Canning tomatoes: Essential safety tips

Learn how easy it is to preserve locally-grown tomatoes following the most up-to-date methods.

Tomatoes are one of the most popular foods to preserve. Preserving in the summer allows you to capture the quality of freshly picked tomatoes at their peak. Home-canned tomatoes are versatile and allow you to create a variety of recipes throughout the year. Despite their popularity and versatility, tomatoes are often canned incorrectly by home food preservers. Taking a few minutes to quickly review your recipe, process and time, will ensure that your home-canned foods will be safe and tasty.

It is essential to use research-based information as your resource for home food preservation. The U.S. Department of Agriculture or the National Center for Home Food Preservation are perfect sites to get the most up-to-date directions for preserving tomatoes. One of your first decisions is to decide how you plan to use the tomatoes. If you want flexibility, you may want to preserve them using the crushed tomato recipe. That is ideal for soups, stews and casseroles. But if you would like to just pull a jar of sauce off the shelf and have it ready to go, canning tomato sauce may be your best option. Be sure to consult the National Center for Home Food Preservation for exact recipes and processing times.

An essential safety step for preserving any tomato products regardless of processing method is the addition of citric acid or lemon juice to each individual jar of tomatoes. Tomatoes are not acidic enough naturally to safely preserve. Add bottled lemon juice or food-grade citric acid to the jars before processing:

  • If using bottled lemon juice, use 1 tablespoon per pint or 2 tablespoons per quart.
  • If using citric acid, use 1⁄4 teaspoon per pint or 1⁄2 teaspoon per quart.

It may be tempting to make your own unique tomato recipe, but it isn't a safe practice for home food preservation. The additional ingredients may adjust the pH of the food and may no longer be safe to preserve. The most common tomato based food that is prone to recipe deviation is salsa. Everyone has their own personal salsa recipe that they have perfected. But for home food preservation, be sure to only use approved recipes from research-based resources.

Preserving tomatoes at the peak of freshness provides a winter full of delicious, quality tomatoes to use in all your favorite recipes. You can also control the additives and preservatives in your food by canning your own foods.

For more information on canning safely, see “Common food preservation mistakes: An eight question quiz on canning safely.”

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