- canning jars (use jars made specifically for canning, such as Ball or Mason jars) and two-part lids (consisting of one-time use flat lids and reusable rings)
- a pot large enough for your jars to stand up in with an inch of water covering them
- a canning funnel (or other wide-mouth funnel)
- jar-grabber tongs
- an assistant
A great resource for home canning is here: http://www.uga.edu/nchfp/index.html
Now, onto jam specifically:
Before you start, put on Bob Marley. Then sterilize your jars (boil for 10 minutes or as manufacturer indicates) and prepare the lids according to the manufacturer's directions. The actual jamming process depends on your recipe, which depends on your sugar preferences. If you want to make old-fashioned strawberry jam, here's a classic recipe:
4 c. mashed berries
4 c. sugar
1/4 c. lemon juice
- Mix all ingredients together and cook and cook and cook(stirring constantly all the while) until it reaches 220 F.
- Fill jars (4-5 half-pint jars or 2 pint jars), leaving 1/4 inch headspace.
- Place lids on and screw down bands to finger-tight.
- Process (boil) jars in large pot for 10 minutes.
- Remove jars and let cool. Lids will suck down (you'll hear them pop) as they cool. Any jars that don't seal should be used immediately. (Try it on ice cream!)
For the blackberry and strawberry jams we made today we used "Pomona's Universal Pectin," which worked wonderfully. The two great things about this pectin are that you only have to cook the fruit for about 5 minutes total and you can use as little as 3/4 c. of sugar. For something like strawberries, that was just perfect-- the jam is plenty sweet and very fruity. For the blackberries we used more sugar, about 1 and 1/2 cups.
To illustrate the steps:
Step 1: Boil berries with sweetener as per recipe.
Steps 2-3: Fill jars and screw lids on. (The canning funnel makes this a lot easier.)
Step 4: Boil.
Step 5: Let cool. (Strawberry jam is in the front jars, blackberry in the back.)