This is just about the easiest and most foolproof jam to make.Adding some lemon improves both the flavor and the consistency of the jam.The added pectin from the lemon rind ensures good setting.
Testing jam for setting: Before starting to cook your batch of jam, put a small bowl or saucer in the freezer. Once the jam is a few degrees away from setting temperature, remove it from the heat and put a tablespoon of the mixture in the chilled bowl. Return it to the freezer for 5 minutes, then remove and check the temperature and consistency with a fingertip. The idea is to get the spoonful of jam to cool to room temperature at which point it should be softly set. If it's too watery, repeat the test after another couple of minutes of cooking.
2 pounds/about 3 pints blueberries, washed and dried weight
2 cups water
1 lemon quartered, seeds removed
1 1/2 pounds sugar
- Bring berries and water to a boil in a large Dutch oven; lower heat and simmer 15 minutes.(Cool overnight and resume the next day if you wish.)
- Return to a boil and stir in lemon and sugar.Return to a boil, stirring occasionally.
- Cook, stirring often, for 10 minutes, or until it reaches jelled temperature, about 220 degrees on a candy thermometer.Remove lemon before pouring the jam into sterilized jars.