Asparagus

Asparagus is a member of the lily family. Native to the Mediterranean, asparagus is now grown all over the world. Surprisingly, there are about 300 varieties of asparagus, but only 20 are edible. Asparagus has fleshy spears topped with budlike, compact heads. It is usually harvested in the spring when it is 6 to 8 inches tall. Normally green or greenish purple in color, white asparagus is grown underground to inhibit its development of chlorophyll content in order to provide a more delicate flavor and color for a unique culinary experience.

HISTORY

Asparagus originated in the eastern Mediterranean region, as well as in northern and southern Africa. There is evidence that it was first cultivated in ancient Egypt, where it was prized not only as a food but also for its medicinal properties. Today, asparagus is cultivated in most subtropical and temperate parts of the world, with the majority of commercially available asparagus grown in the United States, Mexico, Peru, France, Spain, and other Mediterranean countries.

NUTRITIONAL HIGHLIGHTS

Asparagus is low in calories and carbohydrates, but relatively rich in protein compared to other vegetables. One cup of asparagus supplies only 24 calories, almost half of which are derived from protein. Asparagus is an excellent source of potassium, vitamin K, folic acid (263 micro-grams per cup), vitamins C and A, riboflavin, thiamin, and vitamin B6; and it has an excellent ratio of potassium (288 milligrams per cup) to sodium (19.8 milligrams per cup). Asparagus is also a very good source of dietary fiber, niacin, phosphorus, protein, and iron.

HEALTH BENEFITS

Asparagus has historically been used in the treatment of arthritis and rheumatism, and as a diuretic. The diuretic effect of asparagus may be due to the amino acid asparagine, which when excreted in the urine gives off a strong, characteristic odor. The benefit in arthritis may be the result of recently identified unique phytochemical antioxidants (racemofuran, asparagamine A, and racemosol) as well as inhibitors of the COX-2 enzyme, which produces inflammatory compounds.

HOW TO SELECT AND STORE

The best-quality asparagus is firm and the tips are closed. In general, the darker the stalk, the higher the concentration of nutrients. Once trimmed and cooked, asparagus loses about half its total weight, so buy about one-half pound per person when purchasing this vegetable fresh for use as part of a main dish.

Asparagus is perishable and loses many nutrients, as well as its flavor, if it is not used within a day or two after purchasing. To maintain freshness as long as possible, store in the refrigerator with the ends wrapped in a damp paper towel.

TIPS FOR PREPARING

Wash asparagus under cold running water and gently scrub with a vegetable brush. If it is not organically grown, soak in cold water with a mild solution of additive-free soap or use a produce wash (see page 50) and rinse.

Asparagus is most often prepared by lightly steaming the entire spear, or cutting the spear diagonally and stir-frying. Snap off the tough stem ends of the asparagus by holding a spear in both hands and bending; it will break where the tender and tough parts meet. Be sure to wash asparagus under cold water to remove any sand or soil residues before cooking.

If you love asparagus and eat it often, invest in an asparagus steamer, a tall, narrow steamer that allows asparagus to be cooked to perfection. Avoid cooking asparagus in an iron pot, as the tannins in the asparagus can react with the iron and cause the stalks to become discolored. After cooking, asparagus can be served hot or cold. If your recipe calls for cold asparagus, plunge the stalks into cold water immediately after cooking, then remove them quickly; letting them soak too long can cause them to become soggy.

Roasting asparagus is another simple and flavorful technique. Simply mix asparagus with an oil or oil-based vinaigrette and your favorite herbs and spices. Place it in a roasting dish and bake at 400 degrees F. for 10 minutes. If other vegetables are added, be sure that they cook quickly or are thinly sliced, given the short cooking time of this dish.

QUICK SERVING IDEAS

Asparagus can be roasted alone or along with other vegetables, such as yams, squash, and potatoes.

Chilled, steamed asparagus served with a light lemon vinaigrette makes a delightfully refreshing salad.

Steamed asparagus can be puréed with broth and seasoning to make a delicious soup.

Add steamed asparagus to freshly cooked pasta and toss along with navy beans, olive oil, thyme, tarragon, and rosemary.

Finely chopped raw asparagus makes a flavorful and colorful addition to omelets.

Stir-fry asparagus with garlic, shiitake mushrooms, and chicken (or tofu).

SAFETY

People not familiar with asparagus are often alarmed by the strong odor coming from their urine after eating it. Several different chemicals contribute to the smell, most notably asparagine. Different people form different amounts of these chemicals after eating asparagus, and many people cannot smell the odor, even when they produce the chemicals.

Asparagus contain low amounts of oxalate. Individuals with a history of oxalate-containing kidney stones should avoid overconsuming this food. For more information, see Appendix D, page 787.

Asparagus contains a moderate amount of purines, so individuals with gout should limit their consumption of this food.