How to preserve summer tomatoes so you can enjoy them all year long

When I planted Mortgage Lifter, Mr. Stripey, German Red Strawberry, Early Girl and Roma seedlings in my backyard, I had dreams of filling baskets with sun-ripened tomatoes. I imagined jars of canned tomatoes cooling on the kitchen counter as well as a winter filled with a sense of self-sufficiency and just a little bit of gloating.

Instead, the squirrels and I have had our battles. There will be no moments of happy homesteading. I harvest one or two tomatoes a day and the little monsters snack on the rest. If squirrels, bunnies or groundhogs have invaded your garden, take heart: It's been a banner year for small farmers. Summer tomatoes are abundant, delicious and at a good price.

It is a great time to start a tomato canning tradition.

Tomatoes are the most useful ingredient in my pantry, particularly through the winter when many cold-weather recipes call for a can of them. In my dinner rotation, sauces, stews, soups, enchiladas, pizzas and parms all use them. It's such a relief to give up lugging home heavy cans from the grocery store and, instead, reach into the pantry for my own home-preserved version.

If you're new to canning, here's some advice:

• Select tomatoes that are ripe or slightly underripe, cutting out any black spots or bruises. Slicing tomatoes such as Brandywine, Beefsteak and Big Red are the most commonly preserved, while Roma tomatoes are another excellent choice - all are meaty varieties with thick walls and small seed sacks. Heirloom tomatoes are fine, but often have a higher water content and may result in a watery flavor once canned. Red tomatoes are prettiest in the jar, but a mixed bunch of every shape, color and size also works well, with the exception of grape or cherry tomatoes, which are too hard to peel.

• Clear the counters and make room. This is a big, messy job that starts with placing the largest pots, pans and bowls into an assembly line and ends with cleaning the kitchen.

• Remove seeds and skins. They may turn bitter in the jar. Remove the skin by blanching: Slice an X through the base and dunk in boiling water, and the peel will lift off in satisfying swaths. Plunge your fingers into the cells, scooping and discarding the seeds and gel. Then tear the remaining tomato flesh into large pieces.

• Crush the tomato pulp. Crushed canned tomatoes can separate into liquids and solids in the jar. This does not affect the tomatoes' usefulness, but it isn't as pretty. I crush, smash, tear and combine the pulpy and watery tomato meat until it's a cohesive, chunky mixture, then begin cooking those crushed tomatoes - about a quart at time - as I continue peeling, seeding and tearing the rest. Essentially, I'm a one-person band concurrently banging the cymbal, playing the harmonica and fiddling. This is the big work of tomato canning and shouldn't be rushed.

• Adjust acidity. Safe water bath canning relies on preserving foods with dependably high acidity, measured as pH. Because tomatoes have a wide-ranging pH, bottled lemon juice or citric acid is used to adjust the mixture to a safe level. Citric acid is a shelf-stable synthetic version of the naturally occurring compound found in citrus.

Salt is not needed for preservation, but may be added for flavor. Use only kosher or fine sea salt, not iodized, which can add a metallic aftertaste.

• Use what you have. The greatest yield will come from blanched, peeled and seeded, hand-crushed tomatoes. Canning does not require special equipment. It is possible to preserve pint jars in a large stockpot, fashion a rack for the bottom of the canner from a cake rack and to use a cooler for an ice bath. Two tools I highly recommend: a jar funnel and a rubber-coated jar lifter. I've used a measuring cup to add ingredients to jars, and I've McGyver'd a tool to help lift hot jars from the boiling water by twisting rubber bands around the ends of kitchen tongs, but the two low-cost tools are safer to use.

Veteran canners rely on special kitchen tools to make the preserving process easier. For example, a food mill processes quartered, cooked-until-tender tomatoes, removing seeds and skins for a smooth sauce. The near-legendary, budget-busting Squeezo is a grinder that removes peels and seeds and melds the textures for ideal crushed tomato consistency.

Tomato preservation is a task best shared with family or friends, but if working on your own, you will still end the day in a kind of exhausted glory and with a pantry full of summer's bounty.

• Troubleshooting: Never add anything except lemon juice or citric acid and salt to the jar. Adding meat, garlic, mushrooms, peppers, onions, herbs or spices will alter the pH and will render the contents dangerous for consumption.

After processing, if the tomato water and pulp separate in the jar, the liquid rising to the top, the tomatoes were not crushed enough or were added to the pot too quickly. It does not affect the taste or the shelf-stability at all. Shake the jar before using.

Any tiny amount of food left on the rim of the jar before placing the lid can interfere with the seal. Clean the jars meticulously before covering.

Do not move the jars from the water-bath canner too quickly. Allow them to rest in the canner for 10 minutes to slow the boiling inside the jar. Vigorous boiling can trigger siphoning; the contents may bubble up and lift the lid, breaking the seal.

After processing, any jars with failed seals should be refrigerated and used within 2 weeks.

Water Bath Canning Step-by-Step

For shelf stability, the USDA recommends water bath canning to process and seal jars of low-pH (high acid) foods like jams and pickles (as well as some tomato products). The filled jar is closed with a gasket-edged lid and placed in the canner. A threaded ring holds the lid in place during the processing. (While the lids cannot be reused, the rings can be.)

While in the water bath, the jars boil for the time indicated in the recipe and the food inside the jar heats to the same temperature as the boiling water (220 degrees) equalizing the pressure in the jar. When the jar is pulled from the water bath, the gasket on the lid seals, making a pinging sound. When sealed, the dimple on the top of the lid will be convex. Some jars ping while still in the water bath. Some ping an hour later. Be patient.

Any lidded pot can be used as a canner as long as the jars (atop a rack) can be submerged in the boiling water. The rack can be a cake rack or even a circle of canning rings tied together. Anything that will ensure the jars will not be knocking against the bottom of the pot when the water is vigorously boiling will work. Even a folded towel is a suitable cushion, but annoyingly spectre-like as it pillows up in the boiling water. It's helpful to have a kettle of boiling water at the ready to make adjustments to the water height once the jars are in place.

Set up a baking sheet lined with a towel to hold the jars both before and after processing. The hot jars should not come in contact with a cold surface or they could crack; the towel provides a cushion.

High-pH (low acidity) foods such as non-pickled vegetables, any proteins, dried beans and stock must be pressure canned, an entirely different process. When preserving and processing, use recipes from known sources and follow the directions precisely with regard to jar size and time to process. Adding extra ingredients, especially proteins, mushrooms, peppers, garlic and onions, can change the pH of a recipe and increase the likelihood of botulism or molds.

Troubleshooting:

Seals will fail when there is food residue between the flat lid and the jar; clean the jar rims and threads thoroughly. Seals will fail if the jar is not held upright going in and coming out of the water bath and if the processed jars are moved before they are entirely cool. Seals will fail if the jar is filled with cold food, so process as soon as possible after cooking.

Place a rack on the bottom of the canner and fill with water so that it will cover the jars by 1 inch. If you have hard water, add 2 tablespoons white vinegar for sparkling jars. Set the canner over high heat, cover and bring to a boil. Reduce the heat so the water is at a simmer until it is time to can.

Line a rimmed baking sheet with a folded tea towel. In hot, soapy water, wash the number of jars needed (indicated in every canning recipe) plus one extra, just in case. Invert the clean jars on the towel and let them dry. Have at hand the lids and rings, a ramekin or small bowl for any extra, a teaspoon to adjust the head space, a few folded paper towels, a ladle and a chopstick.

Steps:

Make the recipe as instructed.

Place a jar funnel inside one jar. Ladle the hot food into the jar to the recommended head space. Repeat with the remaining jars. Use the teaspoon to adjust the head space, as needed. Run the chopstick around each jar's contents to remove any air bubbles.

Dampen a paper towel and carefully clean the inner and outer jar edge and threads of the jar. Once the jar is wiped clean, place the flat lid, gasket side down, on top. Add the outer ring and finger tighten.

Increase the heat under the canner to return the water to a boil. Using a jar lifter, transfer the upright jars into the canner and atop the rack or towel. When all the jars are in place, cover the pot and wait for the water to return to a vigorous boil. Start the processing timer only when the water is boiling again.

Remove the jars one at a time, returning them to the towel-lined baking sheet. Keep the jars upright (resist the urge to pour off any water pooled on the top of the jar.) Listen for the ping that indicates the jar has sealed and look for the dimple on the top of the lid to be convex. Let them cool in place for several hours.

When cooled, remove the ring on each jar and lift it by the flat lid. If the lid releases, the seal is unsuccessful. Jars that do not seal should be refrigerated and consumed within 1 month. If all the jars in a batch fail to seal, review your process. If the seal failure is clear immediately, empty the contents of the jars into a pan, reheat to an active boil, and reprocess. The flavor and texture of the foods may suffer from being heated and processed twice.

Wash and dry the jars, be sure to label with both the contents and date, and place in a dark, cool space to store.

The contents of most water bath-processed jars will stay delicious for up to 18 months.

Canned Crushed Tomatoes

Putting up tomatoes, canning them in jars for shelf-stability, is a summer task that can pay off all winter. Whether the tomatoes come from your backyard garden or the local farmers market, the flavor will be fresh and bright in the winter and the sense of satisfaction will be enormous.

Start with 25 pounds - a box - to make the most of the time and mess that will come.

Select tomatoes that are ripe or slightly underripe. Any tomato can be canned, but meaty types such as Brandywine, Beefsteak and Big Red, as well as Roma varieties are a better choice. Avoid grape or cherry tomatoes, as they are challenging to peel.

Do not use overripe tomatoes or those with bruises or black spots.

Adjusting tomatoes' pH is critical for safe preserving and is accomplished by adding the USDA and National Center for Home Food Preservation standard quantity of bottled lemon juice or citric acid, which is a more economical option and is available at grocery and hardware stores. Add nothing else to the jars, or risk altering the pH and making the product unsafe.

Process in pint or quart jars, or a combination of the two, selecting a size that makes the most sense for you. Pints easily fit in most 8-quart stockpots, but a canner is necessary for processing quarts. One quart (32 ounces) of crushed tomatoes will stand in for a 28-ounce grocery store can in any recipe.

A note on yields: The yield on canning can vary, depending on the variety of tomato, cooking time and other factors.

Equipment: One 8-quart stainless steel or other nonreactive pot, a canner or another very large pot in which the jars can sit upright on a rack and still be submerged, a jar-lifter, a cooler (at least 15-quart capacity) filled with ice water, 2 large bowls, a canning funnel, 7 to 8 quart or 14 to 16 pint canning jars, as well as corresponding rings and lids.

Storage Notes: The jars can be stored in a cool, dark place for up to 18 months.

Where to Buy: Canning supplies are available at hardware stores, groceries and online.

25 pounds ripe but firm tomatoes (about 30 to 45, depending on size, see headnote)

About 4 teaspoons (28 grams) citric acid or 1 cup (240 milliliters) bottled lemon juice

Kosher or fine sea salt (optional)

Set up for water-bath canning. Fill the largest bowl in your kitchen or a 15-quart capacity cooler with ice water.

Set up 2 large bowls: One for the tomato cores, peels and seeds and the other for the crushed tomatoes.

Bring a large pot of water to a boil over high heat and reduce the heat so the water is at a steady simmer. Slice an X just through the skin at the bottom of each tomato. Gently slide a few tomatoes at a time into the boiling water for 30 to 60 seconds (depending on the size and ripeness of the tomato).

Continue with the remaining tomatoes, letting the water return to a steady simmer between batches and blanching a few tomatoes at a time. The tomatoes will float to the surface at about the same time the peel has loosened. As they bob up, use a slotted spoon to transfer them to the ice bath to stop the cooking.

Working over one large bowl, core and remove the peel from the tomatoes. Cut out any bruises or black spots. Halve the tomatoes and, using your fingers, scoop out and discard the seeds and gel. Crush and tear the tomato flesh into the other large bowl.

Begin multi-tasking. When about a quart of torn tomato pieces are in the large bowl, use both hands to smash and squeeze them. As the tomatoes break down, they will separate into a watery soup with larger pieces of pulp. The more the tomatoes are massaged and the solid and watery textures combined at this step, the less likely the contents of the jars will separate into tomatoes and liquid after processing.

It is easier to reach the correct consistency by working in smaller batches. When you have about 4 cups of crushed tomatoes in the bowl, add them to an 8-quart or larger nonreactive pot and bring to a boil, breaking down the tomatoes further with a potato masher or strong wooden spoon. Reduce to a strong simmer and continue to hand-crush tomatoes in the large bowl and add them, 4 cups at a time, to the tomatoes in the pot, returning the mixture to a boil between additions. (Keep count of the 4-cup additions and prepare the number of jars needed: 4 cups is equivalent to 1 quart or 2 pints.) When all the tomatoes have been added to the pot, bring the entire batch to a rolling boil for 5 minutes, stirring continually.

Ladle the hot crushed tomatoes into the prepared jars, leaving a 1-inch head space (that is, an inch between the rim/underside of the lid and the food or liquid in the jar). Add ½ teaspoon citric acid or 2 tablespoons lemon juice to each quart jar. (Add ¼ teaspoon citric acid or 1 tablespoon lemon juice to each pint jar.) If using salt, add 1 teaspoon per quart jar or ½ teaspoon to each pint jar. Using a chopstick or a similar tool, stir the contents of each jar, releasing any air bubbles. Before sealing the jar, double-check that a ½-inch of head space remains, adding a bit more tomato if needed.

Carefully clean the rims and threads of each jar with a damp paper towel. Check the rim with your fingertip dipped in white vinegar: It should be squeaky-clean. Place the lids and rings on the jars and finger-tighten the rings.

Process in a boiling water bath for 45 minutes if using quart jars, 35 minutes if using pint jars. If processing both sizes of jars, boil for the full 45 minutes.

Let the jars rest in the canner for 10 minutes to help prevent siphoning (when the boiling ingredients bubble up under the lid, breaking the seal). Using a jar-lifter, lift the jars from the canner, keeping them upright, and place on a towel-lined baking sheet. (Do not use kitchen tongs to lift the jars.) Do not move the jars for several hours.

When thoroughly cool, remove the rings and test the seal by lifting the jar by the flat lid. If it has not sealed, and only within 24 hours of the original processing, reheat the tomatoes and reprocess as before, including adding more citric acid or lemon juice. If the seal fails after 24 hours, or in the days and months following, discard the tomatoes.

Wash and dry the sealed jars, label and date them and store in a dark, cool place for up to 18 months.

Altitude Adjusting: Because water boils at lower temperatures at higher altitudes, processing times should be increased to reach a safe temperature. From 1,000 to 2,999 feet above sea level, add 5 minutes. At 3,000 to 5,999 feet above sea level, add 10 minutes. At 6,000 to 7,999 feet above sea level, add 15 minutes. At 8,000 to 10,000 feet above sea level, add 20 minutes.

Makes 28 to 32 servings (7 to 8 quart jars or 15 to 16 pint jars)

Nutrition (based on ½ cup) | Calories: 32; Total Fat: 1 g; Saturated Fat: 0 g; Cholesterol: 0 mg; Sodium: 9 mg; Carbohydrates: 7 g; Dietary Fiber: 2 g; Sugars: 5 g; Protein: 2 g.

From food writer Cathy Barrow.