Asparagus
2007 Schools Wikipedia Selection. Related subjects: Food and agriculture
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| Asparagus officinalis L. |
Asparagus is a type of vegetable obtained from one species within the genus Asparagus, specifically the young shoots of Asparagus officinalis. It has been used from very early times as a culinary vegetable, owing to its delicate flavour and diuretic properties. There is a recipe for cooking asparagus in the oldest surviving book of recipes, Apicius's 3rd century CE De re coquinaria, Book III.
White asparagus is cultivated by denying the plants light and increasing the amount of ultraviolet light exposed to the plants while they are being grown.
The English word "asparagus" derives from classical Latin, but the plant was once known in English as sperage, from the Medieval Latin sparagus. This term itself derives from the Greek aspharagos or asparagos, and the Greek term originates from the Persian asparag, meaning "sprout" or "shoot." The original Latin name has now supplanted the English word. Asparagus was also corrupted in some places to "sparrow grass"; indeed, John Walker stated in 1791 that "Sparrow-grass is so general that asparagus has an air of stiffness and pedantry." It is commonly known in fruit retail circles as "Sparrows Guts", etymologically distinct from the old term "sparrow grass" showing convergent language evolution.
In their simplest form, the shoots are boiled or steamed until tender and served with a light sauce like hollandaise or melted butter or a drizzle of olive oil with a dusting of Parmesan cheese. A refinement is to tie the shoots into sheaves and stand them so that the lower part of the stalks are boiled, while the more tender heads are steamed. Tall cylindrical asparagus cooking pots have liners with handles and perforated bases to make this process foolproof.
Unlike most vegetables, where the smaller and thinner are the more tender, thick asparagus stalks have more tender volume to the proportion of skin. When asparagus have been too long in the market, the cut ends will have dried and gone slightly concave. The best asparagus are picked and washed while the water comes to the boil. Meticulous cooks scrape asparagus stalks with a vegetable peeler, stroking away from the head, and refresh them in ice-cold water before steaming them; the peel is often added back to the cooking water and removed only after the asparagus is done, this is supposed to prevent diluting the flavor. Small or full-sized stalks can be made into asparagus soup. Cantonese restaurants in the United States often serve asparagus stir-fried with chicken, shrimp, or beef. Asparagus is one of few foods which is considered acceptable to eat with the hands in polite company, although this is more common in Europe.
Some of the constituents of asparagus are metabolised and excreted in the urine, giving it a distinctive, mildly unpleasant odour. The smell is caused by various sulfur-containing degradation products (e.g. thiols and thioesters). Studies showed that about 40% of the test subjects displayed this characteristic smell; and a similar percentage of people are able to smell the odour once it is produced. There does not seem to be any correlation between peoples' production and detection of the smell. The speed of onset of urine smell is rapid, and has been estimated to occur within 15-30 minutes from ingestion.
The amino acid asparagine gets its name from asparagus, the asparagus plant being rich in this compound.
Nutrition
Asparagus is one of the more nutritionally valuable vegetables. It is the best vegetable provider of folic acid. Folic acid is necessary for blood cell formation and growth, as well as liver disease prevention. Folic acid is also important for pregnant women as it aids in the prevention of neural tube defects such as spina bifida in the developing fetus. Asparagus is also very low in calories; each stalk contains fewer than 4. It contains no fat or cholesterol, and is very low in sodium. Asparagus is a great source of potassium and fibre. Finally, the plant is a source of rutin, a compound that strengthens the walls of capillaries.
Popularity
Peru is currently the world’s leading asparagus exporter, followed by China and then Mexico -
The top asparagus importers in 2004, by quantity, were the United States (92,405 tons), followed by the European Union-25 (EU-25) (external trade) (18,565 tons), and Japan (17,148 tons), according to Global Trade Atlas and U.S. Census Bureau statistics. The United States imported more than four times the amount than the EU-25, the next largest importer.
The United States production for 2005 was on 54,000 acres and yielded 90,200 tons making it the world's largest producer and consumer when import quantities are factored in. Production was concentrated in California, Michigan & Washington states.
Importers in the United States import both green fresh asparagus and white fresh asparagus from Peru. While both green and white fresh asparagus from Peru are marketed in the United States, the colour requirements of the current U.S. Standards for Grades of Fresh Asparagus only provide for the grading of green asparagus.
Other plants called asparagus
Many related and unrelated plants may be called "asparagus" or said to be "used as asparagus" when eaten for their shoots. In particular, the shoots of a distantly related plant, Ornithogalum pyrenaicum, may be called "Prussian asparagus". See Category:Stem vegetables.