Lemon and orange, and to a lesser extent lime and grapefruit, are much used for flavoring. The zest of citrus fruit—the outer, colored part of the rind—contains its essential oil, which is highly aromatic, far more than the juice within. Pared or grated, zest brings liveliness to any concoction, whether savory or sweet (just be sure to avoid the bitter white pith). The cook can also rub a lump of sugar against the outside of a lemon or orange, for the sugar to absorb some of its oil. Another method, when making sweet bread, is to rub one’s hands against the fruit and then immediately knead the dough to impart some of the oil’s delicate fragrance.