Nutrition: Citrus are low-calorie nutritional powerhouses. One medium orange contains about 60 calories – and 120 percent of the adult daily dose of vitamin C. A mandarin contains about 45 calories; a whole grapefruit, 105. A lemon has just 17 calories; a lime has 20. Besides vitamin C, all citrus are high in fiber and other nutrients such as calcium and potassium. One cup (8 ounces) of orange juice has 100 calories and 150 milligrams of vitamin C.
Selection: Citrus fruit do not ripen off the tree; they must reach maturity and full ripeness before harvest. Look for firm, unblemished fruit with bright color and finely textured, smooth skin. A juicy orange or lemon should feel heavy for its size. Avoid fruit with soft spots, dull or faded coloring, or wrinkled, saggy skin.
Storage: Keep fresh citrus unpeeled in the refrigerator. It will keep for several weeks. Rinse with cool water and pat dry before peeling. When cut, store in a sealed nonmetallic container or zip-locked bag in the refrigerator.
Preparation: Peel and eat (or cook); that’s it for most citrus. For an easy-peeling orange, roll the fruit under your palm on a hard surface. This loosens the skin, so the peel will come right off.
Canning: Peel and separate citrus into sections. Remove the white pith and any membrane. Pack the sections into sterilized jars and cover the fruit with light syrup (made with equal parts sugar and water, brought to a boil). Allow a half-inch of head space at the top of the jar. Seal and process in a boiling hot water bath for 10 minutes.
Juice it: An average lemon or lime contains 2 tablespoons juice. Valencia oranges, the world’s most popular orange, have twice as much juice as navel oranges, the king of California citrus. Depending on the size of the fruit and variety, each orange yields 2 to 4 ounces of juice.
Use citrus juice instead of vinegar in marinades and salad dressings; the juice’s acidity naturally tenderizes meat, fish or poultry.
Freezing: Citrus sections can be frozen in their own juice. Separate the segments, then cover with fresh juice in a freezer container, allowing a half-inch head space. Frozen segments should keep their quality for six months.
Juice also can be frozen for up to six months. Pour lemon or lime juice into an ice cube tray, then freeze solid. Transfer the juice cubes to a zippered bag or other container. Each cube will be 1 ounce (or 2 tablespoons), equal to the juice of one lemon or lime.
Freeze the zest, too. Grate the peel and spread onto a cookie sheet. Freeze, then transfer to a plastic bag. But don’t freeze whole fruit; it will expand and burst, making a big mess in the freezer.
Pick your own: If you have a citrus tree in your backyard, the best place to “store” fruit is usually on the tree. They’ll keep for months, even after they reach full color. To test for ripeness, give the fruit a gentle squeeze. If it feels rock-hard and solid, it needs more time. If it has a little give, it’s juicy and ripe. But don’t wait forever; if left too long, citrus will start to dry out and be all pulp, no juice.