8 cups raspberries, blackberries, blueberries or hulled strawberries
1 (16 ounce) can apple juice concentrate
Reduce the concentrate by pouring thawed apple juice into a 5- to 6-quart pan. Boil rapidly, uncovered, until reduced to 1 1/4 cups, 4 to 8 minutes.
Rinse berries, drain dry and put into a 15 x 10-inch baking pan. If using strawberries, slice them.
Mix fruit and reduced concentrate and bake uncovered in a 375 degree F oven until berries release juice, about 10 minutes.
Meanwhile, put a ceramic saucer in the freezer.
Reduce oven temperature to 325 degrees F.
Every 20 minutes or so, gently stir berries to moisten well with juice. Bake until a little berry liquid spooned onto a chilled saucer doesn't flow together when you pull the tip of a spoon or your fingertip through it (as you lift the spoon or your finger, the liquid holds on, forming a small droplet). This should take about 1 hour for blueberries and 1 to 1 1/2 hours for other berries.
Let jam cool; if necessary, reheat and adjust consistency.
Spoon into bowl or small jars.
Serve, or cover airtight and chill up to 2 weeks.
Yields about 1 1/2 cups raspberry or blackberry jam or 2 1/2 cups blueberry jam