Tomatoes (2010)

People produce more home-canned tomatoes than any other home-canned product. However, you must can tomatoes carefully to avoid the risk of spoilage and food poisoning. The natural acidity in tomatoes varies widely because of differences in ripeness, growing conditions, injury or disease on the fruit, and vine conditions. Some tomato varieties, like the paste or Roma types of tomatoes, are lower in acid than most other varieties, but even high-acid varieties can produce lower-acid fruits under some conditions. Because of these factors, you should add acid in the form of lemon juice or citric acid to all home-canned tomato products. Add two tablespoons of bottled lemon juice per quart of tomatoes, tomato juice, or other tomato product. Add one tablespoon per pint. This ensures that the tomatoes are sufficiently acid to avoid the risk of botulism.

You may control spoilage by heat-processing filled jars of tomatoes in a boiling water canner or pressure canner. Processing times have just been carefully recalculated by researchers at the Pennsylvania State University and differ somewhat from those recommended before 1987.

Use only disease-free, preferably vine-ripened firm tomatoes for canning. Do not can overripe, damaged, or frosted tomatoes, or those harvested from dead vines. Such tomatoes are much lower in acid.

There are several different packing methods for tomatoes; however, each requires a different process time. The different options include heating the tomatoes before filling jars versus packing them with raw tomatoes. The other variables that greatly affect processing time are the size of the tomato pieces (whole, quartered, crushed, etc.) and the liquid (if any) that is used in the jar.

Hot pack method with boiling water canner#This is the easiest and quickest method. Peel the tomatoes, remove cores ,and quarter or crush them. Heat them rapidly in a large kettle and simmer gently for 5 minutes. Add two tablespoons bottled lemon juice to each quart jar, then fill with the hot tomatoes. Add one teaspoon salt if desired. Add enough cooking water to cover tomatoes, leaving a ½-inch headspace. Seal with new two-piece canning lids and process quarts 45 minutes in a boiling water canner.

Pressure canner with a dial gauge#Process whole or halved tomatoes packed in water at 11 pounds pressure for 10 minutes.

A raw whole or halved tomato packed in its own juice or in added tomato juice needs a much longer processing time to prevent spoilage and will have a less desirable appearance and texture. To each quart jar, add two tablespoons bottled lemon juice and one teaspoon salt, then fill with peeled raw tomatoes. Press them to make enough juice to cover, or add previously strained hot tomato juice. Adjust lids and process for 85 minutes in a boiling water bath canner.

In a dial gauge pressure canner, process raw juice-packed tomatoes 25 minutes at 11 pounds pressure.

Call your local Cooperative Extension office to receive a detailed copy of canning recommendations.

For more information on this subject, Please visit the College of Agricultural Sciences Publications Web site.

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