Canning Tomato Sauce (Safe, Step-by-Step)

What Makes This Recipe Work

Tomatoes are borderline in acidity, so the added bottled lemon juice or citric acid guarantees each jar sits below pH 4.6, which is what allows a boiling-water bath instead of a pressure canner.

Ingredients for Canning Tomato Sauce (Safe, Step

• 12 lb (5.4 kg) ripe plum or Roma tomatoes, cored and quartered (about 36 to 40 tomatoes)
• 2 tbsp olive oil
• 1 medium onion, chopped (keep the amount small so the sauce stays in the tested acid range)
• 2 garlic cloves, minced
• 1 tsp dried oregano
• 1/2 tsp ground black pepper
• 2 dried bay leaves
• 1/4 cup chopped fresh basil
• 1 tsp salt per pint, optional
• 1 tbsp bottled lemon juice per pint jar, or 1/4 tsp citric acid per pint (do not omit)

How to Make Canning Tomato Sauce (Safe, Step

1. Wash and core the tomatoes, then cut them into quarters and simmer them in a large nonreactive pot, uncovered, for 20 to 25 minutes, stirring occasionally, until they soften and release their juice.
2. Heat the olive oil in a small skillet over medium heat and cook the onion until soft, about 5 minutes, then add the garlic and cook 1 minute more.
3. Run the softened tomatoes through a food mill or press them through a fine sieve to remove skins and seeds, discarding the solids.
4. Return the strained tomato puree to the pot with the cooked onion and garlic, oregano, black pepper, and bay leaves, and simmer uncovered 40 to 50 minutes, stirring often, until the sauce is thick enough to mound on a spoon.
5. Add the basil in the last 5 minutes and discard the bay leaves; keep the sauce hot while you prepare the jars and a boiling-water canner.
6. Add 1 tbsp bottled lemon juice (or 1/4 tsp citric acid) and 1 tsp salt, if using, directly into each hot pint jar before filling.
7. Ladle the hot sauce into the jars over the acid, leaving 1/2 inch of headspace, run a bubble tool around the inside, wipe the rims, and cap with lids and fingertip-tight bands.
8. Process pints in a boiling-water bath for 35 minutes and quarts for 40 minutes at 0 to 1,000 ft elevation, adding 5 minutes for every 1,000 ft above that; cool undisturbed 12 to 24 hours, check the seals, and refrigerate any jar that did not seal.

Tips for the Best Canning Tomato Sauce (Safe, Step

• Use only commercially bottled lemon juice, because its acidity is standardized, while fresh lemon juice varies from bottle to bottle.
• Never thicken tomato sauce for canning with flour or cornstarch; reduce it by simmering instead.
• Keep added low-acid vegetables such as onion and pepper to a small amount, since large quantities change the pH.
• A food mill gives a smooth sauce and leaves the skins and seeds behind without peeling each tomato by hand.

Variations and Substitutions

• Simmer in 1 tsp dried basil and a pinch of red pepper flakes for a spicier Italian-style sauce.
• Leave the sauce thicker for pizza and bruschetta, or looser for pasta by shortening the simmer.
• Use a tested canning salsa recipe if you want a chunky tomato and pepper dip instead of a smooth sauce.
• For a fresh, uncooked tomato dip, make homemade salsa or salsa verde and refrigerate rather than can.

How to Store and Reheat

• Store sealed jars in a cool, dark place for up to 18 months, and refrigerate after opening.
• Refrigerate any unsealed jar and use it within 3 to 4 days.

Canning Tomato Sauce (Safe, Step FAQ