In a food processor or blender, combine blueberries and apple juice concentrate; blend until liquefied. Pour into an 11- by 17-inch aking pan. Cover and freeze until firm around the edges, about 2 hours.
With a heavy spoon, break frozen mixture into pieces. In a food processor or blender container, place mixture and blend until smooth but not completely melted. Spoon into a 9-by 5-inch loaf pan; cover and freeze until firm. Serve within a few days.
Nutritional analysis, per serving: calories, 112; fat, 1g; carbohydrate, 28g; protein, 1g; calories from fat, 8%