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ingredients and techniques

Tomato Frenzy: Canning

john's picture

Since mid-July, the test kitchen has been inundated with tomatoes. Eastern Tennessee had record-breaking temperatures and hardly any rainfall in June, followed by a few weeks of daily afternoon showers. As a result, many of us had to pick half-ripe tomatoes before the crazy weather caused them to crack and split on the vine. The first onslaught—a whole bushel (about twenty pounds) of very ripe tomatoes—arrived last week without warning, causing a scramble for mason jars and fresh lids. As we continue to harvest our ten San Marzano plants, three Cherokee Purples, and a half-dozen Dr. Carolines, we have also been the beneficiaries of several tomato “gifts” from friends and growers at the farmer’s market. As this glut lasts, we will continue to post weekly on different ways of using and putting up tomatoes. First up: classic canned “whole” tomatoes. Why quotation marks? As you can see from the photos, this first batch started out whole, but they were so ripe that the peeling and canning process made them appear—for lack of a better descriptor—“lightly crushed.” Either way, they will be delicious in sauces, stews, chilis, soups, and braises all winter long. All it takes is some know-how, half a day of your time, and a few small investments.

Despite the recent canning and preserving “revival” (for many, canning is and always has been a way of life), lots of people still get a little skittish after years of hearing second-hand tales about botulism and thinking that a pressure canner is dangerous. This is why tomatoes are great to start with: being acidic, tomatoes are inhospitable to most microorganisms and only need a hot-water bath canning process. What’s more, tomatoes are probably the most useful canned staple to have on hand. Add all of these to the fact that fresh supermarket tomatoes are generally bland during the harvest season (let’s not even talk about winter… ugh), and you have a healthy stack of reasons/excuses to source some tomatoes and get canning. Truly a gateway canning project.

First step: assemble a very large stockpot, a canning rack that fits nicely in the bottom, a roasting pan, a fresh box or two of quart-size mason jars (twenty pounds of tomatoes—one bushel--required eighteen quart jars for us), a jar lifter, a canning funnel, citric acid or bottled lemon juice, and a ladle. Second step: go to a farmer’s market and ask someone with tomatoes for sale if they have flats of tomatoes for canning. Many farmers will give you a special rate for canning tomatoes, as they do not need to look pretty and will probably be picked over by other customers. Another good approach is to ask farmers for deals toward the end of a market, as they will probably not want to take anything home. Whatever you do, do not go into a specialty food store or coop and pick the most beautiful heirlooms you can find. You will be throwing money away with no discernible pay-off in the final product. In fact, though the tomatoes pictured are Better Boys, the best to use are the smaller, meaty varieties, such as San Marzanos and Romas (FYI: you cannot can cherry or grape tomatoes… luckily, they're your best bet for flavorful, fresh supermarket tomatoes in the winter).

Now that you have all the materials, it’s time to clean and sterilize the jars and lids. After washing them by hand or in a dishwasher, fill a stockpot with water (leave some space for the volume of the jars), place the canning rack on the bottom, bring to a boil, and add as many jars as will fit using the jar lifter tool. Boil for ten minutes, carefully remove and pour the water out of each jar, and add another batch. Meanwhile, put the lids and rings in a bowl and pour boiling water over them to cover. Let them sit for ten minutes as well.

Set aside the jars and lids to dry. Using a sharp knife, make a shallow X-incision in the skin of each tomato opposite the stem. Place them in a single layer in a roasting pan and cover with the boiling water from the stockpot. Wait until cool, slip the skins off, and cut out the stems and any blemishes or green areas that are on the tomatoes. Place the peeled and cored tomatoes in a pot over medium heat and bring to a simmer for five minutes.

Using the canning funnel, ladle the tomatoes into the jars, leaving ½ inch of headspace at the top. When all of them are filled, it’s time to add a little extra acid for luck. Tomatoes have unpredictable acid levels; this is true even of old-fashioned varieties with a high-acid reputation. To be safe, add 1⁄2 teaspoon citric acid or 2 tablespoons bottled lemon juice to each quart jar. Do not add vegetables or other ingredients that would lower the acidity of the canned product. A single small washed fresh herb leaf, like sweet basil, is acceptable; its flavor will intensify with time.

Before placing the lids on, make sure the rim of each jar is clean and dry. Place the lids on and screw on the rings. Be sure not to tighten them too much; remember: as air expands during processing, some of it needs to escape. Refill the stockpot with water and bring back to a boil. Carefully add the jars using the lifter tool. As you add them, if you notice the water getting close to the top, pour or bail some out using a heat-proof glass measuring cup. The jars should be covered by approximately 2 inches of water. When the water returns to a boil, start your timer. Boil the quart jars for 45 minutes if you are at or near sea level. Be sure to add the appropriate amount of time for your altitude:

1,001-3,000 feet, add 5 minutes
3,001-6,000 feet, add 10 minutes
6,001-8,000 feet, add 15 minutes
8,001-10,000 feet, add 20 minutes

Voilá! Winter-time tomatoes with summer-time flavor. Let the jars cool undisturbed on the counter for 12 to 24 hours. During this time you will hear the lids “pop” as the air shrinks and sucks them down. This might take some time. If, after a day, the lids do not seal properly, try processing again (I’ve never had this problem occur so don’t worry too much about it). When everything is nice and sealed up, we like removing the rings. Why? If a seal fails it will be very obvious.

Phew! Don’t let the length of this blog deter you from trying your hand at canning. It’s not any more complicated than your average mac and cheese recipe, but you have to do things right, and that means lengthy explanations and more exact instructions. I promise you, the effort is worth the reward. Let us know how you fare, or if you have any tips we can use as we weather this deluge of beautiful tomatoes. For more information on canning tomatoes (and just about anything else you can think of), check out the Canning chapter in the 2006 Joy of Cooking


Edith Anderson's picture

These jars take me back to my mom's hot kitchen full of fans and bushel baskets. At the end of a long tiring day, there were jars on every flat surface, lined up like soldiers on white towels, cooling and catching the light like these. High pitched pops and boinks let you know one more jar of food was sealed and ready for winter cooking.

Dorothy Stohl's picture

Actually, you can can grape tomatoes. There is a recipe for pickled grape tomatoes in the Ball Blue Book. And Ball also has a recipe for "cold pack" tomatoes in which you don't have to cook the tomatoes before putting in the jars. Just an FYI to save time and work.

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