How to Can Diced Tomatoes
Having canned goods in your pantry that you made yourself is a great feeling, especially in the middle of winter when you need some freshness. This diced tomatoes canning recipe tastes fresher than store-bought and uses only 3 ingredients (okay plus water)! Waterbath canning is a great way to save food from a big summer harvest, and this is the perfect recipe to get you started.
Diced Tomatoes for Canning
Equipment
- 6 pint jars + rings and lids
- Large pot
- large bowl
Ingredients
- 7 pounds Roma tomatoes about 33 tomatoes
- 6 tablespoons bottled lemon juice
- 3 teaspoons canning salt
- 4 cups water + more for cleaning, removing skins, and processing
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Instructions
- Prep jars. Wash mason jars with hot, soapy water and place in waterbath canner. Fill with water until jars are fully submerged. Cover with lid, place over medium heat, and simmer. Wash rings and lids in hot, soapy water and set aside.
- Score. Boil a large pot of water. While the water is boiling, gently score the bottom of the tomatoes with an X.
- Prep ice-bath. Fill a large mixing bowl with ice about halfway, then fill with water until it is ¾ way full.
- Boil, ice, and remove skins. Once water is boiled, place 5-6 tomatoes in at a time, working in batches. Boil for 30-90 seconds or until the skin starts to pull away from the tomato. Move to the prepared ice water bath. Peel the skins off the tomatoes. Repeat this process. (Don’t skip removing the skins. This is important for texture and heat distribution)
- Dice. Remove the core, slice the tomatoes in half, then dice them. You will want about 16 cups of diced tomatoes.
- Boil. Place diced tomatoes in a large stainless steel pot. Add 4 cups of water. Boil over medium heat for 5 minutes, stirring constantly so they don’t stick to the bottom or boil over. Remove from the heat.
- Fill jars. Remove the jars from the waterbath canner. Add 1 tablespoon of lemon juice and ½ teaspoon of canning salt in each jar. Ladle the hot diced tomatoes into the jars, leaving ½ inch of headspace in each jar.
- Debubble, wipe, and fasten. Use a debubbler to remove any air bubbles. Add more tomatoes to maintain a ½ inch headspace. Wipe the rims with a clean, damp towel. Place the clean lids and rings on the jars. Tighten the rings so they are fingertip-tight.
- Process. Place filled jars in the waterbath canner. Fully submerge them in water with at least 1 inch of water above the jars. Add a splash of white vinegar (optional to prevent build-up from forming on the outside of the jars). Bring the water to a boil. Once boiling, set a timer for 40 minutes for pint jars (45 minutes for quart jars), adjusting for altitude.
- Cool. After 40 minutes, remove the canner from the heat and remove the lid. Let the jars sit for 5 minutes. Remove the jars from the canner and place in a heat-safe area. Cool for 12-24 hours.
- Check seals and store. Once completely cooled, check the jars for a proper seal. If a proper seal has been confirmed, label the jars and store them in a cool, dark place for up to 18 months or per your lids manufacturer’s recommendations. If a proper seal has not been made, refrigerate immediately and use within 3 days.
Notes
- Roma tomatoes are best because they give you the most sauce.
- To can using quart jars, increase the amount of lemon juice to 2 tablespoons of bottled lemon juice and increase the amount of salt to 1 teaspoon, per jar. Increase your processing time to 45 minutes.
- Nutrition facts are for 1 pint-sized jar.
Nutrition
Roma tomatoes are perfect for this recipe because their meaty texture holds up during processing and they have less water content than other varieties. The process looks time-consuming, but most of it is waiting while the canner does its job.
The bottled lemon juice is essential for safety, not just flavor. Tomatoes are borderline between high and low-acid foods, and that extra acidity ensures they’re safely preserved without pressure canning.
Tips for Success
Watch your boil time when removing skins – about 30-90 seconds is perfect. When you see the skin just starting to pull away, that’s your cue.
Try to dice uniformly for even heating during processing. They don’t need to be perfect, but similar-sized pieces process more consistently.
Run your debubbler or plastic knife around the inside of each jar thoroughly. Those hidden air pockets can lead to spoilage.
“Fingertip-tight” means just that – tighten rings until you feel resistance, then stop. Overtightening prevents air from escaping during processing.
Let jars cool undisturbed for the full 24 hours. Moving them too soon can interfere with the sealing process.
Always adjust the processing time if you live at a higher altitude. You can check this chart for altitudes and processing times.
Ingredients and Equipment
Roma tomatoes: Their dense flesh and lower moisture make them ideal. Other varieties work too, but you’ll likely need to drain more liquid.
Bottled lemon juice: Non-negotiable for safety. The acidity level is standardized, unlike fresh lemons.
Canning salt: Regular table salt contains anti-caking agents that can make your tomato liquid cloudy.
Water bath canner: Essential for proper processing. Beginners can use a large stock pot with a rack in the bottom, but a proper canner makes the job easier.
Debubbler: Helps remove air bubbles and check headspace. A plastic knife works in a pinch.
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Make It Your Own
Canning recipes can’t be changed drastically for safety reasons, but here are a few small ways to adjust the recipe.
- Use different tomatoes. Any tomato variety will work, though juicier types will produce more liquid. Either drain some juice before jarring or embrace the extra liquid.
- For Italian-inspired tomatoes, add a teaspoon of dried basil and oregano to each jar. For French flavor, add a garlic clove and a sprig of thyme.
- Dice larger for more texture or smaller for ready-to-use sauce consistency. Or crush them to make home canned crushed tomatoes.
Home-canned tomatoes can help you save money and be more connected to the food you’re eating. The process is straightforward, and once you’ve done it once, you can enjoy it all year.
By Katie Shaw
Katie shares simple, reliable recipes from her home in Virginia, where she lives with her husband, three daughters, a chocolate lab, and over thirty chickens.