Canning #4: Grape Jam

After our success canning urban applesauce, we were alerted to a backyard arbor of unwanted Concord grapes.

So, like any normal person would do, we picked 40 pounds.

Concord grapes have seeds, so to get them out of your jam, you peel the grapes (they just squirt out of their skins), cook the skins and insides separately, mill the insides to get the seeds out, and put it all back together. I used this recipe.

(Yes, we peeled 40 pounds of grapes. By "we," I mostly mean Erica.)

I cooked them in small batches, using every pot in the house (multiple times), burning a few, and learning a lot about jam making.

Twelve hours later, we had 12 half pints of jam, 8 pints of jam, and 3 quarts of grape sorbet base, and EVERYTHING IN THE WORLD was purple and sticky. Somehow, I ended up with jam on my feet.

P.S. What's the difference between grape jam and grape jelly? Jam has actual chunks of the fruit fiber in it; jellies are made from just the strained fruit juice.

P.P.S. The grape sorbet (recipe), once I recovered enough to freeze it, was also incredibly delicious.

Digression: Jam recipes vary a lot in how much sugar they call for. Epicurious says 1 cup per pound of grapes. The recipe I used called for 1/4 cup per pound of grapes. Low-sugar jam! But! You cook jam until it reaches 220 degrees F. What allows it to come to a temperature higher than the boiling point of water is that it's reached a certain concentration of sugar (something like 65%). So it seems to me that all finished jams have the same amount of sugar, and adding less at the start just means you're going to spend more time cooking it down -- and that you'll have finessed the proportions of fruit sugar to processed sugar (which is not necessarily an insignificant thing). Am I missing something here?