Prep 20 mins
Cook 20 mins
While fresh blackberries, or even boysenberries, will give you the best results, this can be made with frozen berries if in a JAM (pun intended). Times are estimates. High altitude instructions are included.
- 1 quart fresh blackberries (unsweetened, loose-pack) or 1 quart frozen blackberrie, thawed (unsweetened, loose-pack)
- 1⁄4 cup fresh lemon juice
- 4 1⁄2 cups sugar
- 1 1⁄2 teaspoons lemon zest, finely grated
- 1⁄4 teaspoon ground cinnamon
- cinnamon stick
- Combine the berries and lemon juice in a heavy 4-qt saucepan. Bring to a boil over medium-high heat, stirring often.
- Stir in the sugar, lemon zest, and cinnamon, and allow the mixture to boil to dissolve the sugar.
- Reduce the heat to medium. Boil gently for about 15 minutes, stirring often, until the temperature on a candy thermometer reaches 220F (substract 2F degrees for each 1,000 feet above sea level).
- Remove pot from the heat. With a long-handled spoon, stir the jam and skim off any foam that rises to the top.
- Ladle the jam into hot, sterilized half-pint canning jars, leaving a 1/4-inch space on top. Place a piece of cinnamon stick in the jam in each jar. Seal the lid according to the manufacturer's instructions.
- Cool the jars upright on a wire rack. Store in the refrigerator for up to 1 month.
- For longer storage, process the jars in a boiling-water bath for 5 minutes after sealing. Add an additional minute of processing time for each 1,000 feet above sea level.
- Cool on a rack and label. Store the jars in a cool, dry, dark place.