of aluminum or porcelain-covered steel. They have removable, perforated racks and fitted lids. The canner must be deep enough so that at least one inch of briskly boiling water will cover the tops of jars during canning. Boiling-water canners with ridged bottoms can be used only on a gas range. Those with flat bottoms can be used on either a gas or electric range. On an electric range, the canner should not extend more than two inches beyond the edge of the burner.

A boiling-water canner can be improvised using a stock pot. Jars will break if they sit on the bottom of the pot, so line the bottom with jar rings or use a round cake rack. Remember, the pot must be deep enough for jars to be covered by at least an inch of boiling water.

Boiling-water canning: step-by-step

1. Fill canner halfway with water. Start heating water, but do not allow water temperature to go above 140ºF for raw-packed foods to avoid cracking jars as they go into the hot water.

2. Fill jars and close with two-piece lids, then load into canner using a jar lifter.

3. Add more boiling water if needed so water level is at least one inch above jar tops. Do not pour water directly on jar tops.

4. Turn heat to its highest setting until water begins to boil vigorously.

5. Set a timer for the minutes required for processing the food. Be sure to use the correct time for your altitude.

6. Cover the canner and lower the heat setting to maintain a gentle boil throughout the processing time.

7. Add more boiling water if needed to keep water level at least one inch above the jars.

8. At the end of the processing time, turn off the heat and remove canner lid.

9.  Use jar lifter to remove jars and place on a towel to cool. Leave at least one inch of space between jars during cooling.

10. Check seal 12-24 hours after processing by pressing the middle of the lid. If the lid is curved down slightly in the center and does not spring back when released, it is sealed. 

More detailed information about boiling-water canning and pressure canning step-by-step can be found in our guide sheet GH1452 Steps to Success in Home Canning, available for $.75 from your county extension office or on line at http://extension.missouri.edu/explore/hesguide/foodnut/gh1452.htm 
Individual guides are also available for fruits, tomatoes, jams and jellies, and pickles.

Other April 2004 Articles:
   "Hey Hon, Is the Stuff Any Good?"( A Primer on Expiration Dates)
   Food Preservation Resources: Where to go to Find Those  "In the Know
   Garden Guidelines

Cynthia Fauser
fauserc@missouri.edu
Nutrition Specialist

 

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		stcharlesco@missouri.edu Updated 04/02/07