I have been meaning to post this for a while so it would be of use when grapes were in season, but I guess late is better than never. Right? I love making jelly. It is a little time consuming but it makes me feel all old-timey, which is perfect for an historian. The trick to jelly is cooking it for long enough for it to set, otherwise you just get grape juice. As their name suggests, I can't get Concord grapes here because they are rather specific to a certain locality. Up here, we have Coronation grapes. (I took the above pic from here because all mine turned out like crap) They can survive the cold weather and still pack a major grapey punch. This jam is seriously intense, and is amazing on multigrain toast for breaky.
As with all jams and jellies, you will need sterilized jars and lids, and a large canning pot with boiling water to process the final product.
So, to make jelly, you first need to make some juice. Wash and drain the berries and remove from the stem. Place in a large pot with 1/4 cup or so of water for every 4 cups of berries. Bring to boiling, then reduce heat and cook for 10 mins, stirring and crushing the grapes. When grapes are all soft, remove from pot and drain in a colander lined with a few layers of damp cheesecloth for at least 2 hours. I found that one 2L basket of grapes ended up making about 4 cups of juice, which turned into two 500 ml jars of jam.
So, now that you have the juice you can make jelly. You will need for cups of juice and 3 cups of sugar to make two 500 ml jars of jam. Combine the two ingredients in a large pot and bring to the boil. This jelly will foam up like crazy, so make sure it only takes 1/4 of the volume of the pot. You can see in the pic above how high the jam rose. Boil hard for 20 to 25 mins, until the jam sheets from a spoon. I was never sure what this meant until I made this jam. Basically, when the jam is ready it will drip off the spoon like you see in the pic below.
Pour the jelly into jars, screw on the lids finger tight, then process for 10 minutes in the boiling water. When done, remove from heat and remove lid. After 5 mins, remove jars from the water and cool.