Reliable Research-Based Methods for Home Canned Tomatoes

— Written By

image

Tomatoes are plentiful this season and recent callers are seeking advice regarding safe home canning methods for tomato products. Just as the varieties of tomatoes in the markets keep changing and increasing in number, it is important to remember we have a variety of directions for canning tomatoes.

Only boiling water or pressure canning methods are recommended for canning tomato products. Older methods, such as oven canning and open-kettle canning, have been discredited and can be hazardous.

Reliable, tested recipes for canning a variety of tomato products will often give the option of canning either in a pressure canner or a boiling water bath. The boiling water and pressure alternatives are equal processes with different time and temperature combinations calculated for specific products. Some recipes will provide only boiling water bath times and others will give only pressure canning times. The recipes that specify only pressure canning have so many low acid ingredients added to them that they are only safe when canned in a pressure canner at the specified pressure. The process times are very different for tomatoes packed in water compared to tomato juice or without added liquid.

No matter how you choose to can your tomatoes, follow all preparation steps and processing guidelines carefully.

Acidification

Tomatoes for many years were considered high acid. However, new varieties, over-mature fruits, and tomatoes from dead or frost-killed vines may have a low acid content. Because tomatoes have borderline pH values (measure of acidity) between acid and low acid foods, you must take some precautions to can them safely. Whether your tomatoes will be processed in a boiling water bath or a pressure canner, add acid. To acidify whole, crushed or juiced tomatoes, add two tablespoons of bottled lemon juice or one-half teaspoon citric acid per quart of tomatoes. For pints, use one tablespoon of bottled lemon juice or one-fourth teaspoon citric acid. Acid can be added directly to the jars before filling with product; in fact, this is recommended to be sure you get the acid in each and every jar. Sugar may be added to offset an acid taste, if desired, but the acid cannot be decreased to taste. Four tablespoons (5 percent acidity) vinegar per quart may be used instead of lemon juice or citric acid. However, vinegar may cause undesirable flavor changes.

Here is a summary of the only safe alternatives for canning tomatoes according to the United States Department of Agriculture (USDA) guidelines:

  • Crushed Tomatoes, a hot-pack-only version of cooked quartered tomatoes
  • Whole or Halved Tomatoes, with boiling water or tomato juice to cover, with raw or hot pack versions available
  • Whole or Halved Tomatoes, with no added liquid, raw pack only; tomatoes are pushed tightly into the jars to create juice as the jar fills
  • Tomato Juice and Tomato-Vegetable Juice Blend, as hot packs only
  • Tomato Sauce, hot pack only

Canning your tomatoes does not have to be too complicated, if you use reliable, research-based printed directions for preparing and processing your food.

Adapted from the National Center for Home Food Preservation

North Carolina Cooperative Extension, Cleveland County Center, for more information on food and nutrition and food safety, contact Nancy Abasiekong by phone: 704-482-4365, by e-mail: nancy_abasiekong@ncsu.edu, or by mail: 130 South Post Road, Suite 1, Shelby, NC 28152