Pectin is a naturally occurring substance in fruit that makes sweet preserves gel. However, some fruits are low in pectin and need added pectin in order to gel. You can buy commercial pectin, or you can make your own from citrus peels. You can also make pectin from apples.
High-pectin citrus peel is what makes marmalade gel without added pectin. Keep in mind that it is the white pith or inner part of the citrus peel that is rich in pectin. Under-ripe fruits have more of this pith than fully ripe fruits. You can use any citrus for this recipe, but grapefruit works especially well because of its larger pith.
Be sure to use organically grown fruit because you don't want pesticides in your pectin!
- 1/2 pound white parts of citrus peels
- 2 cups water
- 1/4 cup lemon juice
Remove the colorful zest of the peels with a zester or vegetable peel. Set aside for another use such as limoncello. The peels are wonderfully aromatic and flavorful, but they could overwhelm the flavors of other fruits in your jams and jellies, and they don't bring any pectin to the party.
Cut off the white piths, finely chop, and weigh.
Combine the chopped citrus peel pith with the lemon juice in a medium-sized pot. Let stand for 2 hours. Add the water and let stand for another hour.
Bring the mixture to a boil over high heat. Reduce heat and simmer for 15 minutes. Remove from heat and let cool.
Strain through a jelly bag or several layers of cheesecloth. The liquid pectin will keep in the refrigerator for a week, or in the freezer for 6 months.