Pectin is a naturally occurring substance in fruit that makes sweet preserves thicken. 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.
You will be removing the citrus zest, the colored part of the rind. Set it aside for another use such as limoncello. The zest is wonderfully aromatic and flavorful, but it could overwhelm the flavors of other fruits in your jams and jellies (especially if you aren't making a citrus jam) and it doesn't bring any pectin to the party. Be aware that this pectin can have a little bitterness to it, so it's best to use in preserves that have spices or very flavorful fruits rather in more subtle preserves.
- 1/2 pound citrus peels (white parts)
- 1/4 cup lemon juice
- 2 cups water
Gather the ingredients.
Remove the colorful zest of the peels with a zester or vegetable peeler and set aside for other uses or discard.
Cut off the white piths, finely chop them, and weigh them, ensuring you have 1/2 pound.
In a medium pot, combine the chopped citrus peel pith with the lemon juice. 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 is now ready to use. You can keep it in the refrigerator for a week, or in the freezer for 6 months.
You might find your pectin is not as concentrated as you would like. One way to test the strength of the pectin is to take a tablespoon of it and drop it in a bowl with a couple of tablespoons of rubbing alcohol. Let it sit for a minute and then see if you can pick up the glob of pectin with a fork. If you can't, you can reduce the liquid in your remaining batch of liquid pectin by heating it to a boil, uncovered, until it is more concentrated.
Homemade citrus pectin for making preserves is completely different from modified citrus pectin, which is the subject of medical research. Pectin is nondigestible fiber, while modified citrus pectin is specially processed to be digestible. You are not able to do this at home.
Memorial Sloan Kettering Cancer Center. Pectin. Updated July 3, 2019.