Grapefruit peel, cover with water and boil purposes under the hood for 2 hours. As cool ground with a meat grinder or food processor. The resulting slurry was measured and 1 cup mash, add 1 cup sugar. Boil for 15-20 minutes, the foam was harvested, jam pour into sterilized jars that turn upside down until it cools down. Option: Instead of 4 grapefruit grapefruit put 2 and 3 lemons, grapefruit or 2, 2 lemons and 2 small limes. * The jam has a spicy, slightly bitter streak, which to me very much like - fried slices of super.