The tomato canning process includes coring, boiling the tomatoes, removing the skin and putting the tomatoes in jars to seal. Sealing the jars typically requires boiling the tomatoes, but a dedicated pressure canner can be used instead.
The skin is easy to remove after the tomatoes are submerged in ice water after boiling. During this step, remove any unwanted pieces, including skins, cores, tough spots and blemishes on the fruit. Tomatoes may be kept hole, pureed or diced before canning. Afterward, load the tomatoes directly into sterilized jars, stew to add seasoning and texture or add to the jars with seasonings. Sterilize the jars by boiling in water or running them through a hot dishwasher.
Once the tomatoes are in the jars, pour in 2 tablespoons of lemon or lime juice for quart jars, or 1 tablespoon per pint, to add acidity. This preserves the color, texture and flavor of the tomatoes after canning. Fill the rest of the jar with tomato juice or boiling water until only 1/2 inch of air is left.
After the lids are secured, submerge the filled jars in boiling water to complete the sealing process. Depending on the size of the jars and the altitude, up to 60 minutes in the boiling water may be required.