Canning Tomatoes and Tomato Products

by P. Kendall* (5/12)

Quick Facts…

  • Select disease-free, preferably vine-ripened, firm tomatoes for canning. Avoid overripe tomatoes.
  • To ensure safe acidity in whole, crushed or juiced tomatoes, add 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid per quart of tomatoes. For pints, add 1 tablespoon bottled lemon juice or 1/4 teaspoon citric acid.
  • Freezing is a safe, easy alternative to home canning. Frozen tomatoes and tomato products do not need added acid.

Tomatoes are the most widely homecanned product in the United States. They also are one of the most commonly spoiled home-canned products. The canning processes recommended in this fact sheet are the result of USDA research on safe home-canning procedures for tomatoes and tomato products.

Tomato Acidity

Although tomatoes are considered a high-acid food (pH below 4.6), certain conditions and varieties can produce tomatoes and tomato products with pH values above 4.6. When this happens, the product must be canned in a pressure canner as a low-acid product or acidified to a pH of 4.6 or lower with lemon juice or citric acid.

Research has found several conditions that can reduce the acidity of tomatoes. These include decay or damage caused by bruises, cracks, blossom end rot or insects, and overripening. Tomatoes grown in the shade, ripened in shorter hours of daylight, or ripened off the vine tend to be lower in acidity than those ripened in direct sunlight on the vine. Also, tomatoes attached to dead vines at harvest are considerably less acidic than tomatoes harvested from healthy vines. Decayed and damaged tomatoes and those harvested from frost-killed or dead vines should not be home canned.

To ensure safe acidity in whole, crushed or juiced tomatoes, add lemon juice or citric acid when processing in a boiling water bath. Add 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid per quart of tomatoes. For pints, use 1 tablespoon bottled lemon juice or 1/4 teaspoon citric acid. Acid can be added directly to the jars before filling with product. Add sugar to offset the taste, if desired. Four tablespoons of a 5 percent acidity vinegar per quart can be used instead of lemon juice or citric acid. However, vinegar may cause undesirable flavor changes.

Process Carefully to Avoid Spoilage

The most common reasons for spoilage in home-canned tomato products are underprocessing and incomplete seals. Tomatoes that have not been processed long enough to destroy molds and heat-resistant bacteria may spoil during storage. One of the common spoilage organisms, Bacillus coagulans, is very heat resistant and causes flat-sour spoilage. The jar lid may still be sealed and the product may appear normal, but the tomatoes will smell sour because of lactic acid produced by the growth of B. coagulans in the product. Never use tomatoes or tomato juices with off-odors.

Molds can grow on the surface of improperly processed tomato products and may eventually reduce the acidity to a point where botulism-producing spores can grow and produce a deadly toxin. Because even minute amounts of botulism toxin can cause fatal illness, discard without tasting any canned products that show mold growth on the surface. Discard them where they cannot be eaten by other people or animals.

The processing times in this fact sheet are designed to ensure sufficient destruction of bacteria and molds. Where appropriate, processing recommendations for both water bath and pressure canning are given. In general, a pressure canner results in higher quality and more nutritious canned tomato products.

Yield Information
One bushel of fresh tomatoes weighs 53 pounds and yields approximately 18 quarts of canned tomatoes or 15 to 18 quarts of juice. Approximately 2 1/2 to 3 1/2 pounds of fresh tomatoes makes 1 quart of canned tomatoes.

Prepare Jars and Equipment

Standard mason jars are recommended for home canning. Be sure all jars and closures are perfect. Discard any with cracks, chips, dents or rust. Defects prevent airtight seals.

Wash jars in hot, soapy water and rinse well before using. Prepare metal lids as manufacturer directs.

Pressure canner. Make sure your pressure canner has a tight-fitting cover, clean exhaust vent (or petcock) and safety valve, and an accurate pressure gauge. There are two types of pressure gauges: weighted and dial gauges. Weighted gauges need only to be cleaned before using. Dial gauges need to be checked for accuracy. Check them each season before use, more frequently if used often. Ask your Colorado State University Extension county office where to have your gauge checked.

Use a pressure canner that holds at least 4 quart jars. Smaller pressure canner-saucepans are not recommended for home canning as they heat up and cool down too quickly to ensure adequate heat penetration using the processing schedules specified in this fact sheet.

Water bath canner. Any big metal container may be used as a boiling water bath canner if it is deep enough and has a tight-fitting cover and a wire or wooden rack. Rack dividers prevent jars from touching each other or falling against the side of the canner. Be sure the container is at least 4 to 5 inches deeper than the height of jars used to allow adequate space for the rack and briskly boiling water. For pint jars, you need a container at least 10 inches deep. For quart jars, the container should be at least 12 inches deep.

A deep pressure canner may be used as a boiling water bath. Cover but do not fasten the lid. Also, leave the petcock wide open so steam can escape and pressure does not build up inside the canner.

Prepare Tomatoes

Select fresh, firm, ripe tomatoes. Do not can soft, overripe, moldy or decayed tomatoes or tomatoes harvested from dead or frost-killed vines. Green tomatoes are more acidic than ripened tomatoes and can be canned safely with any of the following recommendations.

Wash tomatoes well and drain. Dip in boiling water for 30 to 60 seconds or until the skins split. Then dip in cold water. Use a sharp knife to cut out the stem and all of the white core beneath the stem. Peel off the skin. Trim off any bruised or discolored portions.

Reprocessing Jars of tomatoes or tomato products that do not seal can be safely reprocessed within 24 hours of the initial processing. However, if the jar sealed at first and then unsealed a few days later, spoilage is indicated. Do not reprocess such jars; destroy the contents. To reprocess, remove lids and empty the food and liquid into a pan. Heat to boiling and pack into clean, hot jars. Put on new pretreated lids. Process again for the full time. The quality of twice-processed foods may be lower, with textural changes and additional loss of heat-sensitive nutrients such as vitamin C and B-complex.

Fill Jars and Process

Fill jars according to the pack method described for each product on the following pages. Remove trapped air bubbles by inserting a nonmetallic spatula or knife between the food and the jar. Slowly turn the jar and move the spatula up and down to allow air bubbles to escape. Add more liquid if necessary to obtain the proper headspace (see recipes in Table 1). Wipe the jar rim with a clean, damp paper towel to remove any food particles. Place pretreated lid on the jar. Turn the screwband fingertip tight.

The jars are now ready to process in a boiling water bath or pressure canner as described in Table 1.

After processing, carefully remove jars from canner and place on rack, dry towel or newspaper. Allow jars to cool untouched, away from drafts, for 12 to 24 hours before testing seals. To test jar seals, press flat metal lids at the center of lid. They should be slightly concave and not move. Remove screwbands. Label sealed jars with contents, canning method and date. Store in a clean, cool, dry, dark place.

Table 1: Directions for canning tomatoes and tomato products in a boiling water bath and/or pressure canner.

General directions:
-Approximately 2 1/2 to 3 1/2 pounds of fresh tomatoes yields 1 quart of canned tomatoes.
-Wash, skin and trim tomatoes as described in the 'Prepare Tomatoes' section. Fill jars according to the raw or hot pack method described for each product. Release air bubbles and close jars as described in the 'Fill Jars and Process' section. Process in a boiling water bath or pressure canner as directed by recipe and for your elevation. Begin timing when water returns to boiling (boiling water bath canner) or after pressure canner has been vented for 10 minutes and correct pressure reached.
Elevation Adjustments: The processing times and pressures given are those recommended by the U.S. Department of Agriculture. DO NOT DECREASE the processing times or pressures given. At varying elevations, if a recipe specifies the use of a pressure canner, the following pounds pressure must be reached and maintained throughout the canning process for your elevation:
*In a Weighted Gauge Pressure Canner:
At elevations of 0-1000 feet, process at 10 pounds pressure
At elevations of 1001-10,000 feet, process at 15 pounds pressure
*In a Dial Gauge Pressure Canner:
At elevations of 0-2000 feet, process at 11 pounds pressure
At elevations of 2001-4000 feet, process at 12 pounds pressure
At elevations of 4001-6000 feet, process at 13 pounds pressure
At elevations of 6001-8000 feet, process at 14 pounds pressure
At elevations of 8001-10,000 feet, process at 15 pounds pressure
ProductProcedure & Processing MethodJarsProcessing Time (in min.) at elevations of 1001-3000 ftProcessing Time (in min.) at elevations of 3001-6000 ftProcessing Time (in min.) at elevations of 6001-8000 ftProcessing Time (in min.) at elevations of 8001-10,000 ft
Tomato JuiceAn average of 23 pounds of tomatoes is needed to make 7 quarts; 14 pounds to make 9 pints.
Wash and trim tomatoes. To prevent juice from separating, quickly quarter 1 pound of tomatoes into a large saucepan. Heat immediately to boiling while crushing. Continue to slowly add freshly cut tomato quarters to the boiling mixture and crush. Simmer 5 minutes after all pieces are added. Press juice through a foodmill or sieve to remove skins and seeds. Add 2 tablespoons bottled lemon juice or 1/2 teaspoon citric acid to quart jars. Use half this amount for pints. Add 1 teaspoon salt per quart to jars, if desired. Heat juice again to boiling. Fill jars with hot juice, leaving 1/2-inch headspace. Close jars and process.
Boiling Water Bath pints40455055
quarts45505560
Pressure Canner*pints or quarts15151515
Tomato and Vegetable
Juice Blend
An average of 22 pounds tomatoes is needed to make 7 quarts; 14 pounds to make 9 pints. Add no more than 3 cups of any combination of finely chopped celery, onions, carrots and peppers for each 22 pounds of tomatoes used.
Crush and simmer tomatoes and vegetables as for making tomato juice (see above). Simmer mixture 20 minutes. Press mixture through a foodmill or sieve and continue as described above, also adding lemon juice or citric acid.
Boiling Water Bathpints40455055
quarts45505560
Pressure Canner*pints or quarts15151515
Crushed Tomatoes
(with no added liquid)
An average of 22 pounds tomatoes is needed to make 7 quarts; 14 pounds to make 9 pints.
Prepare and quarter tomatoes. Bring 1/6 of quarters quickly to a boil in a large pot, crushing and stirring to exude the juice. Gradually add remaining quarters, stirring constantly. Boil gently 5 minutes. Add 2 tablespoons bottled lemon juice or 1/2 teaspoon citric acid to quart jars. Use half this amount for pints. Add 1 teaspoon salt per quart to jars, if desired. Fill jars immediately with hot tomatoes, leaving 1/2-inch headspace. Close jars and process.
Boiling Water Bathpints40455055
quarts50556065
Pressure Canner*pints or quarts15151515
Standard Tomato SauceFor thin sauce – An average of 35 pounds tomatoes is needed to make 7 quarts; 21 pounds to make 9 pints.
For thick sauce – An average of 46 pounds is needed to make 7 quarts; 28 pounds to make 9 pints.
Prepare and press tomatoes as for making tomato juice. Simmer in large kettle until sauce reaches desired consistency (volume is reduced by one-third for thin sauce or by one-half for thick sauce). Add 2 tablespoons bottled lemon juice or 1/2 teaspoon citric acid to quart jars. Use half this amount for pints. Add 1 teaspoon salt per quart to jars, if desired. Fill jars with hot sauce, leaving 1/4-inch headspace. Close jars and process.
Boiling Water Bathpints40455055
quarts45505560
Pressure Canner*pints or quarts15151515
Whole or Halved Tomatoes
(packed in water)
An average of 21 pounds tomatoes is needed to make 7 quarts; 13 pounds to make 9 pints.
Wash and peel tomatoes. Leave whole or cut in half. Add 2 tablespoons bottled lemon juice or 1/2 teaspoon citric acid to quart jars. Use half this amount for pints. Add 1 teaspoon salt per quart to jars, if desired.
Hot Pack – Place tomatoes in large saucepan and add enough water to cover. Boil gently for 5 minutes. Fill jars with hot tomatoes and cooking liquid, leaving 1/2-inch headspace. Close jars and process. Raw Pack – Fill prepared jars with raw tomatoes to 1/2 inch of jar tops. Add hot water, adjusting headspace to 1/2 inch. Close jars and process. Processing time is the same for hot and raw pack.
Boiling Water Bathpints45505560
quarts50556065
Pressure Canner*pints or quarts10101010
Whole or Halved Tomatoes
(packed in tomato juice or without added liquid)
An average of 21 pounds tomatoes is needed to make 7 quarts; 13 pounds to make 9 pints.
Wash and peel tomatoes; leave whole or cut in half. Add 2 tablespoons bottled lemon juice or 1/2 teaspoon citric acid to quart jars. Use half this amount for pints. Add 1 teaspoon salt per quart to jars, if desired. Hot Pack — Place tomatoes in large saucepan; add enough tomato juice to cover. Boil gently 5 minutes. Fill jars with hot tomatoes to 1/2 inch of jar tops. Cover tomatoes with hot tomato juice, leaving 1/2-inch headspace. Raw Pack – Fill jars with raw tomatoes to 1/2 inch of jar tops. Cover tomatoes with hot tomato juice or press tomatoes in jars until spaces fill with juice. Leave 1/2-inch headspace. Close jars and process all pack styles for the length of time specified above.
Boiling Water Bathpints or quarts9095100105
Pressure Canner*pints or quarts25252525
Tomatoes with Zucchini
or Okra
Use up to 1 pound of zucchini or okra for every 3 pounds of tomatoes. An average of 12 pounds of tomatoes and 4 pounds of okra or zucchini is needed to make 7 quarts; 7 pounds of tomatoes and 2-1/2 pounds of okra or zucchini to make 9 pints.
Wash, peel and quarter tomatoes. Wash vegetables and slice or cube. Bring tomatoes to a boil and simmer 10 minutes. Add vegetables and boil gently 5 minutes. Add 1 teaspoon of salt per quart to jars, if desired. Fill jars with mixture. Leave 1-inch headspace. Close jars and process. For variation, add 4 or 5 pearl onions or 2 onion slices to each jar.
Boiling Water Bathpints or quartsNot recommendedNot recommendedNot recommendedNot recommended
Pressure Canner*pints30303030
quarts35353535
Spaghetti SauceWash, skin, and trim tomatoes as described in the 'Prepare Tomatoes' section. Follow instructions below for preparing ingredients. Fill jars and release air bubbles as described in the 'Fill Jars and Process' section. Close jars and process.
Spaghetti Sauce With Meat – Prepare tomatoes and boil 20 minutes, uncovered, in large saucepan. Put through a food mill or sieve. Saute meat until brown. Add onions, garlic, celery, green peppers and mushrooms (if desired). Cook until vegetables are tender. Combine with tomato pulp in large saucepan. Add salt, oregano, parsley, pepper and brown sugar. Bring to a boil. Simmer, uncovered, until initial volume is reduced by nearly one-half. Stir frequently to avoid burning. Fill jars, leaving 1-inch headspace.
Close jars and process for times below. Yields 9 pints.
Combine the following ingredients:+30 lbs tomatoes, peeled, quarteredOnly for recipe with meat: +2 1/2 lbs ground beef or sausage+1 cup onions, chopped+5 cloves garlic, minced+1 cup celery or green pepper, chopped+1 lb fresh mushrooms, sliced
+4 1/2 teaspoons salt+2 tablespoons oregano+4 tablespoons parsley, minced+2 teaspoons black pepper+1/4 cup brown sugarOnly for recipe without meat: +1/4 cup vegetable oil
Boiling Water Bathpints or quartsNot recommendedNot recommendedNot recommendedNot recommended
Pressure Canner*pints60606060
quarts70707070
Spaghetti Sauce Without Meat – Follow the above directions, omitting the meat and instead saute the vegetables in 1/4 cup vegetable oil until tender. Yields 9 pints.
Caution! Do not increase the portions of onions, peppers or mushrooms.
Boiling Water Bathpints or quartsNot recommendedNot recommendedNot recommendedNot recommended
Pressure Canner*pints20202020
quarts25252525
Mexican Tomato SaucePrepare ingredients: Wash and dry chiles. Make a small slit in side of peppers for steam to escape. Place in a hot oven or broiler (400 degrees) for 6-8 minutes, turning frequently until skins blister and crack. Place in a pan and cover with a damp cloth for several minutes to cool. Peel off skin starting at stem end and peeling downward. Discard seeds and chop peppers. Wash, peel and coarsely chop tomatoes. Combine with chopped peppers and remaining ingredients in large saucepan. Bring to a boil, cover and simmer 10 minutes. Fill jars, leaving 1-inch headspace. Close jars and process. Yields about 7 quarts.
Caution! Wear rubber gloves while handling chilies or wash hands thoroughly with soap and water before touching your face.
Combine the following ingredients:+2 1/2 to 3 lbs chile peppers, peeled and chopped+18 lbs tomatoes, peeled, chopped+3 cups chopped onions+1 tablespoon salt+1 tablespoon oregano+1/2 cup vinegar (5% acidity)
Boiling Water Bathpints or quartsNot recommendedNot recommendedNot recommendedNot recommended
Pressure Canner*pints20202020
quarts25252525
Tomato
Ketchup
Wash, peel and quarter tomatoes. Combine with chopped onions and red pepper in a 4-gallon stockpot or large kettle. Bring to a boil and simmer 20 minutes. Meanwhile, combine spices in a spice bag. Place with vinegar in a 2-quart saucepan. Bring to a boil and turn off heat. Let stand 20 minutes. Remove spice bag and combine vinegar and tomato mixture. Boil mixture 30 minutes. Press boiled mixture through a food mill or sieve. Return to pot. Add sugar and salt. Boil gently, stirring frequently, until volume is reduced by one-half or mixture rounds up on a spoon without separation. Fill jars, remove air bubbles, and leave 1/8-inch headspace. Close jars and process. Yields 6 to 7 pints.
Combine the following ingredients:+24 lbs ripe tomatoes, peeled, quartered+3 cups onions, chopped+ 3/4 teaspoon ground red pepper+4 teaspoons whole cloves+3 sticks cinnamon, crushed+1 1/2 teaspoons whole allspice
+3 tablespoons celery seeds+ 3 cups cider vinegar (5%)+1 1/2 cups sugar+1/4 cup salt
Boiling Water Bathpints and half pints20202525
Chili Salsa (hot tomato-pepper sauce)Combine prepared tomatoes, peppers, onions, vinegar, salt and pepper in a large saucepan. (See Mexican Tomato Sauce for information on peeling chile peppers.) Heat to a boil and simmer 10 minutes. Fill jars, leaving 1/2-inch headspace. Close jars and process. Yields 6 to 8 pints.
Caution! Wear rubber gloves while handling chilies or wash hands thoroughly with soap and water before touching your face.
Combine the following ingredients:+5 lbs tomatoes, peeled, chopped+2 lbs chile peppers, peeled, chopped+1 lb onions, chopped+1 cup vinegar (5% acidity)+3 teaspoons salt+1/2 teaspoon pepper

Reference

USDA Complete Guide to Home Canning. Agriculture Information Bulletin No. 539. U.S. Department of Agriculture, National Institute of Food and Agriculture. 2009. Available at: http://nchfp.uga.edu/publications/publications_usda.html

*P. Kendall, Ph.D., R.D., Colorado State University, associate dean of research, food science and human nutrition.10/99. Revised 5/12.

Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.