Reviewed June 2003

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Quality for Keeps: Tantalizing Tomatoes -- How to Can Fresh Tomato Products

Department of Food Science and Human Nutrition

Quality keepsSelect only disease-free, firm fruit for canning; vine-ripened is best. Do not can tomatoes from dead or frost-killed vines. Use a pressure canner for higher-quality, more nutritious tomato products.

Tomatoes used to be considered an acid food, but some of today's varieties are low-acid. To safely can tomato sauce or whole, crushed or juiced tomatoes, you need to add acid whether you are using a boiling water canner or a pressure canner. Use 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid per quart of tomatoes. For pints, use 1 tablespoon of bottled lemon juice or 1/4 teaspoon citric acid.

You may use vinegar (4 tablespoons of 5 percent vinegar per quart) instead of lemon juice or citric acid. However, vinegar may cause undesirable flavor changes. Add sugar, if desired, to offset an acid taste.

Carefully follow the directions in this guide when canning tomatoes to prevent the growth of Clostridium botulinum, the bacterium that causes botulism food poisoning.

Note
If Clostridium botulinum bacteria survive and grow inside a sealed jar of food, they can produce a poisonous toxin. Even a taste of food containing this toxin can be fatal. Please refer to MU publication GH1451, Steps to Success in Home Canning, for information on correct canning procedure and for the steps to follow in boiling-water and pressure canning.

Spaghetti sauce

Yield
About 9 pints

Quantities of fresh tomatoes needed for spaghetti sauce1

Procedure without meat
Do not increase the proportion of onions, garlic, peppers or mushrooms. Wash tomatoes and dip in boiling water for 30 seconds to 60 seconds or until skins split. Dip in cold water, slip off skins, remove cores and quarter tomatoes. Boil 20 minutes, uncovered, in a large saucepan. Press tomatoes through a food mill or sieve.

Saute onions, garlic, celery or peppers and mushrooms (if desired) in vegetable oil until tender. Combine sauteed vegetables and tomatoes and add remainder of spices, canning salt and sugar. Bring to a boil. Lower heat and simmer, uncovered, until thick enough for serving or until volume is reduced by one-half. Stir frequently to avoid burning. Fill jars; leave 1-inch headspace.

Adjust lids

Procedure for making sauce with meat
Brown 2-1/2 pounds of ground beef or Italian sausage. Drain well. Using the recipe for making sauce without meat, add the specified quantities for garlic, onion, celery or green pepper and mushrooms. Cook until vegetables are tender. Combine browned meat, vegetables and tomatoes. Then follow the directions above for making sauce without meat.

Whole, halved or crushed tomatoes

Quantities of fresh tomatoes needed for whole, halved or crushed tomatoes1

Procedure for whole or halved tomatoes packed in water
Wash tomatoes and dip in boiling water for 30 seconds to 60 seconds or until skins split. Dip in cold water, slip off skins and remove cores. Leave whole or halve. Add bottled lemon juice or citric acid to jars using directions above.

Adjust lids

Procedure for whole or halved tomatoes packed with tomato juice or filled without added liquid
Prepare, peel and acidify tomatoes as described for tomatoes packed in water.

Hot pack
Bring tomatoes to a boil in tomato juice, and boil gently five minutes. Add 1 teaspoon canning salt per quart, if desired. Fill jars with hot tomatoes and cover with hot juice; leave 1/2-inch headspace.

Raw pack
Fill jars with raw tomatoes; leave 1/2-inch headspace. Add 1 teaspoon canning salt per quart if desired. Press tomatoes until spaces fill with juice; leave 1/2-inch headspace.

Adjust lids

Procedure for crushed tomatoes
Wash tomatoes and dip in boiling water for 30 seconds to 60 seconds or until skins split. Dip in cold water, slip off skins and remove cores. Trim off any bruised or discolored portions and quarter. Heat quarters quickly in a large pot; stir to prevent burning. Boil gently five minutes. Add bottled lemon juice or citric acid to jars using directions given above. Add 1 teaspoon canning salt per quart if desired. Fill jars immediately with quartered hot tomatoes; leave 1/2-inch headspace.

Adjust lids

Mexican tomato sauce

Yield
About 7 quarts

Quantities of fresh tomatoes needed for Mexican tomato sauce1

Procedure
Wear rubber gloves while handling chilies or wash hands thoroughly with soap and water before touching your face. Boil peppers 1 minute to 2 minutes in water to blister skins. Cool and slip off skins. Discard seeds and chop peppers.

Wash tomatoes and dip in boiling water for 30 seconds to 60 seconds or until skins split. Dip in cold water, slip off skins and remove cores. Coarsely chop tomatoes and combine chopped peppers and remaining ingredients in a large saucepan.

Bring to a boil. Cover. Lower heat and simmer 10 minutes. Fill jars; leave 1-inch headspace.

Adjust lids

Tomato juice

Quantities of fresh tomatoes needed for tomato juice1

Procedure
Wash and remove stems. If tomatoes are bruised, set them aside and use in freezer products. To prevent juice from separating, quickly cut about 1 pound of fruit into quarters and put directly into saucepan. Heat immediately to boiling while crushing. Continue to slowly add and crush freshly cut tomato quarters to the boiling mixture. Make sure the mixture boils constantly and vigorously while you add the remaining tomatoes. Lower heat and simmer five minutes after adding all tomatoes.

If you are not concerned about juice separation, simply slice or quarter tomatoes into a large saucepan. Crush, heat and simmer for five minutes before juicing.

Press both types of heated tomatoes through a sieve or food mill to remove skins and seeds. Add bottled lemon juice or citric acid to jars using directions at beginning. Reheat juice to boiling. Add 1 teaspoon canning salt per quart if desired. Fill jars with hot tomato juice; leave 1/2-inch headspace.

Adjust lids

Tomato ketchup

Yield
6 pints to 7 pints

Quantities of fresh tomatoes needed for tomato ketchup1

Procedure
Wash tomatoes. Dip in boiling water for 30 seconds to 60 seconds or until skins split. Dip in cold water. Slip off skins, and remove cores. Quarter tomatoes into a 4-gallon stock pot or a large kettle. Add onions and red peppers. Bring to a boil, lower heat and simmer uncovered for 20 minutes.

Combine spices in a spice bag, place in a 2-quart saucepan and add vinegar. Bring to a boil, cover and turn off heat. Let stand 20 minutes. Remove spice bag and combine vinegar and tomato mixture. Boil about 30 minutes. Put boiled mixture through a food mill or sieve. Return juice to pot. Add sugar and canning salt, boil gently and stir frequently until volume is reduced by one-half or until mixture rounds up on spoon without separation. Fill pint jars; leave 1/8-inch headspace.

Adjust lids

Tomato sauce

Quantities of fresh tomatoes needed for thick tomato sauce1

Quantities of fresh tomatoes needed for thin tomato sauce1

Procedure
Wash, remove stems and trim off discolored portions. If bruised, set these tomatoes aside for freezer products. To prevent sauce from separating, quickly cut about 1 pound of tomatoes into quarters and put directly into saucepan. Heat immediately to boiling while crushing. Continue to slowly add and crush freshly cut tomato quarters to the boiling mixture. Make sure the mixture boils constantly and vigorously while you add remaining tomatoes. Lower heat and simmer five minutes after all tomatoes are added.

If you are not concerned about sauce separating, simply slice or quarter tomatoes into a large saucepan. Crush, heat and simmer for five minutes before pressing.

Press either type of heated tomatoes through a sieve or food mill to remove skins and seeds. Heat tomatoes again to boiling. Lower heat and simmer in a large saucepan until sauce reaches desired consistency. Simmer until volume is reduced by one-third for thin sauce, or by one-half for thick sauce. Add bottled lemon juice or citric acid to jars using directions at beginning. Add 1 teaspoon canning salt to each quart jar if desired. Fill jars; leave 1/4-inch headspace.

Adjust lids

For best quality and nutritional value, use home-canned tomato products within one year.

1These are general guidelines. See recipes for exact amounts.
2This time is safe at altitudes up to 6,000 feet.
3Hot pack is preferable for quality and safety.

GH1456, reviewed June 2003