SPECIAL EQUIPMENT: canning jars and two-piece lids; wide-mouthed funnel (for filling jars with jam without making a mess); magnetic jar wand (to remove two-piece metal lids from boiling-hot water); jar lifter (safely lifts jars into and out of a boiling-water canner).
1. If you're going to make jams "shelf-stable," as opposed to storing them in the refrigerator, you will need to process the filled-and-closed jars in a boiling-water canner. This is the time to fill the canner with water and get it heating up on a back burner while you make jam. I'll walk you through "processing" in step 9.
2. Start with freshly washed canning jars and two-piece canning lids (available this time of year in most supermarkets and hardware-type stores). Wash them by hand in hot, soapy water, then give them a rinse and place the jars, bottoms up, on a towel-lined cookie sheet in a warm oven until needed.
3. To prepare lids, just follow manufacturer directions that came with them. Typically, you'll place them in a pot of water which you'll bring JUST to a boil then remove from the heat. Hot water softens up the sealing compound on the flat lids. Leave the lids in hot water until you use them.
4. Get all of your ingredients prepared and measured.
5. Start following directions in your recipe for preparing preserves. Recipes that come with packages of pectin usually are straightforward. Just make sure you handle each of the ingredients exactly as directed. Steps vary slightly, depending on whether you're using powdered or liquid pectin.
When combining fruit with other ingredients, some recipes tell you to use a "preserving pan," which simply is a heavy-bottomed pot that will heat evenly and keep fruit-and-sugar mixture from scorching on the bottom.
If making a jam without using commercial pectin like this Marionberry Jam recipe, you're relying on natural pectin in the fruit to produce a jell. This is the style of jam I prefer because I believe it has a richer flavor and a more natural, softer consistency.
Making jam without adding pectin means you have to boil the fruit and sugar until it reaches the "jell point" on your thermometer (see Testing Jams For Doneness below). The width of a pot affects the speed at which jam reaches the jell point. A wider pot — such as a 12-inch, cast-iron skillet — will cook jam faster. Fast is good when making jam without added pectin.
6. At this point, remove the pot from the burner and take a breath. Good for you, you've just made jam! I like to carefully move the pot over onto the counter and place it on a thick layer of potholders or a folded-up kitchen towel. The jam needs this time to settle down. If there's any foam on the surface, a lot will be reabsorbed during this two- to three-minute "rest." After that, skim off any foamy residue with a spoon. (TIP: To keep foam from forming in the first place, consider adding 1/4 to 1/2 teaspoon of butter or vegetable oil to the jam while it's cooking. Most recipes do not instruct you to do this, so you have to remember all by yourself. It works amazingly well and doesn't affect the flavor or safety of jam.).
7. Using a potholder, remove one of your clean jars from the oven and place it on the counter. Place your wide-mouthed funnel on top and ladle jam into the jar, filling to within 1/4 inch of the rim. You'll need to measure that distance in this first go-around, but then you'll have a visual image of how full the jars should be. Because even tiny, little splatters of jam on the jar rim can interfere with a good seal, dip a clean napkin or corner of a clean kitchen towel in some of the hot water that your lids are sitting in and wipe the jar rim.
8. Using your magnetic lid wand, fish out one of the flat metal discs from the pot of hot water. Shake off excess water and place it on the jar rim with the sealing-compound side against the rim. Next, remove one of the metal screw bands, shake off excess water and screw it down onto the jar. Screw firmly but not excessively. If you're planning to process jars in a boiling-water canner (see step 9), place filled and closed jar in the pot of hot water using a jar lifter. Repeat filling and closing all the jars, placing each one in the pot as it is filled and closed. You probably will run out of jam before you run out of jars.
9. Processing jars in a boiling-water canner (or not!): If you have enough refrigerator space, you can simply store jams in the refrigerator without further ado (after they've rested for several hours on the counter). They will hold their quality well beyond one year. But if you want to make your jams "shelf-stable," so they can be stored at room temperature without molding or otherwise suffering in quality, you need to process the jars in a boiling-water canner. In some cookbooks, this procedure is called a "boiling-water bath." Use a pot that is deep enough to ensure the jars are covered by at least 2 inches of water, and that there will be 2 inches of pan left to keep water from bouncing out while boiling.
When the jars are filled, lids screwed on and placed in the boiling-water canner, bring the water to a boil. Your recipe will give a processing time. Processing time begins once the water has reached a boil. After the jars have been "processed" for the required amount of time, remove them with your jar lifter and place them on a towel in a draft-free area of the kitchen.
10. Wait for the "ping." The most satisfying sound to a food preserver's ear is the telltale "ping, signifying that a vacuum has been formed, and the jar is sealing properly. The ping occurs as the lid is sucked down from its convex to concave position. It occurs anywhere between the first few moments after removing the jars from the canner up to an hour or so. After the jars have completely cooled, check seals by pressing down on each lid. If truly sealed, the surface will be solid and won't bounce back to your touch. Place unsealed jars in the refrigerator. (Typically, jars of jam will seal even if not put through the 10-minute processing in boiling water, so if putting jams in the refrigerator without processing, you may hear that "ping" anyway. But I've found that the seal on an unprocessed jar is not always as firm and reliable as one that forms after 10 minutes in boiling water.)
TESTING JAMS FOR DONENESS: With added pectin, jams, preserves and marmalades will be done when they are boiled according to the individual instructions given in the recipe.
Without added pectin, jam is done when it reaches 8 degrees ABOVE the boiling point of water. And remember, because water boils more quickly the higher you go on the planet, adjustments have to be made when determining the jelling point. The jelling point is 220 F from sea level up to 1,000 feet; 216 F up to 2,000 feet; 214 F up to 3,000 feet; 212 F up to 4,000 feet; 211 F up to 5,000 feet; 209 F up to 6,000 feet; 207 F up to 7,000 feet; and 205 F up to 8,000 feet.