For safety, it's always important to use careful canning techniques. Because tomatoes - with the exception of the low-acid types - contain sufficient acid, they may be canned safely in a boiling water bath rather than in a pressure canner as required for all other vegetables. If you're canning tomato sauce containing meat or other vegetables, however, you must use the pressure-canning method.
Because instructions accompanying canners sometimes vary, follow the instructions that came with yours.
Assemble All Utensils
Canner with rack, mason jars, lids, tongs or jar lifter, timer, cooling racks, wide-mouth funnel, slotted spoon, nonmetallic spatula.
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
Check all bands for rust, dents or nicks and the jars for chips or cracks. Recycle them or use them in the workshop or elsewhere if they aren't perfect.
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
One bushel of tomatoes will yield about 18 quarts of tomatoes; three pounds of tomatoes will produce one quart. If you cook them down for sauce, paste or juice, the yield varies.
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.
In a large pot, bring chopped tomatoes to a boil in their own juice. Boil for five minutes, stirring constantly. Pour the hot tomatoes into hot jars, leaving 1/4 inch headspace for pints, 1/2 inch 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. Wipe jar tops and threads with a clean, damp cloth. Put lid, rubber side down, on jar and screw band on firmly.
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.
|1. Ripening and Harvesting Tomatoes|
|2. Preserving Tomatoes: Freezing|
|3. Preserving Tomatoes: Canning ← you're on this article right now|
|4. Drying Tomatoes|