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Safely preserve your garden tomatoes

Media contact:

Rebecca Gants
Senior Information Specialist, West Central Region
University of Missouri Cooperative Media Group
Phone: 816-812-2534
E-Mail: gantsr@missouri.edu

Published: Monday, July 6, 2009

Story sources:

Glenda Kinder, 816-407-3490
Tammy Roberts, 417-682-3579

BLUE SPRINGS, Mo. – If your garden is producing more tomatoes than you know what to do with, canning or freezing lets you enjoy your tomatoes throughout the year. However, make sure you follow proper procedures to keep your produce safe and flavorful, said a University of Missouri Extension nutrition and health education specialist.

“Folks may be afraid to do home canning for fear they’ll cause a family member or friend to get sick,” said Glenda Kinder. “Today’s canning recommendations are research-based, so if you follow those procedures, you can be confident in the safety of the finished product.”

Unlike most vegetables, tomatoes can be safely water-bath canned because of their higher acidity, but you will need additional acid to keep microorganisms at bay.

This is true even of heirloom tomatoes. “Gardeners have been asking if these tomatoes are acidic enough to be canned without added acid,” Kinder said. “University horticulture researchers have concluded the pH of heirloom plants is no different from the non-heirloom varieties, so the same recommendations apply for acidifying.”

Use only firm, ripe tomatoes for canning. Tomatoes that are overripe, soft, moldy or picked from dead vines may not be acidic enough.

Kinder recommends two tablespoons of bottled lemon juice or a half-teaspoon of citric acid per quart. Halve the amount of lemon juice or citric acid for pint jars. You can add a pinch of sugar to offset the acid taste.

Use only jars specifically designed for canning. Check rims for chips or cracks. Wash the tomatoes and place in boiling water until the skins split, about 30-60 seconds. Dip in cold water, peel skins then cut in half or leave whole.

Add bottled lemon juice or citric acid to canning jars, leaving a half-inch of space at the top. Process jars in boiling water for 50 minutes. After cooling jars at room temperature for 12 to 24 hours, test the seals. Lids should be concave (curved inward) and not move up or down when you tap on them.

If you would rather not tackle canning, or have tomatoes that are overripe but otherwise sound, you can freeze them instead.

Freezing tomatoes is easy, said MU Extension nutrition and health education specialist Tammy Roberts. Just wash and dip in boiling water then slip off the skins and remove blemishes. You can seal them, whole or in pieces, inside freezer bags.

“It is best to use frozen tomatoes for cooking because they will not be solid when thawed,” Roberts said. “I put frozen tomatoes in crock pot soups, stews and chili.”

Publications featuring research-based recipes for preserving a variety of foods are available from MU Extension at http://extension.missouri.edu/main/DisplayCategory.aspx?C=194.