Ruby red grapefruits tend to get all the glory, but lately I've been relishing the white-fleshed yellow variety thanks to an abundant little grove of grapefruit trees near my mother-in-law's house in Southern California. The best yellow grapefruits have just the right balance of acid and sugar — not too sweet, not too puckery, and with a pleasant trace of bitterness. This makes for excellent marmalade and a nice change of pace from the standard orange kinds.
Growing just around the bend from these particular grapefruits is a cluster of elder trees — the inspiration for this grapefruit and elderflower marmalade. The delicate elderflower pairs beautifully with the citrus in a way that's subtly floral and refreshing. It won't hit you over the head, but it will give the preserves an extra note of warmth and sunshine.
White Grapefruit & Elderflower Marmalade
Adapted from Grapefruit Marmalade in Ball Complete Book of Home Preserving
Makes about 3 half-pint jars
1 large white or yellow grapefruit (preferably organic)
Pinch kosher salt
4 cups water, plus more for cooking the peels
3-4 cups granulated sugar
1/4 cup elderflower cordial
Wash the grapefruit. Cut off the top and bottom and discard. Score the peel into quarters and then carefully pull the peel off the grapefruit. Using a metal spoon, gently scrape and discard the bitter white pith from the backside of the peels. Thinly slice the peels. Place the peels in a large non-reactive saucepan, add a pinch of salt, and cover well with water. Bring to a boil over medium-high heat and boil for 10 minutes, periodically pushing the peels down with a wooden spoon. Drain and return the peels to the saucepan.
Working over a bowl, use a sharp knife to separate the grapefruit flesh from the membranes. After removing the flesh, squeeze any juice from the membranes. Add the flesh and juice plus 4 cups of water to the saucepan with the peels. Boil over medium-high heat for 10 minutes, stirring occasionally. Remove from heat, cover, and let stand for 12 to 18 hours.
Bring to a boil over medium-high heat and boil until the peel is tender, about 15 minutes. Remove from heat and measure the fruit mixture (there should be 3 to 4 cups). Measure out an equal amount of sugar. Spread the sugar on a baking sheet and heat it in a 200°F oven until warmed.
Return the fruit mixture to the saucepan and bring to a boil over medium-high heat. Add a small pinch of salt and stir in the warmed sugar. Cook at a rapid boil, stirring frequently, until it reaches a gel set, about 30 minutes. Stir in the elderflower cordial and boil for 30 seconds. Remove from heat and let stand for 5 minutes.
Ladle the marmalade into 3 sterilized half-pint jars, leaving 1/4-inch headspace. Seal and process in a boiling water bath for 10 minutes.