To make homemade grape juice, rinse and de-stem the grapes and mash them with a potato masher. Cook the grapes and continue mashing them to break up as many of the remaining grapes as possible. Strain the grape mixture into a large pot using a cheesecloth or fine mesh sieve.
Use concord grapes to make this homemade grape juice, though you may use scuppernongs and muscadines as well. Wash and de-stem the grapes individually and throw away green, overripe or old and shrivelled grapes.
Mash about 4 pounds of grapes at a time. You can add some water so that the grapes mixture is thin enough to strain easily. Some people add about 1/2 a cup of sugar to the grape mixture before boiling it.
When cooking the grapes, put them on medium heat until they are almost boiling and then simmer for about 10 minutes. Stir the grapes mixture occasionally so that it does not stick to the bottom of the pan. When sieving the grape juice, use two layers of cheesecloth on a large pot and secure them with a rubber band. It is advisable to place the pot on a plate to catch any juice that runs over. Let the grapes mixture sit on the cheesecloth overnight to strain completely.
After straining the juice completely, remove the cheesecloth, rinse it and sieve the juice again to remove sediments that form at the bottom of the large pot. Pour the juice into glasses and enjoy.