Tomatoes can be preserved by canning, drying, freezing or pickling. They can also be used in creating fruit spreads like jams, jellies and marmalades. Raw tomato products can be kept refrigerated (blow 40º F), but will spoil over time due to bacteria, yeasts and molds. Preserving tomatoes in oil is currently not recommended. Oil may protect botulism organisms trapped in a water droplet. Furthermore, oil may a deleterious effect on lid on gaskets and the at least one manufacturer of home canning lids recommended against it. Select only disease-free, preferably vine-ripened, firm fruit for canning.
On bushel (45 lbs.) of tomatoes will yield 26 to 34 frozen pints and for juice 20 to 28 pints. Frozen tomatoes will have a mushy texture when thawed and are suitable only for cooking. In addition, tomatoes that are frozen raw become watery and develop an off-flavor after a short period in the freezer. Tomatoes that are too ripe for safe canning, but are still sound and free from decay, can safely be frozen.
Raw: Wash and dip the tomatoes into boiling water for 30 seconds to loosen the skins. Core and peel. Freeze whole or in pieces. Pack into containers, leaving 1-inch head space. Seal and freeze.
Juice: Wash, sort and trim firm, vine-ripened tomatoes. Cut the tomatoes in quarter or eighths. Simmer 5 to 10 minutes. Press through a sieve. If desired, season with 1 teaspoon salt to each quart of juice. Pour into the containers, leaving 1½-inch head space. Seal and freeze.
Stewed: Remove the stem ends, and peel and quarter ripe tomatoes. Cover and cook them until tender (10 to 20 minutes). Place the pan containing the tomatoes in cold water to cool. Pack into containers, leaving 1-inch head space. Seal and freeze.
Other:Tomato products, such as sauce, puree, catsup and chili sauce can be frozen. Prepare as usual, cool rapidly, pack into rigid containers leaving head space and freeze.
Processing in a Boiling-Water Canner
Preheat the canner filled halfway with water to 180ºF. Load the closed jars onto the canner rack and lower with the handles, or load one jar at a time with a jar lifter onto the rack in the canner. Add boiling water, if needed, to a level of 1 inch above the jars and add the cover. When the water boils vigorously, reduce the heat to maintain a gentle boil and process the jars of product for the time suggested.
Processing in a Pressure Canner
Pressure canning produces higher quality and more nutritious canned tomato products. Place the jar rack, 2 inches of water and the closed jars in the canner. Fasten the canner lid, and heat the canner on a high setting. After the steam exhausts for 10 minutes, add the weighted gauge or close the petcock to pressurize the canner. Start timing the process when the desired pressure is reached. Regulate the heat to maintain a uniform pressure and process the jars for the suggested time. The products are best if eaten within a year and safe as long as the lids remain vacuum sealed.