Fact Sheet 9.341 by M. Bunning, E. Shackelton, and P. Kendall* (1/23)
Home canning is a great way to preserve tomatoes for later use. Using tested methods and recipes, choice ingredients, and having an awareness of acidity levels are critical to a safe home-canned product.
- The canning processes recommended in this fact sheet are the result of USDA research on safe home-canning procedures for tomatoes and tomato products.
- The processing times stated in these recipes are designed to ensure destruction of microorganisms. Where appropriate, processing recommendations for both boiling water canners and pressure canners are given. Using a pressure canner generally results in higher quality canned tomato products.
Quick Facts…
- Select fresh, undamaged, vine-ripened tomatoes for canning. Avoid overripe tomatoes.
- To ensure safety, acid must be added when home canning whole, crushed or juiced tomatoes.
- Freezing is a safe, easy alternative to home canning. Frozen tomatoes and tomato products do not need added acid.
- Use CSU Extension’s free Preserve Smart app/website for 24/7 access to tested home food preservation recipes and instructions of over 55 fruits and vegetables!
Tomato Acidity
Although tomatoes are traditionally considered a high-acid food (pH below 4.6), certain environmental conditions and varieties can yield tomatoes and tomato products with pH values above 4.6. Because of this uncertainty, home-preserved tomato products must be either (1) processed as a low-acid food using a pressure canner, or (2) acidified to a pH of 4.6 or below (using lemon juice or citric acid) and processed using a boiling water canner.
Several conditions can reduce the acidity of tomatoes. These include:
- Tomatoes with decay or damage caused by bruises, cracks, blossom end rot or insects
- Tomatoes grown in the shade, ripened in shorter hours of daylight, ripened off the vine (compared to those ripened in direct sunlight on the vine), or over-ripened
- Tomatoes attached to dead vines at harvest (compared to 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 canner.
- Acid can be added directly to the jars before filling with product.
- For quarts: add 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid.
- For pints: add 1 tablespoon bottled lemon juice or 1/4 teaspoon citric acid.
- NOTE: 4 tablespoons of a 5 percent acidity vinegar per quart (2 tablespoons per pint) can be used instead of lemon juice or citric acid. However, vinegar may cause undesirable flavor changes.
- Add sugar to offset the vinegar taste, if desired.
Process Tomatoes Carefully to Avoid Spoilage
The most common reasons for spoilage in home-canned tomato products are under-processing and failed seals. Tomatoes that have not been processed long enough to destroy heat-resistant bacteria and fungi (molds) may spoil during storage.
- Thermophilic (heat-loving) spoilage organisms are heat resistant and may cause 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 bacteria in the product.
- Never use canned tomatoes or tomato juices with off-odors!
- Molds can also 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 safely where they cannot be eaten by other people or animals.
- Following the directions and processing times stated in this fact sheet will ensure sufficient destruction of bacteria and fungi.
Prepare Jars and Equipment
Canning Jars
- Use standard mason jars designed specifically for home canning.
- Discard any jars with cracks or chips since defects can prevent an airtight seal or failure during the canning process.
- Wash jars in hot, soapy water and rinse well before using.
- Do not use commercial food jars (mayonnaise, pasta sauce, etc.) as they are not heat-tempered and can break easily and/or not seal properly when processed.
Lids and Screw Bands (two-piece set)
- Discard any screw bands with dents or rust, since defects can prevent an airtight seal.
- Prepare new/unused flat metal lids as directed by the manufacturer.
- Lids are designed for single-use, and should NOT be used for home canning more than once!
- Screw bands can be cleaned and used multiple times. Store carefully to prevent rusting or denting.
NOTE: One-piece home canning lids have not been researched for safe home food preservation, and are therefore not recommended.
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.
- Contact your nearest Colorado State University Extension county office to have your dial gauge and lid checked annually.
- Use a pressure canner designed for home canning that holds at least 4, 1-quart jars.
- Stovetop pressure cookers are not designed to be used for home canning.
- Electric multi-cookers should also NOT be used for home food preservation because they cannot ensure adequate temperature and heat penetration within the jars to destroy harmful bacteria.
Boiling water canner
Any large metal pan may be used as a boiling water canner if it is deep enough, has a tight-fitting cover, and has a rack that fits inside to elevate the jars slightly off the bottom of the canner.
- A rack divider is also recommended to prevent jars from touching each other or falling against the side of the canner during processing.
- 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 canner.
- Cover but do not fasten the lid.
- Leave the petcock wide open so steam can escape and pressure does not build up inside the canner.
Other Useful Canning Tools:
- Air bubble remover, plastic knife, or non-metallic spatula- used to release air bubbles from within the jar
- Canning funnel- funnel made from metal or food- grade plastic with wide, short neck for filling jars
- Headspace ruler- special graduated utensil or plastic ruler for measuring required space at the top of a filled jar
- Jar lifter- used to safely move jars to and from hot water during the canning process
- Magnetic lid wand- helps transfer metal lids to top of jars and prevent contamination
- Timer- necessary for critical timed steps throughout the canning process
Prepare Tomatoes
Select fresh, firm, ripe tomatoes.
- Do not can soft, over-ripe, moldy or decayed tomatoes or tomatoes harvested from dead or frost-killed vines.
- Approximately 2 1/2 to 3 1/2 pounds of fresh tomatoes makes 1 quart of canned tomatoes.
Wash, peel, and trim tomatoes.
- Rinse tomatoes under running water to clean.
- To remove skins, dip in boiling water for 30 to 60 seconds or until the skins split. Transfer to container containing ice cold water.
- Use a sharp knife to peel off the skin, cut out the core, and trim away any bruised or discolored portions.
Fill Jars and Process
Fill jars according to the processing method (raw or hot pack) 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 lid on the jar. Turn the screwband fingertip tight.
The jars are now ready to process in a boiling water or pressure canner as described in Table 1.
Test Seals
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.
- If sealed, remove screwbands. Label sealed jars with contents, canning method and date. Store in a clean, cool, dry, dark place.
- If not sealed, the product must be reprocessed, refrigerated, or frozen immediately.
Reprocessing
VERY IMPORTANT: Treat any jars that failed to seal as perishable (not shelf-stable).
- The food should either be eaten immediately, refrigerated, frozen, or reprocessed.
- The food can be safely reprocessed within 24 hours after the first processing.
- You must repeat the entire canning process, using a new lid to ensure a safe product.
- To reprocess, remove lids and empty the food and liquid into a pan. Cover and heat to boiling. Pack into clean, hot jars. Put on new pre-treated lids. Process again for the full time specified in recipe.
If you notice unsealed jars more than 24 hours after processing, it is not safe to reprocess the jars. Destroy the contents!
Table 1: Processing directions for canning tomatoes and tomato products in a boiling water canner or pressure canner.
| 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. -When 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: |
||||||
|---|---|---|---|---|---|---|
| *Weighted Gauge Pressure Canner: | ||||||
| 0-1000 feet, process at 10 pounds pressure | ||||||
| 1001-10,000 feet, process at 15 pounds pressure | ||||||
| *Dial Gauge Pressure Canner: | ||||||
| 0-2000 feet, process at 11 pounds pressure | ||||||
| 2001-4000 feet, process at 12 pounds pressure | ||||||
| 4001-6000 feet, process at 13 pounds pressure | ||||||
| 6001-8000 feet, process at 14 pounds pressure | ||||||
| 8001-10,000 feet, process at 15 pounds pressure |
Table 1: Directions for canning tomatoes and tomato products in a boiling water canner or pressure canner
| Product | Procedure/Processing Method | Jar Size | Processing Time (in minutes) 1001'-3000' | Processing Time (in minutes) 3001'-6000' | Processing Time (in minutes) 6001'-8000' | Processing Time (in minutes) 8001'-10,000' | |
|---|---|---|---|---|---|---|---|
| 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 canner 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 has been reached. | |||||||
| Tomato Juice | An 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 Canner | pints | 40 | 45 | 50 | 55 | ||
| quarts | 45 | 50 | 55 | 60 | |||
| Pressure Canner* | pints or quarts | 15 | 15 | 15 | 15 | ||
| 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 Canner | pints | 40 | 45 | 50 | 55 | ||
| quarts | 45 | 50 | 55 | 60 | |||
| Pressure Canner* | pints or quarts | 15 | 15 | 15 | 15 | ||
| 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 Canner | pints | 40 | 45 | 50 | 55 | ||
| quarts | 50 | 55 | 60 | 65 | |||
| Pressure Canner* | pints or quarts | 15 | 15 | 15 | 15 | ||
| Standard Tomato Sauce | For 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 Canner | pints | 40 | 45 | 50 | 55 | ||
| quarts | 45 | 50 | 55 | 60 | |||
| Pressure Canner* | pints or quarts | 15 | 15 | 15 | 15 | ||
| 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 Canner | pints | 45 | 50 | 55 | 60 | ||
| quarts | 50 | 55 | 60 | 65 | |||
| Pressure Canner* | pints or quarts | 10 | 10 | 10 | 10 | ||
| 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 Canner | pints or quarts | 90 | 95 | 100 | 105 | ||
| Pressure Canner* | pints or quarts | 25 | 25 | 25 | 25 | ||
| 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 Canner | pints or quarts | Not recommended | Not recommended | Not recommended | Not recommended | ||
| Pressure Canner* | pints | 30 | 30 | 30 | 30 | ||
| quarts | 35 | 35 | 35 | 35 | |||
| Spaghetti Sauce | Wash, 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, quartered •4 1/2 teaspoons salt | •1 lb. fresh mushrooms, sliced •2 tablespoons oregano | •1 cup onions, chopped •4 tablespoons parsley, minced | •5 cloves garlic, minced •2 teaspoons black pepper | •1 cup celery or green pepper, chopped •1/4 cup brown sugar | For recipe with meat: Add 2 1/2 lbs. ground beef or sausage For recipe without meat: Add 1/4 cup vegetable oil | |
| Boiling Water Canner | pints or quarts | Not recommended | Not recommended | Not recommended | Not recommended | ||
| Pressure Canner* | pints | 60 | 60 | 60 | 60 | ||
| quarts | 70 | 70 | 70 | 70 | |||
| 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 Canner | pints or quarts | Not recommended | Not recommended | Not recommended | Not recommended | ||
| Pressure Canner* | pints | 20 | 20 | 20 | 20 | ||
| quarts | 25 | 25 | 25 | 25 | |||
| Mexican Tomato Sauce | Prepare 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. chili peppers, peeled and chopped | •18 lbs. tomatoes, peeled and chopped | •3 cups onions, chopped | •1 tablespoon salt | •1 tablespoon oregano | •1/2 cup vinegar (5% acidity) | |
| Boiling Water Canner | pints or quarts | Not recommended | Not recommended | Not recommended | Not recommended | ||
| Pressure Canner* | pints | 20 | 20 | 20 | 20 | ||
| quarts | 25 | 25 | 25 | 25 | |||
| Tomato Catsup | 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 tablespoons celery seeds | •3 cups onions, chopped •3 cups cider vinegar (5%) | •3/4 teaspoon ground red pepper •1 1/2 cups sugar | •4 teaspoons whole cloves •1/4 cup salt | •3 sticks cinnamon, crushed | •1 1/2 teaspoons whole allspice | |
| Boiling Water Canner | pints and half pints | 20 | 20 | 25 | 25 | ||
| Pressure Canner* | Not recommended | Not recommeded | Not recommended | Not recommended | |||
| 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 and chopped | •2 lbs. chili peppers, peeled and chopped | •1 lb. onions, chopped | •1 cup vinegar (5% acidity) | •3 teaspoons salt | •1/2 teaspoon black pepper | |
| Boiling Water Canner | pints and half pints | 20 | 20 | 25 | 25 | ||
| Pressure Canner* | Not recommended | Not recommeded | Not recommended | Not recommended | |||
Reference
National Center for Home Food Preservation https://nchfp.uga.edu/
USDA Complete Guide to Home Canning. Agriculture Information Bulletin No. 539. U.S. Department of Agriculture, National Institute of Food and Agriculture. 2015. Available at: https://nchfp.uga.edu/how/can/how-do-i-can-tomatoes/canning-tomatoes-introduction/
*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.
