Our world sometimes feels much larger than it once did, and at a time when we can buy produce from half a world away whenever we want it, some traditional methods of food preservation, like canning, may seem like old news. But for many of us, there is a sort of romance in the process: picking the perfect produce, choosing a recipe, and then organizing the jewel-toned jars on your pantry shelf, admiring your hard work.
Canning is a bit of a complicated process, and there’s value in doing plenty of research before you embark on the adventure. You’ll need lots of tools and equipment, plus the patience to work cleanly, safely, and sometimes a little bit slowly. It may not be as fun as opening a jar of jam 5 months later, but it’s certainly a rewarding part of the process. In addition to the very basics we’ll discuss here, there are thousands of resources for special tools, great recipes, and tips and tricks for successful canning, and we always encourage future-canners to review the USDA’s safety guidelines before beginning.
The process of canning heats the food you are preserving to high enough temperatures (215°F) to destroy bacteria, and also heats the jars to form a proper seal. Once they cool, you can store your foods at room temperature for an extended period, sometimes more than a year.
The right equipment makes canning much easier. While you can certainly preserve food without some of this equipment, the proper tools truly streamline the process.
Glass canning jars come in multiple shapes and sizes. They are made to hold up to the high heat of hot foods and lengthy processing times. Always use jars that are specifically meant for canning, as many glass containers will not form a proper seal and may not be able to withstand high heat. Ingredients for canning should be packed tightly in the jar, so choose a size to suit the ingredient.
Jars are sold with matching lids and bands for sealing. The bottom of the lid has a sealing compound that activates when heated during processing. The bands screw on to hold the lids in place. Due to the nature of the sealing compound, lids can only be used once; they will not form a seal a second time. Once the jar is unsealed and opened, you can use the lid for refrigerator storage, but it is helpful to mark it so you know not to use it for canning in the future.
There are two main types of canners available: boiling-water canners and steam-pressure canners.
Boiling-water canners are pots (usually made of aluminum, stainless steel, or other food-safe metals) that are large enough to hold jars with plenty of room to cover with water. Canners generally come with a rack, which keeps the jars from directly touching the base of the canner. A lid is placed on the canner during processing to retain heat. They are relatively inexpensive, but you can create a makeshift boiling-water canner using items that are probably already in your kitchen. Use a large pot that is wide enough to hold multiple jars and tall enough that the jars will fit with room to attach the lid if necessary. To keep the jars from touching the base of the pot, place a circular rack in the base of the pot so that jars do not come in direct contact with too much heat.
Steam-pressure canners are also large enough to hold jars, but they are only held in enough water to constantly create steam (2 to 3 inches). These canners also include a rack to keep the jar from directly touching the base of the canner and to keep the steam circulating during processing time. The lid is a crucial part of these canners. It tightly clamps in place. It has a gauge attached that measures the level of pressure inside the canner. For specific instructions on use, carefully read the manual of any steam-pressure canner you purchase before using.
Of course, the equipment is only part of the process—the most important thing is what you plan to can! Jellies and jams, sauces, pickles, and even soups can all be preserved for long-term storage. But, because of food safety concerns, it is always essential to follow the recipe to the letter. Canning is a science, and every teaspoon of acid, salt, sugar, or liquid impacts the safe preservation of your foods.
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