Sugar-Free Blueberry-Strawberry Jam

Place 1 cup of the blueberries in an 8- to 10-quart heavy pot. Use a potato masher to crush the berries. Continue adding blueberries and the strawberries and crushing until you have 6 cups crushed berries. Stir in the water, lemon juice, and cinnamon. Gradually stir in pectin.

Bring berry mixture to a full rolling boil, stirring constantly. Boil hard 1 minute, stirring constantly. Remove from heat. Quickly skim off any foam with a metal spoon.

Ladle hot jam into hot, sterilized half-pint canning jars, leaving a 1/4-inch headspace. Wipe jar rims; adjust lids and screw bands.

Process filled jars in a boiling-water canner 10 minutes (start timing when water returns to boiling). Remove jars from canner; cool on wire racks.