A sugar-free blueberry jam recipe from Ball / Bernardin.
1 kg (7 cups) of whole blueberries, after mashing, will equal about 1 litre (4 cups) of mashed. A tidge over or under is fine. But if you measured your berries by weight, you won't be too far off that.
If using frozen blueberries, zap from frozen in microwave for 4 to 5 minutes, then mash, retaining any juice that might have come off while thawing.
Don't crush or mash the berries in a machine, it will damage the pectin.
For the fruit juice, you can use cranberry, apple, grape, etc.
How much stevia you need will depend on the tastes of your crowd and how sweet / tart that particular batch of blueberries was.
If you are using the Ball No Sugar Needed pectin from a canister, you'll want 3 level tablespoons.
Ball / Bernardin No Sugar Needed is the same; it's made in the same plant and just labelled with different names on the packaging.
Boil hard means it should bubble for the whole 3 minutes.
You could also use the 125 ml (1/2 cup) smaller sampler size jars. But this recipe hasn't been tested for larger 1/2 litre (1 US pint) jars.
Blueberry Jam Sugar-Free (Ball / Bernardin). www.healthycanning.com