- Yield: 8 cups
- 2large pink or Ruby Red grapefruits, stem and blosson ends removed and discarded
- 2 thin-skinned lemons
- 6 1/2cups granulated sugar or more to taste
- Slice the grapefruits and lemons in half, squeeze out the juice through a small sieve into a medium, heavy-bottomed saucepan and reserve seeds. Using a sharp paring knife and your hands as needed, pull out the white membranes from the rinds, leaving, behind only the peels. Place the membranes and reserved seeds in a 15-inch square of double-thickness cheesecloth. Gather up the corners and tie them shut with kitchen string. Add to the saucepan.
- Slice the grapefruit and lemon peel into fine strips; add to the saucepan. Add 7 cups water and bring to a simmer over medium heat with the lid ajar. Continue simmering, stirring often and pressing the cheesecloth bag to release the pectin, until the peels turn to mush when pressed between fingers, 1 ½ to 2 hours. Remove the cheesecloth bag, and when cool enough to handle, squeeze any remaining juice from the bag into the saucepan. Discard bag. Measure the remaining liquid; there should be 7 cupsliters; if not, add water to make up difference or boil until reduced to this amount.
- Transfer the mixture to a clean, heavy-bottomed saucepan. Add the sugar and bring to a boil, stirring to dissolve the sugar. Taste and add additional sugar if you prefer a sweeter marmalade. Boil vigorously, stirring constantly, for 15 to 20 minutes, or until the mixture thickens and a candy thermometer reads 220F. If the marmalade “wrinkles,” it is set. Skim off any scum. Let stand in the saucepan for 5 minutes before ladling into hot, sterilized canning jars, leaving ¼ inch of headspace. Seal. Process the jars in a hot water bath for 5 minutes. When thoroughly cool, label jars. Store in a cool, dark place.
Reprinted with permission from Marmalade, © 2012 by Elizabeth Field, Running Press, a member of the Perseus Books Group.