There was a time when canning tomatoes was as common as making eggs for breakfast. When we were a more agrarian society, no one thought of buying cans of tomatoes during winter months. Instead, they grabbed a jar or two from the cellar and rejoiced in the flavor of homegrown tomatoes that had been preserved at the peak of their ripeness. Nowadays, it may seem there is no reason to go to the trouble of canning–except that they taste so good and make January meals happy events bathed in the memory of last summer. You’ll also know exactly where the tomatoes came from, and, without a doubt, the tomatoes you grow yourself or find at a local farmers’ market will be far tastier than store-bought canned tomatoes.
Canning is a seasonal task, best accomplished when you have access to at least a half bushel of ripe summer tomatoes. For us, living in Connecticut, this is generally around Labor Day. Depending on where you live, it might be a little earlier or later. We have found that a half bushel yields about 8 quarts. While tomatoes themselves are acidic, pouring a little lemon juice into each jar ups the acid and ensures the safety of the tomatoes.
Although you don’t need a lot of special equipment, you will need at least 8 quart jars (I recommend having a few extra in case the tomatoes fill more than 8 jars or in the event one breaks) with new lids and rings. You also will need a large pot, such as a canning pot or deep stockpot with about a 21-quart capacity. A jar lifter is handy, but both my coauthor, Mary, and I have been known to get by with good tongs and thick pot holders. If you have a canner jar rack that fits in the pot, so much the better.
Set aside a few hours to can the tomatoes, and expect a damp, humid kitchen.
Makes 8 quart jars
1/2 bushel tomatoes
1 cup fresh lemon juice (4-5 lemons)
8-12 fresh basil leaves (optional)
Fill a large, deep pot about halfway with water. Cover and set it on a back burner over high heat to come to a boil. When it boils, turn off the heat, but leave the lid on to keep the water as hot as possible.
Fill a large saucepan about halfway with water. Bring to a simmer over medium-high heat. Fill a large bowl or the sink with cold water.
Immerse 2 or 3 tomatoes in the simmering water for 50 to 60 seconds. Lift them from the water with a slotted spoon and plunge into the cold water. When cool, slip off and discard the skins. Transfer the peeled tomatoes to a bowl. Repeat until all the tomatoes are peeled. You will have to change the water several times to keep it cold. You may also want to replenish the saucepan of simmering water.
With a sharp paring knife, remove and discard the core from the tomatoes and cut each into halves or quarters, depending on their size.
Put the tomatoes into a sterilized quart canning jar (see “How to Sterilize the Jars and Lids” below). Push as many tomato pieces as you can into the jar to fill it to within 1/4″ of the rim. Work around the edges of the jar with the handle of a long-handled, clean wooden spoon to expel any air bubbles. After you do this, you may be able to fit another quarter or half tomato into the jar.
Add 2 tablespoons of the lemon juice to the jar. You can also add a leaf or two of basil, if desired. Wipe the rim of each jar with a clean, dry kitchen towel to free it of stray seeds or liquid. Set a sterilized lid on the jar. Secure it with a screw-on ring. Repeat until you have filled as many jars as you can with tomatoes.
Let the water in the large pot return to a boil over high heat. Submerge the jars in the water using a jar lifter or sturdy tongs. If the water does not cover the jars, add more hot water (from a boiling kettle is best) until they are completely covered with water.
Let the jars boil in the water for 45 to 50 minutes. Remove the jars from the water bath with the jar lifter or tongs, and set them on a dry kitchen towel to cool. Leave ample room for air to circulate between the jars, and do not let them touch each other as they cool.
Leave the jars undisturbed until completely cool, usually 8 hours or overnight. When they are cool, check that the lids are concave. Do this by pushing on the lids with your finger. There should be no movement or give. (If any are not concave, remove the lid and transfer the tomatoes to a refrigerator container, and use as soon as you can.) Remove the rings, which can be used again, and store the lidded jars in a cool, dry place. They will keep for 1 year, at least.
SAFETY ISSUES WHEN CANNING TOMATOES
Canning acidic ingredients such as tomatoes is easy and safe. It requires only sterilized canning jars and a deep pot of water (no pressure cooking involved). It’s easy to tell right from the beginning if the process worked: Once the jars cool, the lids will be obviously concave. In fact, during cooling you might hear a slight “sucking” sound. That’s the sound of the vacuum inside the jar fixing the lid so that the seal is as tight as can be. Another way to tell if the vacuum has formed is to tap the lids with a spoon before the jars cool and then tap them afterward. The sound of a properly sealed lid will be deep and resonant, while the sound of a lid that has not yet formed the vacuum is tinny.
When you open the jar, it will release with a reassuring pop, which indicates the tomatoes are as fresh as when you pushed them into the jar. It might reassure you to know that if the seal breaks and the tomatoes spoil, you will know it as soon as you remove the lid: The tomatoes will foam and sputter in ways that are not normal.
HOW TO STERILIZE THE JARS AND LIDS
Some dishwashers have a “sterilize” cycle, which is a good way to make sure your jars are as clean as can be. Otherwise, start with clean jars that you have washed in hot, soapy water and then rinsed well. Submerge them in the canning pot filled with boiling water. Let the water boil around them for about 5 minutes, and leave them in the hot water with the heat switched off until you are ready to fill them. Clearly, this should not be done too long before canning.
Canning lids are flat with a rubber ring around the inside. Sterilize them, too, in a pan of boiling water. Lift them out with tongs or a lid-lifting tool (which is magnetized to grip the lids). You can reuse the screw on rings from year to year, but the screw on lids are good for only onetime use. The lids will rust if you leave them on the jars during storage.
From Sustainably Delicious. Photo by Andre Baranowski.