About the Recipe
5 cups freshly washed blackberries (or parts by weight)
1 cup white granulated sugar* (or parts by weight)
1 tablespoon lemon juice
Pectin (optional, but gels faster – follow directions on package)
Crush blackberries in a large pot. A potato masher works well.
Add sugar and lemon juice, turn heat to medium low, and simmer until jam starts to gel.**
Make sure to stir consistently to keep the foaming and bubbles down.***
Pour into pint jars and refrigerate or water bath for longer storage.****
Blackberries are naturally high in pectin, but it takes longer to cook it down enough that it gels correctly. If it doesn’t gel, it wasn’t cooked long enough, then you have syrup. Blackberry syrup? Not a bad thing!
*This is a very berry tasting jam, not high in sugar and takes longer to cook for a good gel. A standard full sugar blackberry jam is equal parts blackberries to equal part sugar (5:5). The more the sugar, the higher the yield and faster it will gel (try 5:4, 5:3, 5:2 - find your preference).
**You can test the gel by putting a small amount on a pre-cooled saucer and cooling it in the fridge to test the consistency (remove from heat while testing). If after a few minutes it is the consistency you prefer, it is done. If it is still liquid, you need to cook it longer. Undercooking will make syrup. Although still yummy and useful, it isn’t jam.
***Some people like to use butter to help reduce the foaming but remember, anything with oil can eventually go rancid. National Center for Food Preservation notes, “Adding 1/2 teaspoon of butter or margarine with the juice and pectin will reduce foaming. However, these may cause off-flavor in long-term storage of jellies and jam."
****To water bath, fill pint jars with1/2 inch headspace, wipe the rims and put on lid seals, and water bath for 10 minutes. Don’t disturb jars for at least 48 hours to help with the gelling process. Makes 2+ pints of jam (depending on how much sugar you use).
Note: If any of your bottled jam goes to “sugar,” you can always warm it up in a pan on the stove and make it delicious and useable again.