I used to make grape juice by cooking the grapes then filtering through cheesecloth. It was a long process but it made great grape juice. Then someone told me about a way to make juice with a LOT less effort and a LOT less time. In a nutshell you put the grapes in the jar with a little sugar (or none if you want) filling up the rest of the way with hot water, and processing in a water bath canner for 25 minutes. THAT'S IT, you are done! I've been making it this way now for about 10 years now, and don't plan on going back to a longer, harder process.
I grow concord, Catawba and Thompson Seedless but use the Concords and Catawbas for juice.
Ingredients per jar:
1 1/2 to 2 cups of grapes (I use 1 1/2 cups)
1/4 to 1/2 cup of sugar (I use 1/4 cup)
Boiling water to fill jar the rest of the way.
First wash your grapes well, I do it in the kitchen sink. Remove grapes from vine, and sort out bad grapes, stems, leaves, leaving just the good-quality grapes.
Prepare a pot of boiling water to use to fill the jars. You will need a little less than a quart for every quart of juice you are going to make.
Prepare your lids by boiling in water. I heat my washed jars in the microwave by placing a half inch of water into each jar and microwaving until the water boils. Then I use my 'hold warm' function on my microwave to keep them warm until ready to use. Or you could microwave them for a minute every few minutes to keep them hot.
Pour 1 1/2 cups of grapes and 1/4 cup of sugar into each jar.
Now pour the boiling water into the jar, leaving 1/2 inch of headspace, and place in water bath canner.
Process in boiling water bath for 25 minutes and you are done. This is so simple and makes great juice. When serving, pour slowly and usually the grapes will stay in the jar. Or you could pour over a strainer to keep the grapes out.