Zest is a food ingredient that is prepared by scraping or cutting from the outer, colorful skin of unwaxed citrus fruits such as lemon, orange, citron, and lime. Zest is used to add flavor to foods.
In terms of fruit anatomy, the zest is obtained from the flavedo (exocarp) which is also referred to as zest. The flavedo and white pith (albedo) of a citrus fruit together makes up its peel. The amounts of both flavedo and pith are variable among citrus fruits, and may be adjusted by the manner in which they are prepared. Citrus peel may be used fresh, dried, candied, or pickled in salt.