Jars of preserved tomatoes are among the most versatile and popular pantry staples to make at home. I cook 100-pound batches of tomatoes at a time, filling up several shelves with quarts of tomatoes, and yet I still burn through our inventory well before tomato season arrives again.
Since we put up so many jars, I have streamlined the process. Instead of blanching, peeling, and seeding tomatoes, I pass cooked tomatoes through a food mill, which succeeds in getting rid of much of the skin and some of the seeds. I also keep the sauce on the thin side. This not only cuts down on having a pot of tomatoes taking up space on the stove for hours, it also yields a fresher tomato flavor. If I decide to reduce the tomatoes into a sauce, I can do so later. But if I just want a spoonful of fresh-tasting tomato juice for gazpacho, all I have to do is pop open a jar.
Selecting the right tomato is crucial. I buy locally grown San Marzano tomatoes—the ultimate canning variety (just ask the Neapolitans). These meaty, firm tomatoes offer more pulp than the round, juicy heirlooms. Timing is also important. The best time to can tomatoes is peak season (typically August and September), when they are not only inexpensive but also ripe. The decision whether to add either citric acid or lemon juice to tomatoes before canning them stokes debates among passionate canners. Although tomatoes taste acidic, their natural pH level can veer upward of 4.6, the border of safety when determining whether a product is acidic enough to water-bath process. To play it safe, food scientists recommend adding citric acid or lemon juice to tomatoes. But many old-school canners who have made tomato sauce for years without adding any acid feel this recommendation is overkill.
While I tend toward the cautious side, I prefer not to add ingredients that do nothing to enhance the natural flavor of the product, so I don’t acidify my tomatoes. Instead, I test a jar from each batch with a pH meter. In general, I have found that late-summer tomatoes yield an average pH of 3.5. While it is a good exercise to check the pH of canned items, it is absolutely necessary with this recipe. If you don’t have a pH meter to test your tomatoes, play by the book and add 1 tablespoon lemon juice or 1/4 teaspoon of citric acid to each pint, double for each quart. Or you can pressure-can the tomatoes. Pressure canning brings the internal temperature of the jar high enough to kill spoilers even if acidity levels aren’t below 4.6 pH. Another alternative is to divide the sauce among resealable plastic bags and freeze them. If you make a much larger batch than the one I’ve provided here, factor in an extended simmering time for the tomatoes.
makes 4 to 5 pints
Ingredient: Tomatoes, preferably San Marzano or Roma. About 12 cups or 6 pounds or 2700 grams or 99.5%
Ingredient: Kosher salt. 2 teaspoons or 1/4 ounce or 10 grams or .5%
1. Core and quarter the tomatoes. Put the tomatoes and their juices into a large pot. Bring to a boil, decrease to a gentle simmer, cover, and cook, stirring every 5 minutes to prevent the bottom from scorching, for about 20 minutes. Uncover the tomatoes and cook until the tomatoes have released all of their juices and become very soft but before the juices have thickened substantially, 15 to 20 minutes more. Pass through a food mill fitted with a coarse disk and season with salt to your liking (about 2 teaspoons).
2. Scald 5 pint jars in a large pot of simmering water fitted with a rack—you will use this pot to process the jars. Right before filling, put the jars on the counter. Meanwhile, soak the lids in a pan of hot water to soften the rubber seal.
3. Using a ladle, divide the tomato sauce among the jars, leaving a 1/2-inch space from the rim of the jar. Check the jars for air pockets, adding more tomatoes if necessary to fill in any gaps. Wipe the rims with a clean towel, seal with the lids, then screw on the bands until snug but not tight.
4. Place the jars in the pot with the rack and add enough water to cover the jars by about 1 inch. Bring the water to a boil and process the jars for 15 minutes (start the timer when the water reaches a boil). Turn off the heat and leave the jars in the water for a few minutes. Remove the jars from the water and let cool completely.
Excerpted from The Preservation Kitchen by Paul Virant and Kate Leahy. Copyright © 2012 by Paul Virant and Kate Leahy. Excerpted by permission of Ten Speed Press, a division of Random House. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission from the publisher.