How to Can Jam at Home
As they cooland sometimes even as you remove them from the canneryour lids will "ping." This is a sign they're sealing and your canning has been a success. As hard as it may be to wait, it's not recommended that you check your seals until the jars have had time to fully cool. Once cool, you can press the center of each lid with your finger. If the lid does not depress under the pressurethink of a Snapple lidyou've got a seal.
Homemade jams can be kept in a cool, dark pantry as long as the seal has not been compromised, but should be consumed within a year or two for best quality.
A naturally-occuring substance found in most fruits, pectin is what makes jams, jellies and preserves thick. When heated, pectin interacts with both the natural sugars in the fruit and any sugar you've added to your jam and jelly recipes, thickening the final product. Though the recipe in this post uses powdered pectinwhich can be purchased in single serving boxes or bulk containerspectin is also available for purchase in liquid form, andif you're feeling adventurousyou can make your own. Apple peels, such as those left over from a big batch of applesauce, are one of the best commonly available sources. Homemade, liquid and bulk pectin can be tricky though, so if you're just starting out you might want to stick with a pre-measured, single-serving box of the powdered stuff.
Looking for more canning tips, tricks and recipes? Our Practice of Preserving series will run throughout the year. From Home Canning Safety to putting by meat, we'll have a new feature each month to help you make the most of 2012's bounty!