Never use the white part of the peel of a lemon for flavoring. It is
bitter. The little globules of oil in the surface of the rind contain
all the pleasant flavor of the peel. It may be thinly pared off,
avoiding the white pulp. Professional cooks, however, rub loaf-sugar
over the surface. The friction breaks the oil-ducts, and the sugar
absorbs the oil. It is called zest. The sugar is afterward pounded fine
for certain dishes, such as creams, _meringues_, etc.; or it can be
simply melted in custards and beverages.