Serves: 7-8 cups of jam
cups crushed blueberries from about 2 quarts berries (slightly underripe berries work best)
teaspoon ground cinnamon
juice of half a lemon
- Combine the berries and sugar in a large, heavy pot over high heat. Cook, stirring frequently, until the berries have released a lot of juice and have just begun to simmer.
- Stir in the cinnamon, salt and lemon juice and return to a gentle, rolling boil. Boil the jam for about 40 minutes, stirring frequently, until it is quite thick and a small dollop spooned onto a plate and set aside to cool for a minute does not run when you tip the plate to one side.
- Fill 8 one-cup glass jars, sterilized according to the jar manufacturer’s instructions, and then process according to the manufacturer’s instructions.
- Once the jars have cooled, to make sure all of the lids are sealed, push down on the center of each. If the lid pops back up, the jar isn’t sealed; you should refrigerate and eat any jam in unsealed jars within a couple of weeks. Properly sealed jars will keep in a cool, dry place for several months.