In response to many requests, I shall quote from "Put a Lid On It" verbatim.
"For the adventurous purist or the economy-minded with an ample supply of apples, pectin making is an interesting and satisfying project. Apple pectin impacts a delicate apple flavor to any jam made from it. Making your own pectin lets you create small batches of unusual jams like pear-blueberry and mango-kiwi. The pectin content of apples decreases with storage so make this in the fall when apples are at their freshest.
7 tart apples (about 2 lbs)
4 cups water
2 tbsp lemon juice
Cut apples into quarters (do not peel or core). Combine with water and lemon juice in a large stainless steel or enamel saucepan. Bring to a boil over high heat, cover, reduce heat and simmer for 40 minutes, stirring occasionally. Strain through a coarse sieve and discard solids. Pour liquid through a jelly bag or several layers of cheesecloth. Ladle into sterilized 1 cup jars and process 5 minutes from reboil in BWB. Makes 4 cups.
To Use Homemade Apple Pectin for Jams or Jellies
For each 1 cup of finely chopped fruit or juice use 1 cup Homemade Apple Pectin and 3/4 cup of sugar. Combine in a stainless steel or enamel saucepan with 1 tsp lemon juice if fruit is low acid. Bring to a boil over high heat and boil HARD, stirring constantly until mixture will form a gel (about 10 minutes). Ladle into sterilized jars and process five minutes from reboil in BWB."
This method has worked great for me and, personally, I don't notice any apple flavor being imparted to most jams I have made using it. I made 24 jars of it last year and used them all up in February when nectarines and apricots showed up in the grocery store at a good price. The resulting jam (I called it Sunshine Jam because it was SO pretty) was amazing!!!
It's also nice to have on hand because most stores don't seem to stock pectin year round so now you can make jam or jelly ANYTIME!!!