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Looking to can your tomatoes before they go bad? Try this 6-step guide
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Carin Booth, family and consumer science UGA extension agent in Hall County, developed a safe method for canning tomatoes. - photo by Kelsey Podo

Instead of giving your tomatoes away or tossing them out before they rot in your pantry, why not try canning them? 

Carin Booth, family and consumer science University of Georgia extension agent in Hall County, has developed a recipe for preserving tomatoes — one she is ready to share with the community.  

“Each agent has an area of expertise, and this is mine,” Booth said. “I teach food safety programming. A big part of my job, especially during the summer and into the fall, is food preservation.” 

Booth said she felt inspired to write the method after receiving many calls from people inquiring about how to property can tomatoes.  

To help you save your harvested tomatoes for the colder months ahead, The Times spoke with Booth and broke down her guide into six steps. 

Here’s what you’ll need: 

  • Tomatoes (any kind) 

  • Quart or pint glass Mason jars with lids/rings 

  • A stock pot large enough to hold a couple of jars 

  • Citric acid powder or a bottle of store-bought lemon juice 

  • One ladle 

  • One paring knife  

  • A pot large enough to hold at least a couple of quarts of water 

  • Drying rack or towel 

  • Bowl large enough to fill with ice water and dunk at least one tomato 

  • Slotted spoon/spatula, tongs or spider strainer 

Step 1: Finding the right tomatoes 

Although it may be tempting, Booth advises against canning tomatoes on the cusp of rotting. Instead, she recommends using ones that are either slightly underripe or just ripe.  

“You’re trying to make it shelf-stable,” she said. “Just think about it. You wouldn't want to preserve any vegetable or fruit when it’s about to go bad. You want it at peak freshness.” 

She said people can use any kind of tomato they like for preservation. The quantity canned is also up to people’s preference.  

Make sure to wash your tomatoes thoroughly with water before moving to the next step.  

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Make sure to heat your jars by placing them in a simmering pot of water. - photo by Kelsey Podo
Step 2: Heating the jars 

Grab a large stock pot that’s sizeable enough to hold the first batch of jars you want to use. Booth said you want to then fill the pot with water, making sure there’s enough to immerse the jars 1-2 inches under the liquid.  

Place your first batch of empty Mason jars into the pot without the tops/rings and bring the water to a simmer. It doesn’t matter if they turn on their sides or fill with liquid, you’ll take them out later. Do not heat the water beyond a simmer.  

Booth said warming the glass containers is a necessary step to ensure they don’t crack when you later introduce boiling water. 

As the jars heat up, turn your focus to the next step.  

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To separate the peels from the tomatoes, gently lower them into a pot of boiling water until the skin splits. - photo by Kelsey Podo
Step 3: Boiling, peeling and coring 

To ease the process of removing the peels, Booth recommends dunking the tomatoes in a separate pot of boiling water for around 30-60 seconds until the skins split. You can lower one tomato at a time with a slotted spoon, tongs, slotted spatula or spider strainer. 

Keep your separate pot’s water boiling to use in the fifth step. 

After the skin begins to split, take the tomato out and lower it into a bowl of ice water and bring it back out. Do this with all your tomatoes.  

Booth said this step cools them down for safer handling. 

Next, carefully peel away the skin. Taking a paring knife, carve out the center of your peeled tomatoes and discard the core.  

Depending on what you want to do with your canned tomatoes once they’re preserved, Booth said you can either cut them in halves or keep them whole. 

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Adding citric acid or lemon juice to your jars before packing the tomatoes helps deter harmful toxins. - photo by Kelsey Podo
Step 4: Adding acidity 

Booth said adding acid to the canning process is one of the most important steps to ensure no harmful toxins enter the mix. Because of the liquid and airless environment created when canning food, she said botulism, dangerous poisoning caused by bacteria, can take place. 

“The purpose of adding lemon juice (or citric acid) is to help acidify the tomatoes even more,” Booth said. “Botulism is what you want to prevent. Botulism comes from the botulinum toxin. It can make people sick, and it is a deadly toxin.” 

Unlike mold and yeast, Booth said botulism doesn’t reveal its presence with a foul smell or discoloration.  

“It’s hard to see if it’s in food or not,” she said. 

By incorporating acid, Booth said people can deter this toxin. 

One at a time, take a heated jar and sprinkle in either citric acid powder or store-bought bottled lemon juice.  

For a pint jar add 1 tablespoon of bottled lemon juice or ¼ teaspoon of citric acid powder. For a quart jar, add 2 tablespoons of bottled lemon juice or ½ teaspoon of citric acid powder. 

Now pack your tomatoes to the jars. 

Make sure to turn off the burner you used to heat the jars. 

Booth advises against using freshly squeezed lemon juice because its pH isn’t consistent like juice containers purchased at the store. 

“We know bottled lemon juice is 5% acidity,” she said. “Our recipes are tested. You don’t want to squeeze your own lemons in there.” 

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Leave at least a half-inch of headspace when you pour the boiling water into your jars. - photo by Kelsey Podo

Step 5: Boiling water 

Taking the water that has already been boiling in the separate pot (from Step 3), ladle enough into the jars so that you keep a half-inch of headspace. Turn off your burner. 

Put your lids on top of the jars, then screw on the rings to seal the containers.  

Place the jars upright in your large stock pot of water (the one that warmed the jars in Step 2), making sure the liquid covers their tops by at least 1-2 inches.  

Turn on your burner and bring the water to a boil.  

Once the water comes to a rolling boil, cover your pot with a lid. Booth said to then set a timer for 45 minutes if you’re using quart jars, or 40 minutes if you're using pint jars. Make sure to keep the water boiling for that length of time. 


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Place your canned tomatoes into a pot of water, making sure they're fully immersed. - photo by Kelsey Podo
Step 6: You’re almost there 

After the timer goes off, turn the heat off, remove the pot’s lid and allow the jars of tomatoes to rest until the water calms down (about 5-10 minutes).  

Remove the jar with either silicon potholders, jar lifters or something that will protect your hands from heat. 

Place the tomato jars upright onto either a towel or cooling rack, spacing them out by at least a half-inch.  

Booth recommends leaving them undisturbed for 12-24 hours. 

After this time, check to see if the metal tops have dipped down. If they have not, Booth said to repeat the boiling process from Step 5. If this doesn’t work, she recommends putting the defective jars in the fridge and eating them soon afterward.  

For the jars that did cooperate, you’re now done and have tomatoes you can store for up to a year.  

For more information about canning or preserving food, contact Booth at boothc@uga.edu or 770-535-8293. 

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