This recipe comes from "Preserving the Taste by Edon Wycott." I found it on the cooking channel site. Emeril Lagasse used it in his strawberry recipe. Remember this has to be made at least a day ahead of time before you make your jam.
2 pounds of underripe green apples, washed and cut into eights depending on size (not peeled or cored)
4 cups of water
This makes about 1-2 cups of pectin
In a large saucepan, over high heat, bring the apples and water to boil.
Reduce the heat to medium and simmer until the apples are soft and fall apart , about 20 minutes. Line a sieve with a cheesecloth and put sieve in a large bowl ( the drained juice should not touch the sieve) . Let it drain for several hours or overnight. Measure the apple juice and pour in a pot. Bring the liquid to a boil and cook until reduced by half. Refrigerate and use within 4 days or freeze for up to 6 months.
I made this recipe twice to get the amount I needed