Techniques for Home Canning

To ensure consistent results in home canning, use standard canning jars or jelly glasses with matching lids. Examine each jar or glass carefully and discard those with covers that do not fit securely and those with cracked or chipped edges. An airtight seal is essential to prevent the spoilage of food.

Wash the jars, glasses, lids and rings in hot soapy water and rinse them in scalding water. Place them in a large deep pot and pour in enough hot water to cover them completely. Bring to a boil over high heat, then turn off the heat while you finish cooking the food that you plan to can. The jars or glasses must be hot when they are filled, (If you have a dishwasher with a sanitizing cycle, simply run the jars, glasses, lids and rings through the cycle, using your usual dishwashing powder, and leave them in the closed machine until you are ready to can.)

To prepare for sealing the glasses, grate a 4-ounce bar of paraffin into the top of a double boiler preferably one with a pouring spout), and melt the paraffin over hot water.

When the food is ready for canning, lift the jars or glasses from the pot or dishwasher with tongs and stand them upright on a level surface. Leave the lids and rings in the pot (or dishwasher) until you are ready to use them" Fill and seal the jars one at a time, filling each jar to within 1/8 inch of the top or each glass to within 1/2 inch of the top. Each jar should be sealed quickly and tightly with its ring and lid. (If there is not enough food to fill the last jar or glass completely, do not attempt to seal it. Refrigerate and use within the next week.)

The jelly glasses also should be sealed at once. Pour a single thin layer of hot paraffin over the surface of the jelly, making sure it covers the jelly completely and touches all sides of the glass. If air bubbles appear on the paraffin, prick them immediately with the tip of a knife. Let the glasses rest until the paraffin cools and hardens, then cover with metal lids.

If a recipe calls for finishing the preserving process with a water bath, place the filled and sealed jars side by side on a rack in a canner or other deep large pot. Pour in enough hot (not boiling) water to cover the jars by at least 1 inch, securely cover the pot with its lid, and bring to a boil with moderate heat. Boil for the time recommended in the particular recipe. Then, with tongs, remove the jars from the pot and let them cool at room temperature for about 12 hours. Test the seal by pressing the center of each lid with your forefinger. If the inner lid remains in place, unscrew the outer ring, leaving the seal intact. Store the jar upright in a cool, dry dark spot. If the lid moves at all, the jar is not properly sealed; in that event, refrigerate and serve the food within the week.

For additional information on canning, see "How to Make Jellies, Jams and Preserves at Home," USDA Home and Garden Bulletin No.56, and "Making Pickles and Relishes at Home," USDA Home and Garden, Bulletin No. 92. These bulletins cost 15 cents each and can be ordered from the Superintendent of Documents, U.S. Government Printing Office, Washington. D.C. 20402.