
Orange peel is the outer rind of the orange (Citrus × sinensis), used in drinks as an aromatic garnish and flavouring rather than as a beverage.
Fragrant citrus oil dominates, bright and orange-scented; the white pith beneath adds an unwanted bitterness if left on.
A single strip is expressed over the surface of a finished drink, oils squeezed skin-side down to spray a citrus aroma across the top, then often dropped in as garnish. The albedo is trimmed away to avoid bitterness, and the aroma is strongest immediately after expression.
Another citrus peel with expressible flavedo oils, such as lemon, can stand in with a shift of aromatic character; the specific orange note cannot be reproduced by a non-citrus garnish or by orange juice, which lacks the volatile peel oils.
A twist is a strip of peel cut from the flavedo and expressed over or into the drink to release its oils, then often dropped in as garnish; grated zest is finely shredded flavedo mixed into a preparation. Both come from the same flavedo but differ in form and technique.
Cut from the fruit as a strip, the peel is made up of two layers: the coloured outer flavedo, which holds the aromatic essential-oil glands, and the white spongy albedo beneath, which is bitter and generally excluded. Its aromatic character comes from oils held in the flavedo, released when the peel is twisted or squeezed.
The volatile flavedo oils dissipate once the peel is cut; expressing a fresh twist to order gives the most aroma.