1/2 gal. Grade A Medium Amber pure maple syrup
3 cups cold water
2 teaspoons Genugel (pectin does not work with maple syrup). Genugel is available from maple syrup equipment suppliers.
Whisk the Genugel into the cold water first, then add to syrup.
Make sure the pot is at least 3 times the size of the liquid, as it foams up during boil.
Boil all ingredients to 217.5 degrees F. (Some people go to 219, but that makes unnecessarily hard jelly and wastes more content).
Here is the tricky part - The objective is to make clear jelly in the jar. Any infusion of air through stirring or filling of the jars will put air bubbles into the jelly. It will still taste fine, but won't look as good. It helps greatly to keep a low flame under the jelly while bottling, as this stuff gels really fast and heat keeps it liquid longer.
First, skim off the surface foam as minimally as possible. A lot of waste can occur at this point.
Second, have a cup or ladle large enough to fill each clean jar with ONE pour.
If you have to go back and add more to fill the jar, you will have air bubbles and layering.
Cap the filled jars and process them in a hot water bath for 10 minutes at 180 degrees.
Depending on how good you are at skimming, a half gallon of syrup will net you five to seven 8 ounce jars of maple jelly.
Yield is low and many people don't think it's worth the syrup or the trouble.
Massachusetts Maple Producers Assn