When your garden or farmers' market is overflowing with fresh summer fruits and vegetables, the urge to can it for colder months takes hold. Test kitchen contributor Nicki Sizemore demonstrates the basics of hot-water canning, a simple method for sealing your preserved food so they'll keep at room temperature for up to a year.
Nicki demonstrates the method on a fresh berry syrup, but the same principles apply to any other high-acid preserved food.
More recipes that use the hot-water canning method:
The Hot Water Canning Method
First, you heat your empty Mason jars in a large pot of simmering water, and heat the lids in a smaller pot of very hot water to soften the flange. Keep the jars' metal bands out of the water bath; they should stay cool because you'll be touching them.
Remove and empty the hot jars. Pour the syrup into the jars, leaving about 1/4 inch of headroom (headroom varies from about 1/4 to 1/2 inch, depending on what you're canning; check your recipe for the specifics). Wipe the rims of any spilled syrup, put the lids on, and screw on the bands. Don't tighten the bands too much, or it may interfere with the jars sealing.
Put the jars in a pot fitted with a rack insert, and add enough water to cover by 2 inches. Bring to a boil over high heat; once the water comes to a boil is when you start counting the "processing time" specified in your recipe.
Transfer the jars to a rack and allow them to cool for 12 to 24 hours. You should hear a popping sound as the vacuum seals the lid to the jar.
When the jars are competely cool, check the seals by pressing on the lids. The lids should be taut and pulled down toward the inside of its jar. If a lid bounces when you press on it, the seal is imperfect, and you'll need to either reprocess with a new lid, or simply refrigerate your preserves and use it up within two weeks.