The recipe I followed was at Chef in You found here: Grape Jam
During mid September I send my kids out every few days to bring me a big bowl of grapes. When I have 2 hours and The Office on Netflix, I make up a batch of jam.
Next, rinse, stem, and peel the grapes. It's not as bad as it sounds. Concord grapes are slipskin, meaning with a little squeeze they come right out of their jackets. But save the skins - you'll need them.
Bring the skinned grapes to a boil in a deep pan, and cook over medium heat for about 10-15 min till they break down and the seeds start to separate from the pulp. Strain out the seeds and return the juice and pulp to the pan. Bring up to med-high heat.
Add the skins in to the boiling grapes. I have done the skins in two ways. I have left them intact and I have pulsed them in the food processor first. I prefer pulsing them first but you can do it either way.
Cook for about 5 min and then add 3 cups of sugar. Cook and stir constantly till the jam thickens. It takes me about 20 min to get to the right stage. I use the spoon test and fridge test. From the Chef in You site, here's how to test for doneness:
How to check if your Jam is done?
1. Temperature Test – If the temperature (using a candy thermometer) shows 220ºF (or 104ºC), then the Jam is done. Make sure that your thermometer is placed vertically and the bulb is covered with the jam. The bulb should NOT touch the bottom of the pan.
2. Spoon Test – This is similar to how you test a sugar thread consistency. Take a cool metal spoon and dip it into the boiling Jam mixture. When you life the spoon, if the Jam runs off the spoon like a syrup, then the Jam needs more cooking time. But if it is heavier and drops like slate/sheet off the spoon instead of flowing as drops, you know that the Jam is done.
3. Refrigerator Test - I mostly use this method to check the doneness of my jams. I keep a plate in the freezer and remove it when I want to test. I then pour a small amount of the boiling jelly/jam on this plate and let it sit in the fridge for few seconds. If the mixture gels /mounds and wrinkles when you push it with your finger, it's done. If runny and it does not have a body to it, then continue to cook the jam for few more minutes until it clears the nudge test.
My biggest problem was estimating amounts. The recipe is based on three lbs of concord grapes. I literally guessed. I peeled grapes till the pile of skins overflowed my smallest metal bowl (I'm recording this so I know for future reference). This recipe makes 2 1/2 finished pints. I did not have good results when trying to double the recipe.
That's it. No pectin, just grapes and sugar. This jam is more flavorful than Welch's, and amazingly beautiful. It's thick and rich. A pb&j with this stuff is a real treat!
I have some in the fridge.
Some in the freezer to slow the kid's consumption down.
And some canned (processed for 15 min). Love it!