Roma tomatoes are also known as Italian or plum tomatoes. With their prolific yields of meaty, sweet fruit, they make the ideal tomato for sauces, canning and freezing. And unlike many vegetables, tomatoes are actually more nutritious cooked than raw. If you’ve never preserved tomatoes before, you’ll find the process quick and surprisingly simple. Read on to learn everything you need to know to can or freeze Roma tomatoes.
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Canning Roma Tomatoes
Because Roma tomatoes are slightly acidic, they may be safely processed in a water bath canner, rather than a pressure canner. You’ll need about 3 pounds of tomatoes per quart jar or 1 ½ pounds for each pint. Don’t forget to peel the tomatoes. Any bits of peel remaining on the fruit become tough and stringy in the jar. Here are the step-by-step directions for canning tomatoes:
- Wash fresh, ripe tomatoes. Avoid those with cracks, spots or soft spots.
- Place the tomatoes in a pot of boiling water for 30 to 60 seconds, or until the peels start to crack. If you have a metal colander basket, place the tomatoes in the basket and drop them in the pot so you can easily drain them.
- Use a paring knife to slip off the loosened skins. Cut out the green stems and the cores. Leave tomatoes whole, quarter or dice them.
- Warm jars in a pot of hot (but not boiling) water until they are ready to be filled (this will prevent them from breaking when they are immersed in boiling water later).
- Place the prepared tomatoes in the hot quart or pint jars. Add 2 tablespoons bottled lemon juice or ½ teaspoon citric acid to quart jars. For pint jars, use 1 tablespoon bottled lemon juice or ¼ teaspoon citric acid. The lemon juice or citric acid serve two purposes. First, they keep the fruit fresh and preserve its bright color. More importantly, though, they slightly acidify the tomatoes, ensuring a safe canning product. Citric acid is a fine white powder available in bulk at natural food stores, where it is very inexpensive. You can also find packaged citric acid in the canning supply section of most grocery stores. In general, citric acid is more convenient and less expensive than bottled lemon juice.
- Press down on the tomatoes so that the juice fills the jars, leaving ½ inch headspace. Add 1 teaspoon salt to each quart jar or ½ teaspoon salt to each pint. If you prefer, you can omit the salt.
- Remove any air bubbles by stirring with a plastic spoon or spatula. Wipe the rims with a damp cloth and place the seals and rings on the jars, tightening the rings securely.
- Set the jars in a water bath canner filled with water. Place the lid on the canner and bring the water to a boil. Continue boiling pint jars for 40 minutes, quart jars for 45 minutes.
- Remove the jars from the canner with a jar lifter and place them on a towel on the counter top. Don’t touch the jars or rings. Allow them to cool overnight. Press on the lids to make sure the jars have sealed. Wipe the jars clean and store them in a cool, dark place.
Freezing Roma Tomatoes
Freezing Roma tomatoes is even simpler than canning them because you don’t have to remove the skins. Instead, you’ll puree the tomatoes for use in soups, marinara sauce or fresh-tasting salsas. Here’s how:
- Choose firm, ripe Roma tomatoes without blemishes or cracks.
- Cut out the green tops and the cores. Quarter the tomatoes or leave them whole.
- Cook the tomatoes in a pot of simmering water until soft, approximately 15 minutes.
- Drain the tomatoes and process them through a food mill or food processor until pureed. You can leave them slightly chunky or puree them until completely smooth. Add salt to taste if you like, or leave the tomatoes unsalted.
- Ladle the tomato puree into quart or gallon zip-top freezer bags.
- Remove as much air as possible from the bags and lay them flat in the freezer. Once frozen, you’ll have a thin, flat product that takes up much less room than freezer boxes. Stack the bags one on top of each other for convenience.
- To use frozen tomatoes, thaw them in the refrigerator overnight or set them on the countertop for an hour.
Want to know more? Here are a few resources on preserving Roma tomatoes:
Canning and Freezing Tomatoes from the Iowa State University Extension.
Complete Guide to Canning from the National Center for Food Preservation.
By Julie Christensen
When she’s not writing about gardening, food and canning, Julie Christensen enjoys spending time in her gardens, which includes perennials, vegetables and fruit trees. She’s written hundreds of gardening articles for the Gardening Channel, Garden Guides and San Francisco Gate, as well as several e-books.