I have been canning grape juice this week and will show you a few tips to make the job easier.
After picking the ripe grapes - wash them, remove the stems and sort out the unripe or shrivelled grapes.
Most recipes suggest you use a potato masher to release the juice. Your food processor is much easier. It allows you to process larger quantities at once.
The processor chops up the skins and pulp but leaves the seeds intact.
Now pour the juice into a large stockpot. Heat the grapes to boiling and simmer on medium heat for 10 minutes.
Pour cooked grapes into a juice bag. I made mine from unbleached cotton - I found cheesecloth too thin. I use a colander over a large pail to catch the juice.
I cover it and leave it settle overnight in a cool place such as the fridge or a cool porch or coldroom. The next day pour the juice slowly into a stockpot. Discard any sediment at the bottom of the pail. At this point, you can use some of the juice to make grape jelly.
Heat the juice to boiling point and pour into sterilized sealers. Process in hot water bath for 10 minutes.
From 2 containers of grapes, I got 10 quarts of grape juice to enjoy all winter.
You can either compost the remains in the juice bag or feed them to your chickens. :)