It seems to be a peculiarity of the citrus family that extremely different fruits find themselves grouped under a single name. Think "tangerine," which includes everything from the pinkie-sized Kishu to some of the new varieties such as the Yosemite Gold that are as big as an orange.
And then there's grapefruit.
In markets today you can find grapefruit and grapefruit kin of all different colors and sizes, from pale gold to deep ruby, from cocktail grapefruit that's no bigger than an orange to pummelos that are as big as your head.
And while grapefruit hasn't quite ascended the peaks of trendiness that blood oranges or mandarins have, their distinctive flavor makes them a terrific ingredient in winter desserts and salads, particularly for those cooks not afraid of a little tart. (That flavor comes from a chemical compound so identified with the fruit that it's called "grapefruit mercaptan.")
There are some special grapefruit varieties to look out for. The traditional white Marsh grapefruit has terrific very tart flavor and usually comes along later in the season; if you find it, buy it. Star Rubys have probably the best flavor of any of the red grapefruits. And Oroblanco, a cross between a pummelo and a grapefruit, is sweeter and less tart than most grapefruit.
How to choose: Choose grapefruit by their heft — they should be heavy for their size. And by their smell — lightly scratch the peel with your thumbnail and you should get a good whiff of perfume. Other than that, the peel tells you little: Ripe fruit can still have a trace of green and a scarred rind does not affect the flavor.
How to store: Because their peels are so thick, grapefruit can be kept at cool room temperature for several days. Refrigerate if they start to show signs of softening.
Need some ideas for how to use them? Here are 12 great recipes from our California Cookbook that use grapefruit as a featured ingredient.