4pintsblueberriesabout 8 cups you will need 4 cups of mashed fruit
1/2teaspoonbutterto reduce foaming (optional)
1 1/2ouncesliquid pectin like Certo1/2 pouch be sure to check the expiration date
You will also need 7 half-pint canning jars with lids and rings, wide-mouth funnel, canner and jar tongs.
Blueberries seem to not need as much pectin as other fruits to make jam. I use half the amount of pectin for blueberry jam as I do for strawberry jam. Maybe it is the natural pectin or maybe they don’t make as much juice.
Sterilize the jars and lids. Fill the canner about half full of water and turn heat on so that it will be boiling when you finish cooking the jam.
Wash blueberries, drain and put into a medium-sized mixing bowl. Chop and then mash blueberries until juice runs. Measure out 4 cups of mashed berries.
Measure 6 cups of sugar and put into a large stainless steel saucepan. Add berries, cinnamon and butter. Stir to mix.
Grate the lime zest and add to the berry/sugar mixture.
Bring berries and sugar to a full rolling boil that cannot be stirred down. Pay careful attention to the pot. It will boil over in a heartbeat and you don’t know what a mess is until you boil over blueberry jam
Stir in the ½ package of Certo. Return the mixture to another FULL, rolling boil that cannot be stirred down. Boil this for exactly 1 minute. I count “one-one-thousand, two-one-thousand, etc."
Remove jam from heat and pour into sterilized jars using a wide mouth funnel.
Fill each jar to ½ inch of the top. Wipe the tops of each jar and put on one of the sterilized lids. Secure with the lid ring. Using special canning jar tongs, put each jar into boiling water in the canner, making sure all jars are covered by the water.
Boil for 5 minutes, this is called processing. Remove jars using the tongs and cool on drying rack out of drafts