
A grapefruit slice is a cut piece of grapefruit, the large round citrus fruit of Citrus × paradisi, used as a garnish.
Fresh citrus aroma sits over a tart, characteristically bitter flesh whose sweetness varies with the variety.
A garnish for visual and aromatic accent rather than a measured ingredient, cut close to service and set on the rim or floated to signal the drink and lift grapefruit-citrus aroma at the nose; dehydrated slices serve as a shelf-stable version that holds colour and shape.
Another pink or red citrus slice can restore the colour and visual cue; the specific pomelo-orange hybrid aroma is hard to match, and only a closely related citrus such as pomelo approximates it.
Pomelo
The pomelo (Citrus maxima) is one of the grapefruit's parent species: it is larger, with thicker rind and pith, and its flesh is milder, less acidic and less bitter than grapefruit.
Cut from a citrus hybrid descended from a cross between the pomelo and the sweet orange, the fruit's flesh ranges from pale yellow through pink to deep red by variety. For garnish it is prepared in several cut forms — fresh wheels or slices, wedges, half-moons, or dehydrated dried slices.
Fresh-cut slices are perishable — the exposed flesh oxidises and dries at the cut surface — so cut them close to service; dried slices keep at room temperature.
Grapefruit is generally held to have originated in Barbados as an accidental hybrid, first documented in the 18th century.