Gardening Articles: Care :: Tools & Equipment
Preserving Tomatoes: Canning
by National Gardening Association Editors
Boiling Water Bath Canning
Because instructions accompanying canners sometimes vary, follow the instructions that came with yours.
Assemble All Utensils
Use only mason jars for home canning; they're made by several manufacturers. These jars are safe for canning because the glass is heat-tempered, and they seal perfectly.
Never reuse dome lids for canning. After one use the rubber compound loses its ability to seal correctly. Metal screw bands and mason jars may be reused.
Examine and Clean All Equipment
Wash all equipment thoroughly, and scald in hot water. Keep jars and screw tops hot until ready to use. Follow manufacturer's directions for preparing the metal lids.
Use the Freshest, Cleanest Tomatoes
Wash tomatoes well. Peel by dunking them in briskly boiling water for 30 seconds, then in cold water. Handle tomatoes gently as you slip off the skins. Remove the stems and any green spots from the peeled tomatoes; don't use any that are overripe or unhealthy. One bad tomato is like one bad apple - it can spoil the whole batch.
Tomatoes don't always have to be peeled. If they're going to be used in smooth sauce or in juice, the skins will be eliminated when they're sieved or strained.
Raw Pack: In advance prepare enough tomato juice to be the canning liquid for the batch - you'll need 1/2 to 3/4 cup juice for each pint, one to 1-1/2 cups for each quart. Do not dilute the acidity of the juice by thinning it with hot water; if you run out of homemade juice, use canned tomato juice.
Peel unblemished tomatoes and fit them whole into clean, scalded jars snugly, but without pressing so much that you break them. Leave 1/2 inch of headspace for pints, one inch of headspace for quarts. Add 1/4 teaspoon crystalline citric acid (or one tablespoon lemon juice) to pints, 1/2 teaspoon citric acid (or 2 tablespoons lemon juice) to quarts. Then add boiling tomato juice, leaving 1/2 inch of headspace for both pints and quarts (release any air bubbles by running the blade of a table knife around the edge of the jar). Wipe jar top and threads with a clean, damp cloth. Put lid, rubber side down, on jar and screw band on firmly.