The peel is the outer layer of protection on a fruit. In the case of citrus fruits, the peel is bitter and typically not consumed raw. However, the zest, or the colored outermost layer of the peel, can be scraped off and used to add a tangy flavor to dishes.
The white, fleshy part of the peel is bitter when raw, but can be made sweet through a candying process that involves boiling it with sugar. This recipe can be adapted to many different types of citrus fruits, including oranges, lemons, limes, and grapefruits.