HE-136
CANNING TOMATOES
General Procedures
Selection
Use only fresh, firm tomatoes. Do not can overripe tomatoes. (These can be eaten fresh.) The acid content of tomatoes decreases as tomatoes ripen on the vine or under certain storage conditions. If you must store tomatoes before canning, keep them in a cool, airy place. If you buy tomatoes, try to get them from a nearby source.
Acid vs Low-Acid Varieties
The acid content of hundreds of varieties of tomatoes used for home canning has been tested. All tested varieties contained enough acid to be safely canned in a boiling-water-bath if recommended procedures are used. However, 1/4 teaspoon of citric acid or 1 teaspoon of lemon juice may be added for each pint of tomato.
Whole Tomatoes
For easy peeling, dip tomatoes into boiling water for approximately 1/2 minute; then dip quickly into cold water. Cut out stem ends and peel tomatoes. The peeled tomatoes may then be raw or hot packed.
Raw pack. Leave tomatoes whole or cut into halves or quarters. Pack tomatoes into clean, glass jars to within 1/2 inch of top, pressing gently to fill spaces. Do not add water. If desired, for flavor, add 1/2 teaspoon salt to pints; 1 teaspoon to quarts. Wipe jar rim clean.
Hot pack. Quarter peeled tomatoes and place in clean saucepan. Bring to boil, stirring to keep tomatoes from sticking.
Pack boiling hot tomatoes in clean, glass jars to within 1/2 inch of top.
Add salt if desired. Wipe jar rim clean. Follow manufacturer's directions to apply the closure in the raw or hot pack method.
Tomato Juice
Use ripe, juicy tomatoes, wash, remove stem ends, and cut into pieces. Simmer until softened, stirring often.
Put through a strainer. Add 1 teaspoon salt to each quart of juice. Reheat the juice, to boiling point.
Fill clean, hot, glass canning jars with boiling-hot juice to within 1/2 inch of top. Adjust lids. Process in boiling-water-bath (212°F.). (See Processing).
Processing Boiling Water Bath
Tomatoes can be safely processed in a boiling-water-bath.
Put filled glass jars into canner containing water. For raw pack, have water hot but not boiling; for hot pack, use boiling water.
Add boiling water to bring water level one or two inches over the tops of the containers (see illustration).
Don't pour boiling water directly on glass jars. Put cover on canner. Boil gently and steadily for the recommended time.
To keep jars covered during processing, add boiling water as necessary.

Cooperative Extension Service, Purdue University, West Lafayette, Indiana