Here’s how to can whole tomatoes the safe way.

By Corey Williams
August 11, 2020
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It’s easier than you think to can tomatoes at home, but you have to know what you’re doing. Eating improperly canned tomatoes can cause serious illness and even death. Here’s what you need to know: 

How Long Do Canned Tomatoes Last? 

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Properly canned tomatoes will be safe to eat for years, though you’ll probably get the best flavor and texture in the first 365 days. 

Of course, it’s important to recognize that canned food does eventually go bad—and home-canned goods don’t come with an expiration date printed on the label. That means you need to use your common sense here: If you open the jar 15 months down the road and your tomatoes look or smell weird, please don’t eat them. 

Dangers of Canned Tomatoes

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Home-canned vegetables are the most common cause of botulism outbreaks in the United States. 

Botulism is a serious illness caused by a toxin that can cause difficulty breathing, paralysis, and death.

“You cannot see, smell, or taste botulinum toxin–but taking even a small taste of food containing this toxin can be deadly,” according to the USDA

The USDA recommends boiling home-canned tomatoes in a saucepan before you eat them, even if you detect no signs of spoilage. 

When in doubt, always throw it out. If you suspect your home-canned goods may be contaminated, dispose of them properly.

What You’ll Need 

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Tomatoes (any tomatoes will do, but plum varieties work best) 

How to Can Tomatoes

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    Step 1: Blanch and Peel 

    Blanch the tomatoes before you do anything else. This makes them easier to peel. To blanch: Wash tomatoes and cut a small X into the bottom of each one. Using a slotted spoon, submerge tomatoes one-by-one in boiling water for about 30 seconds each. Immediately transfer to an ice bath to stop the cooking process, then place in a colander to drain. 

    Once you’ve blanched all the tomatoes, you should be able to easily slip off the skins (start at the X and pull away). 

    Step 2: Sterilize Jars

    Place your jars (without lids) on the canning rack and submerge in the still-boiling water. Boil for 10 minutes to sterilize them. Put the lids in separately and boil those for 10 minutes as well. Remove the jars and pour any water remaining in them back into the pot. Bring the pot back to a boil. 

    Step 3: Canning and Processing

    1. Pour citric acid, or lemon juice, into each jar before adding water or tomatoes. This is an important safety measure you absolutely can’t skip. According to The Old Farmer’s Almanac, you should use 2 tablespoons lemon juice if you’re using quart-sized jars and 1 tablespoon if you’re using pint-sized jars. 
    2. Fill the jars with the peeled tomatoes and ladle the hot water over them until the tomatoes are submerged and the jar is almost full, about ½ an inch from the top. Use a funnel to add the water to the jars to prevent burns. Thoroughly wipe the rims (this is essential—leftover food particles could keep them from completely sealing) and tightly seal the jars with the sterilized lids. 
    3. Place the full jars back onto the canning rack and submerge, with at least an inch of water above the jars, in boiling water once again. Cover and cook for about 45 minutes. Make sure to keep an eye on the pot during this process. As the boiling water produces steam, you may need to refill the pot to keep the jars fully submerged throughout processing. 
    4. Carefully remove the lid, venting the steam away from your body. Lift the canning rack and, with a kitchen towel or oven mitt, gently remove each jar and let dry in a relatively warm place. If the temperature is too cool in your kitchen, the shock may cause the jars to break. 
    5. Once cool and dry, store your canned tomatoes in a cool, dark place until you’re ready to use them.