Grapefruit marmalade has an intense flavor and marked bitterness—mostly from the white pith beneath the skin. In this jam recipe, we opt for small grapefruits because they have less pith so you'll end up with less-bitter results.
Nutrition per serving may change if servings are adjusted.
2 small red organic grapefruit (about 12 ounces each), washed and dried
2½ cups granulated sugar
2 cups water
Place a saucer and 2 small spoons in the freezer for testing the marmalade thickness later.
Cut 1 inch off both ends of each grapefruit and reserve. Cut the fruit into very thin round slices. Coarsely chop half the slices; cut the remaining slices into quarters. Reserve any seeds. Reserve any juice that accumulates on the cutting board.
Wrap the reserved ends and seeds in a double layer of cheesecloth and tie closed. Place in a large nonreactive pot (see Tip). Add the fruit, the reserved juice, sugar and water. Cook over medium heat, stirring frequently, until the sugar is completely dissolved, 2 to 3 minutes.
Increase heat to high and boil rapidly, stirring frequently and scraping the bottom with a heatproof spatula to prevent sticking, until the mixture thickens and most of the fruit separates from the peels, about 15 minutes. Remove from heat.
To test, place a little of the liquid (without any solids) on a frozen spoon. Rest it on the saucer and return to the freezer for 3 to 4 minutes. Then drop the sample onto the saucer: if it's thick enough to mound without quickly running or spreading, the marmalade is ready. If it's runny, return the pot to a boil and cook for another 3 to 5 minutes before testing again.
When the marmalade passes the thickness test, discard the cheesecloth bag. Let cool completely before serving or refrigerating.
To make ahead: Refrigerate for up to 1 month.
Tips: Be sure to use a nonreactive potstainless-steel, enamel-coated or glasswhen working with acidic food like grapefruit. Reactive vessels, such as aluminum and cast-iron, can impart off colors and/or flavors.
65 calories;0 g fat(0 g sat); 0 g fiber; 17 g carbohydrates; 0 g protein; 1 mcg folate; 0 mg cholesterol; 17 g sugars; 16 g added sugars; 116 IU vitamin A; 4 mg vitamin C; 2 mg calcium; 0 mg iron; 1 mg sodium; 18 mg potassium