Tomatoes bring a fresh, tangy taste to a wide variety of home food preservation products and can be safely canned, frozen, or dehydrated to keep that fresh flavor to enjoy later in the year. Popular preserved tomato products include salsa, sauces, and tomato juice in addition to tomatoes preserved whole or halved for cooking use later.
Processing Tomatoes
Select Quality Tomatoes
Preserved tomatoes taste best when the process begins with good-quality produce. Choose firm, disease-free, ripe, or under-ripe tomatoes. Cherry and grape tomatoes are not recommended for canning. Overripe tomatoes are too low in acid to safely can. Green, under-ripe tomatoes, or heirloom tomatoes may be used following the same directions as ripe, red tomatoes.
Do not can tomatoes from dead or frost-killed vines, as they may be too low in acid. Freeze or dehydrate instead.
Remove Tomato Skins
Most recipes for canned, frozen, or dried preserved tomato products will call for peeled tomatoes. Canning recipes that call for it must use peeled tomatoes, as the processing time for the recipe is based on a peeled tomato.
- Wash tomatoes under cool running water.
- Use a paring knife to cut a small "X" on the bottom or the tomato; this will help
- Dip tomatoes in boiling water for 30 to 60 seconds to loosen the skin. Avoid leaving tomatoes in boiling water too long; they will become mushy.
- Remove tomatoes from boiling water and dip them in a bowl of ice water to cool them quickly.
- Slip off the skin and remove the core.
Process the peeled and cored tomatoes according to the recipe. Some recipes will call specifically for whole, halved, or chopped tomatoes. Others may require further processing or milling to remove seeds.
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Canning Tomatoes
All tomato products intended for canning require added acid to ensure a safe pH level of the final product. Previously frozen tomatoes can be made into sauces or juice and then canned. Using frozen tomatoes to make and can salsa is not recommended as freezing significantly changes the tomato texture.
Adding Acid to Tomato-Based Products
Due to the many varieties of tomatoes and the uncertainty of their acidity level, acid must be added to tomatoes, even when pressure canning. Choose one acidifier option to add to each canning jar before adding the tomatoes and liquid.
| Form of Acid | Amount per Pint | Amount per Quart |
|---|---|---|
| Bottled lemon juice | 1 Tablespoon | 2 Tablespoons |
| Citric acid | ¼ teaspoon | ½ teaspoon |
| *Vinegar | 2 Tablespoons | 4 Tablespoons |
*Vinegar may have an undesirable flavor.
Acid Adjustments
- Do not alter the amount of acid called for in a tested recipe.
- It is safe to substitute bottled lime or bottled lemon juice for a tested recipe that calls for 5% vinegar.
- Do not use fresh lemon juice or fresh lime juice as acidity levels can vary.
- Do not use key lime juice in any form (bottled or fresh); key limes have different acidity than regular limes.
- Do not substitute 5% vinegar if a tested recipe calls for bottled lemon or bottled lime juice.
Adding Salt
Salt is used for flavor only, not to prevent spoilage.
| Ingredient | Amount per Pint | Amount per Quart |
|---|---|---|
| Salt (optional) | ½ teaspoon | 1 teaspoon |
Canning Methods
Tomato products, including salsa and sauces, and ripe, under-ripe, or green tomatoes can be canned safely either using a pressure canner or boiling-water bath canner. Tomato products can be safely canned using either method, but if the recipe provides directions only for the pressure canning method, use only that method.
Boiling-water Bath Canning
This method is used for canning acidic or borderline acidic foods such as tomatoes and figs with added acid; fruits, jams, and jellies; pickled products; and fermented products. Water bath canning uses a pot of boiling water that can reach 212 F maximum, no matter how long the product processes. Use jar sizes recommended by the tested recipe and follow the recipe's processing times.
Pressure Canning
This canning method must be used when processing low-acid foods, such as meats, vegetables, broth, snap and dried beans, and mixed products. The steam produced inside of a sealed and properly weighted canner lets the processed product reach the high temperature of 240 F. needed to destroy bacteria spores that can cause C. botulinum.
Packing Tomatoes
Raw Pack with No Added Liquid
To pack whole or halved tomatoes raw without any added liquid, wash the tomatoes, remove skins, and core. Add the appropriate amount of acid to the jars. Press the peeled and cored tomatoes into jars until the remaining space between tomatoes fills up with the juice released from the pressed tomatoes. Leave ½-inch headspace between the product and the rim of the jar. Remove air bubbles, wipe rims with a damp paper towel or cloth, and add lids. Follow the processing directions below for altitudes between 0 to 1,000 feet elevation.
| Boiling Water Bath | Pressure Canner (Dial Gauge = 11 lbs. and Weighted Gauge = 10 lbs.) | |
|---|---|---|
| Pints or Quarts | 85 minutes | 25 minutes |
Tomatoes Packed in Water (Raw or Hot)
To pack whole or halved tomatoes (raw or hot) in water, wash the tomatoes, remove skins, and core.
- Raw pack: Pack tomatoes tightly in jars. Fill the jar with boiling water, leaving ½ inch headspace.
- Hot pack: In a saucepan, cover the peeled and cored tomatoes with water and gently boil for 5 minutes. Pack tomatoes and liquid in jars, leaving ½ inch headspace.
Remove air bubbles, wipe rims with a damp paper towel or cloth, and add lids. Follow processing directions below for altitudes between 0 to 1,000 feet elevation.
| Jar Size | Boiling Water Bath | Pressure Canner (Dial Gauge = 11 lbs. and Weighted Gauge = 10 lbs.) |
|---|---|---|
| Pints | 40 minutes | 10 minutes |
| Quarts | 45 minutes | 10 minutes |
Tomatoes Packed in Tomato Juice (Raw or Hot)
To pack whole or halved tomatoes (raw or hot) in tomato juice, wash the tomatoes, remove skins, and core.
- Raw pack: Pack tomatoes tightly in jars. Fill the jar with heated tomato juice, leaving ½ inch headspace.
- Hot pack: In a saucepan, cover the peeled and cored tomatoes with juice and gently boil for 5 minutes. Pack tomatoes and liquid in jars, leaving ½ inch headspace.
Remove air bubbles, wipe rims with a damp paper towel or cloth, and add lids. Follow processing directions below for altitudes between 0 to 1,000 feet elevation.
| Jar Size | Boiling Water Bath | Pressure Canner (Dial Gauge = 11 lbs. and Weighted Gauge = 10 lbs.) |
|---|---|---|
| Pints or Quarts | 85 minutes | 25 minutes |
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Freezing Tomatoes
Freezing tomatoes takes less time than canning and rrequires less equipment. Tomatoes and tomato products which will be frozen do not need to be acidified, and It is not necessary to remove tomato skins before freezing, although many people prefer them without skins. Also, unlike most vegetables, tomatoes do not have to be blanched before freezing.
Containers for Freezing
Use freezer-safe containers made with plastic or glass, such as plastic freezer containers with tight-fitting lids or wide-mouth canning jars. Do not use regular glass jars; they break easily at freezer temperatures. Plastic freezer bags are another suitable option. Press to remove as much air as possible before closing. Before freezing, label the wrapping or airtight container with the product name, current date, and recommended storage time. For best quality, use frozen tomatoes within 10 to 12 months. However, they will remain safe after that.
Freezing Raw Tomatoes
- Wash, remove skins and core; leave whole or in pieces.
- Pack into freezer containers or freezer-safe plastic bags, leaving 1 inch of headspace.
- Seal, label, and freeze.
Freezing Tomato Juice and Mixtures
- Prepare product according to recipe (may use a canning recipe).
- Cool and pour into freezer containers, leaving appropriate headspace:
- Narrow-mouth canning jars: 1-½ inch of headspace.
- Wide mouth canning jars: ½ to 1 inch of headspace.
- Seal, label, and freeze.
Freezing Other Tomato Variations
- Stewed tomatoes: Simmer in water for 10 to 20 minutes.
- Green tomatoes (for fried green tomatoes): Wash and dry. Leave skins on and slice.
- Cherry or grape tomatoes: Roast with olive oil in a 450 F oven for 20 to 25 minutes until they blister and split.
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Drying Tomatoes
Dehydrated tomatoes are packed with flavor! Thick-walled paste-type tomatoes work well for drying. Good choices for drying are Roma or Italian-type plum tomatoes, other paste tomatoes, or grape and cherry tomatoes.
Drying Methods
In Illinois, electric dehydrators or an oven are the only two methods recommended for drying tomatoes. Outdoor home drying is not recommended for meats or vegetables, including tomatoes. After dehydrating, test for doneness. Dry tomatoes until they are slightly pliable. If they feel sticky to the touch, they need more time to dry. Make sure to turn tomatoes and rotate racks.
Electric Dehydrator
Dehydrators are designed to dry foods fast, maintain a temperature of 140 F., and circulate air with a built-in fan.
Directions
- Wash tomatoes, remove skins, and core. Cherry and grape tomatoes do not require skin removal.
- Slice tomatoes into ¼ to ½-inch thick slices, or halve or quarter.
- Place on drying trays, leaving ½-inch of space between tomatoes.
- Dry in a dehydrator at 140 F for 10 to 18 hours, turning tomatoes and rotating racks as needed.
Oven
Oven drying takes two to three times longer than drying in an electric dehydrator. Make sure the oven can hold a temperature of 140 F.
Directions
- Wash tomatoes, remove skins, and core. Cherry or grape tomatoes do not require skin removal.
- Slice tomatoes into ¼ to ½-inch thick slices, or halve or quarter.
- Place on drying trays, leaving ½-inch of space between tomatoes.
- Prop open the oven door 2 to 6 inches to allow air circulation. Take caution: this can be dangerous for small children or pets.