Canned Tomatoes

READY IN: 1hr 15mins
YIELD: 6 pints




  • Notes:
  • Do not refrigerate tomatoes, as refrigeration undermines the flavor.
  • Though tomatoes are a fruit, they are usually pH 4.5 to 4.6, which is right on the borderline of foods you can safely process in a water bath, so you have to acidify them by adding lemon juice or citric acid if you are planning to process them in a water bath. You can do this by adding 1/4 teaspoon citric acid or 2 tablespoons lemon juice per pint. Citric acid is sold in the US under the name "Fruit Fresh", and can be bought at most grocery stores. If you choose to use lemon juice to acidify your tomatoes, use bottled lemon juice, because bottled commercial lemon juice has a consistent pH, and fresh lemons can vary in acidity.
  • Sometimes you remove tomatoes from the boiling water bath canner to find that the pulp has separated from the juice. This is caused by an enzyme in the tomato that becomes activated when the tomato is exposed to air, either by skinning and/or cutting and crushing. The enzyme breaks down pectin, causing the solids and liquids to separate. The sooner the skinned, crushed or cut tomatoes are heated, the better, as heat stops the enzymatic action (this is also why you almost always blanch foods before freezing them). Regardless of separation, these tomatoes are still perfectly safe to eat.
  • Bring a large pot of water to a boil over high heat. Drop the tomatoes into the boiling water, count off 10 seconds, and then remove.
  • With a sharp paring knife, slit the tomato skins and peel them off. They will come off easily. Core the tomatoes and tear them in half, squeezing out the seeds. Toss into a pot. Drop the skins and seeds into a colander over a bowl. A lot of tomato juice is saved this way, which you can add to your canned tomatoes or drink fresh.
  • Crush the tomatoes. You can use a food processor or a tomato masher. Chunks are OK.
  • Heat the tomatoes and boil gently for 5 minutes. The tomatoes may get a bit foamy on top - that's OK.
  • Have ready 6 pint-sized canning jars. Into each jar, place 1/4 teaspoon dried basil, 1 teaspoon of salt, 1/4 teaspoon of citric acid OR 2 tablespoons lemon juice. Ladle in the hot tomatoes, leaving 1/2 to 3/4 inch of headspace in each jar. Wipe the rims, set on the lids, and screw on the bands fingertip tight.
  • Place the jars in a boiling water bath and add enough water to cover the jars by 3 inches. Process the tomatoes for 40 minutes, making sure that the jars are covered with at least 1 inch of water the whole time. If the jars are not covered by water at any point, you have to delete the time that the cans were not totally submerged, add water, bring back to a boil, and begin timing again, deducting any time in which the jars were not submerged.
  • When you remove the tomatoes from the boiling water bath, if some pulp fizzes out of the jars, don't panic; they will probably still seal.
  • Let the jars sit, undisturbed, for at least 12 hours before checking seals. It is important to let them sit undisturbed for 12 hours because the sealing compound on the lids is still cooling and hardening, completing the seal. While the jars cool, you will hear a "plink" type sound from each jar - this is the jars completing the vacuum seal as the final air escapes the jar. After 12 hours have passed, remove the bands and check the lids - press down in the center of the lid. If you cannot push the lid down any further, the jar is sealed. If the lid "gives" a bit, and you can push it down, the jar did not seal. If any jars did not seal, place them in the fridge and use within a week.