Preserving Your Tomato Harvest

The tomato is a much-loved and incredibly versatile fruit. Tomatoes are simply delicious eaten warm off the vine, chopped or sliced for salad, gazpacho, or salsa. A bit more effort yields the freshest pasta sauce, savory tarts, and soups—redolent with its summery flavor.

To make this delectable fruit last long after the growing season is over, it can be preserved—dried, canned, and frozen—into myriad forms and flavors. Preserving saves money, reduces waste, ensures the quality of your food, and creates interesting, tasty, and useful foodstuffs to serve your family and to give as gifts. It is also extremely satisfying and fun!

Begin with the highest quality, perfectly ripe, disease-free fruit. Ideally, pick your tomatoes in the morning after the dew has dried, but before the heat of the day has softened and warmed the fruit. Preserve as close to harvest as possible to ensure the highest quality flavor and nutritional content.

Second, preserve what you like to eat. Each year, I create tomato-based pizza sauce, salsas, interesting pasta sauces, spiced tomato jam, and jars of whole tomatoes and tomato sauce. Explore new recipes every year to add to your repertoire. This season, I plan to experiment with oven-drying sliced or halved Roma tomatoes, then roasting them with a variety of herbs, vinegars, and a little fruity olive oil. Once cooled, they are placed in freezer-quality plastic bags, layered between parchment paper, and frozen. I envision pulling them out on a dreary winter day, adding the essence of summer to soups, sauces, salads, and pizza.

Third, follow research-based recipes and processes to ensure safety and quality. Two excellent sources to get you started include Penn State's publication Let's Preserve: Tomatoes and publications from the National Center for Home Food Preservation.

Dried fruits can be safely held at room temperature. Tomatoes cannot be sun-dried in Pennsylvania; our weather is too humid and not consistently hot enough. Instead, use a dehydrator or oven (set at 140 to 150°F with the door ajar 2 to 6 inches). Prepare larger tomatoes by steaming or dipping them in boiling water for thirty seconds to crack and loosen the skin. Cool immediately in ice water, peel, and core. Slice half-inch thick or cut into three-quarter-inch sections. There is no need to peel cherry or small Roma tomatoes—just cut them in half. Drying time is six to twenty-four hours. They will be leathery to crisp when dry. Once cool, store in labeled airtight containers in a cool, dry, dark location and use within one year.

Freezing is easy and, if done properly, the method that retains the most vitamins. Freeze items quickly and maintain a temperature of 0°F or colder. Once peeled and cored, tomatoes can be frozen raw either whole, chopped, or as juice. Cooked-down or stewed tomatoes can also be frozen. Use freezer-safe, airtight, labeled containers. Allow one inch of space between the top of the tomatoes and the lip of the container. This "headspace" allows for the expansion that occurs when moisture-rich items freeze. Thaw only in the refrigerator or in the microwave at the start of the cooking process

Another shelf-stable option is canning. Canning tomatoes results in vacuum-sealed jars that are stored in cool, dry, dark places. There is also an initial investment in equipment for processing and storing the harvest. A canning pot is needed for hot water bath processing of high-acid recipes. Low-acid recipes require a pressure canner.

For food safety reasons, it is extremely important to follow both research-based processes and recipes. Tomatoes are on the cusp of what food scientists would consider to be “acidic" foods, and failing to adequately increase the acidity can result in deadly botulism poisoning. To ensure safe acidity in whole, crushed, or juiced tomatoes, add 2 tablespoons of bottled lemon juice per quart of tomatoes, or 1 tablespoon per pint. Only use bottled lemon juice because the acidity level is constant.

Salsas are generally a combination of tomatoes and other low-acid vegetables—peppers, onions, and herbs. There are tested recipes that use lemon juice, vinegar, or bottled lime juice to acidify salsa, which can then be safely canned. Without an acidifying agent, it is best to freeze salsa.

When your garden overflows with tomatoes, spend a little time preserving your bounty, and you can pass on the flavorless tomatoes found on grocery shelves once the growing season has passed.