One of the joys of growing your own tomatoes is making your own tomato puree and preserving it for the winter months.

Growing up my family has always canned their own food but never their own tomatoes. Since last year, my husband and I have made it a personal project to grow and preserve our own tomatoes. It has been quite the endeavor teaching my husband the ins and outs of water canning but very rewarding nonetheless. There’s no better bonding experience than spending hours canning with your loved ones and then enjoying a tasty pasta dinner while using your canned bounty. It’s one of the most fulfilling feelings that one can experience. Even if you don’t grow the actual tomato, like crazy me, it’s still very wonderful to enjoy your own canned tomatoes for any tomato based recipe in the dead of winter.

Canned Tomato Puree

Puree

25 lbs. tomatoes

Kosher salt

Citric acid

Equipment

7 wide mouth quart mason jars with lids and rings

Large stock pot with lid

Immersion blender

Clean kitchen towels

Water Canner

Jar grabber or tongs 

Lid Magnet

Jar funnel

Ladle

Sterilizing the jars, rings and lids:

Place your mason jars into your water canner and cover them with water, making sure you fill the inside of the jar so they don’t float and are fully submerged. Place the lid on your canner and set on the stove on high heat. Once your water is at a full boil, set a timer for 15 minutes. After the time is up, turn off the heat and carefully remove your jars from the hot water. Pick up the jars with your jar grabber or a pair of tongs and carefully dump out the water, place your sterilized jars onto a clean kitchen towel to dry.  

Leave the water in the canner, you can use it later to can the tomato puree. Just put the lid on the canner and leave on low heat to keep the water warm. That way it won’t take as long to get it boiling again.

In a small pot, place your rings and lids. Fill the pot with water so everything is completely submerged. Set on high heat and boil. Once boiling, leave for 5 minutes and then turn off the heat. Leave the rings and lids in the hot water until you are ready to use them. The warm water will keep the rubber gasket on the lids lubricated so it has a chance to create a better seal on the jar. 

Prepping the tomatoes:

Sort through your tomatoes to check for any mold or bruises, it’s important for your tomatoes to be fairly blemish free and definitely free from mold. If you have some severely bruised tomatoes you can put them aside to make a fresh tomato sauce without canning.

After you’re done sorting, wash the tomatoes thoroughly with cool running water to rinse off any dirt that may have settled on the skin. With a sharp paring knife, cut the tops off of the tomatoes and cut your tomatoes into quarters so they are manageable pieces. Place your tomato pieces in your large stock pot. 

Once you’ve washed and cut up all your tomatoes, place your stock pot on medium heat and put the lid on. Let your tomatoes steam for about 10 minutes before checking and stirring your tomatoes, it is important to occasionally stir the tomatoes to ensure nothing is burning to the bottom of the pot. 

Cook the tomatoes with the lid on until they release most of their juices and the fruit has softened considerably, you want them to pretty fall apart. When the tomatoes get to this stage remove the lid and blend the tomatoes with an immersion blender. Blend the tomatoes until they are completely smooth. Continue cooking the blended tomatoes until the liquid has reduced by half and the puree has thickened, you want it to be a saucy consistency with a little bit of water. 

Packing the jars:

Once your tomatoes are cooked, blended and thickened it’s time to pack the puree in your sterilized jars. Take your sterilized jar and your tomato puree, using your jar funnel ladle the puree into the jar until it reaches about ½ from the top. This is called headspace and it’s to leave room for the puree to bubble in the jar. If you don’t leave enough space, you might get juice leaking from the jar and you won’t get a tight seal on the lid. 

When all your jars are filled with the tomato puree, portion 1 teaspoon of kosher salt and a half teaspoon of citric acid into each jar. The salt and citric acid ensure that the PH in the tomato puree is balanced inorder to make sure it’s shelf stable.   

Take a wet kitchen towel and wipe the lip of each jar to clean off any puree that may have gotten on the jar. Use a lid magnet to place the lids on each jar taking care not to touch the inside of the lid. If you touch the inside of the lid it will no longer be sterile for the jar. Fasten each lid with a ring, making sure not to over tighten. You just need it tight enough to keep the lid in place and secure until the jar gets sealed. Now that the jars are ready, let’s get them sealed!

Sealing the jars:

Remember the water canner we left on low? Well, it’s time to use it. 

Check the height of the water in the canner, if it’s still over half or half full empty some of the water out with a small pot. You want to make sure the water level isn’t too high for when you put the jars in the water bath. 

Fasten the rack that comes with the water canner to the sides of the pot and carefully load your jars onto it. I load in two jars at a time and I make sure the jars are facing each other on opposing sides of the rack. That way the rack doesn’t get too heavy to one side and there’s a counter balance of weight. If you don’t make sure that the rack is balanced the rack could fall off the pot and splash into the water canner. Believe me, you don’t want that to happen, it's such a mess. If you properly balance the rack, all the jars should fit perfectly on the rack and the last jar should go in the middle. 

Once the rack is loaded you can lower the entire rack into the water bath. Make sure the water covers the tops of the jars by at least an inch or two of water. Set the stove to high heat, put the lid back on the canner and wait for the water to boil. When the water is at a rolling and vigorous boil, set a timer for 40 minutes. While waiting for your jars to be done you can set up a station for the jars to cool. I usually set up a spot on my counter or bring an extra folding table into my kitchen. I then put down a layer of clean kitchen towels down so the hot jars don’t scorch my table or countertop. 

After 40 minutes have passed your tomato puree has been processed. Turn off the heat and carefully lift the jars out of the water bath using a jar grabber. Tip off any excess water that has accumulated on top of the jar, be careful to not touch the lid. It will be slightly puffed out and that’s ok, it’s just the hot air in the jar that helps create the seal. 

Leave your jars to cool at your designated cooling station that you previously set up. As the jars cool you will hear popping sounds and that’s the glorious sound of the jar lid sealing shut.

Cool your jars completely before dating and storing them in a cool dark place such as a cellar or even a pantry cabinet. A sealed jar of tomato puree will keep for 12-18 months if processed correctly. Enjoy your homemade tomato puree!

*Notes: 

The best tomatoes to use for this canning recipe are Roma tomatoes or a saucing heirloom tomato. This year I grew Cesare’s Canestrino di Lucca Tomatoes and Blush Tomatoes for my tomato sauces and canning recipes. They are honestly by far the best saucing tomatoes I’ve ever used. The real surprise were the Blush Tomatoes for sauce because they are technically a snacking tomato but they make such a stellar sauce. The Cesare Canestrino Tomatoes are the real saucing tomatoes and they are somehow even better. So if you can get your hands on these gorgeous tomatoes great! But if you can’t feel free to use whatever saucing tomato you prefer, it’s all about availability.