Very often I’ll need the juice of half of a lemon for something; the remaining shell need not be neglected. The peel is, in many ways, the most interesting and useful part of a citrus fruit. It contains the fragrant, flammable citrus oil, and a lot of handy pectin to boot. There are a few different uses for citrus peels, and they require different preparation. Lime peels are an exception to a lot of the rules of citrus peels… you can’t dry or candy them (a difference in the chemical composition of their skins makes them turn brown and leathery). You can, however, shave the zest off and save it in the freezer until you have another use for it. I feel compelled to mention that I have read some very alarming reports about pesticides used on citrus fruit trees seeping into the oil of citrus fruits, making the peel of conventionally grown citrus a bit questionable. For whatever its worth, I only use the peels of organic citrus.
To dry citrus peels:
Use a vegetable peeler to shave off the outer layer of peel. With a needle and thread string the strips of peel onto a length of string. Hang the string of peels up in a well ventilated area, and the peels will dry in a few days. Dried peels can be stored indefinitely in spice jars. Dried strips of citrus peel can be added to stocks or soups to brighten the flavor, You can also use them to make your own flavored tea. You can turn the dried strips into powder them by whizzing them for a few seconds in an electric coffee grinder. The resulting powder can be added to baked goods or sprinkled on top of a cappuccino.
To save citrus peels for marmalade:
If you only need the juice of an orange or lemon, you can use a course grater to remove the zest and some of the peel from the outside of the fruit. Then you can juice the fruit as you normally would. Again, wrap the zest well and freeze it until you have enough to make the preserves of your choice.
To save citrus peels for candying or jams:
Scrape away the inside of the fruit so that all you have left is the spongy white peel. Throw it in a bag in the freezer until you have accumulated enough to make a batch of candied peels (I promise to post a recipe once we reach prime citrus fruit season).