The cross-section of a citrus fruit reveals nearly everything you need to know about a lemon, lime, orange, or grapefruit. Here's how to use each part to your advantage.
A citrus fruit's fragrant and flavorful essential oil is contained in the skin. Use it to your advantage: Finely zest the skin for use in baked goods, shave off a wide strip with a sharp vegetable peeler and twist it over a cocktail, or candy it for a great homemade gift.
The spongy, white, pectin-rich layer underneath the citrus skin is bitter and inedible; it can be especially hard to remove from a grapefruit. For easier peeling, place whole grapefruit in a pot of hot water for a few minutes, then remove and let cool; the heat will help separate the peel and pith from the flesh.
The flesh of a citrus fruit can range from sweet (orange) to tart (grapefruit) to downright sour (lemons and limes). To cut perfect segments (also known as "supremes") of oranges, grapefruits, or even the sweet Meyer lemons, try this technique: Slice off the top and bottom of the fruit, then cut away the peel and pith in thick, vertical strips. Slice along the sides of each segment to release it from the membranes.