Asparagus
From Wikipedia, the free encyclopedia
For the botanical genus, see Asparagus (genus). For the colour, see Asparagus (color).
| Asparagus officinalis | |
|---|---|
| A bundle of cultivated asparagus | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Asparagales |
| Family: | Asparagaceae |
| Subfamily: | Asparagoideae |
| Genus: | Asparagus |
| Species: | A. officinalis |
| Binomial name | |
| Asparagus officinalis L. | |
Asparagus officinalis is a spring vegetable, a flowering perennial[1] plant species in the genus Asparagus. It was once classified in the lily family, like itsAllium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and asparagus in theAsparagaceae. Asparagus officinalis is native to most of Europe, northern Africa and western Asia,[2][3][4] and is widely cultivated as a vegetable crop.
Biology
Asparagus is a herbaceous, perennial plant growing to 100–150 centimetres (39–59 in) tall, with stout stems with much-branched feathery foliage. The "leaves" are in fact needle-like cladodes (modified stems) in the axils of scale leaves; they are 6–32 mm (0.24–1.3 in) long and 1 mm (0.039 in) broad, and clustered 4–15 together. The root system is adventitious and the root type is fasciculated. The flowers are bell-shaped, greenish-white to yellowish, 4.5–6.5 mm (0.18–0.26 in) long, with sixtepals partially fused together at the base; they are produced singly or in clusters of two or three in the junctions of the branchlets. It is usually dioecious, with male and female flowers on separate plants, but sometimes hermaphrodite flowers are found. The fruit is a small red berry 6–10 mm diameter, which is poisonous to humans.[5]
Plants native to the western coasts of Europe (from northern Spain north to Ireland, Great Britain, and northwest Germany) are treated as Asparagus officinalis subsp. prostratus (Dumort.) Corb., distinguished by its low-growing, often prostrate stems growing to only 30–70 cm (12–28 in) high, and shorter cladodes 2–18 mm (0.079–0.71 in) long.[2][6] It is treated as a distinct species, Asparagus prostratusDumort, by some authors.[7][8] A remarkable adaptation is the edible asparagus, while in the Macaronesian Islands several species, (A. umbellatus, A. scoparius, etc.), are preserved the original form, a leafy vine; in the Mediterranean, the asparagus genus has evolved into thorny species.
Uses
| Nutritional value per 100 g (3.5 oz) | |
|---|---|
| Energy | 85 kJ (20 kcal) |
| Carbohydrates | 3.88 g |
| - Sugars | 1.88 g |
| - Dietary fibre | 2.1 g |
| Fat | 0.12 g |
| Protein | 2.2 g |
| Vitamin A equiv. | 38 μg (5%) |
| - beta-carotene | 449 μg (4%) |
| - lutein and zeaxanthin | 710 μg |
| Thiamine (vit. B1) | 0.143 mg (12%) |
| Riboflavin (vit. B2) | 0.141 mg (12%) |
| Niacin (vit. B3) | 0.978 mg (7%) |
| Pantothenic acid (B5) | 0.274 mg (5%) |
| Vitamin B6 | 0.091 mg (7%) |
| Folate (vit. B9) | 52 μg (13%) |
| Choline | 16 mg (3%) |
| Vitamin C | 5.6 mg (7%) |
| Vitamin E | 1.1 mg (7%) |
| Vitamin K | 41.6 μg (40%) |
| Calcium | 24 mg (2%) |
| Iron | 2.14 mg (16%) |
| Magnesium | 14 mg (4%) |
| Manganese | 0.158 mg (8%) |
| Phosphorus | 52 mg (7%) |
| Potassium | 202 mg (4%) |
| Sodium | 2 mg (0%) |
| Zinc | 0.54 mg (6%) |
| Link to USDA Database entry Percentages are relative to US recommendations for adults. Source: USDA Nutrient Database | |
Only young asparagus shoots are commonly eaten: once the buds start to open ("ferning out"), the shoots quickly turn woody.[13]
Water makes up 93% of Asparagus`s composition.[14] Asparagus is low in calories and is very low in sodium. It is a good source of vitamin B6, calcium, magnesium and zinc, and a very good source of dietary fibre, protein, vitamin A, vitamin C, vitamin E, vitamin K, thiamin, riboflavin, rutin,niacin, folic acid, iron, phosphorus, potassium, copper, manganese and selenium,[15][16] as well as chromium, a trace mineral that enhances the ability of insulin to transport glucose from the bloodstream into cells.[citation needed] The amino acid asparagine gets its name from asparagus, as the asparagus plant is relatively rich in this compound.
The shoots are prepared and served in a number of ways around the world, typically as an appetizer[17] or vegetable side dish. In Asian-style cooking, asparagus is often stir-fried. Cantonese restaurants in the United States often serve asparagus stir-fried with chicken, shrimp, or beef. Asparagus can also be wrapped in bacon. Asparagus may also be quickly grilled over charcoal or hardwood embers. It is also used as an ingredient in some stews and soups. In recent years, almost as a cycle dating back to early culinary habits, asparagus has regained its popularity eaten raw as a component of a salad.[18]
Asparagus can also be pickled and stored for several years. Some brands may label shoots prepared this way as "marinated".
Stem thickness indicates the age of the plant, with the thicker stems coming from older plants. Older, thicker stalks can be woody and peeling the skin at the base will remove the tough layer. Peeled asparagus will poach much faster, however.[19] The bottom portion of asparagus often contains sand and dirt, so thorough cleaning is generally advised before cooking it.
Green asparagus is eaten worldwide, though the availability of imports throughout the year has made it less of a delicacy than it once was.[6] In Europe, however, the "asparagus season is a highlight of the foodie calendar"; in the UK this traditionally begins on 23 April and ends on Midsummer Day.[20][21] As in continental Europe, due to the short growing season and demand for local produce, asparagus commands a premium.
[edit]White asparagus in continental northwestern Europe
Asparagus is very popular in the Netherlands, Spain, France, Poland, Belgium, Germany, and Switzerland, and almost exclusively white—else, it is specified by the local language term for "green asparagus". Compared to the latter, the locally cultivated so-called "white gold" or "edible ivory", also referred to as "the royal vegetable",[12] is less bitter and much more tender. Freshness is highly regarded, and it must be peeled before cooking or raw consumption.
To cultivate white asparagus, the shoots are covered with soil as they grow: without exposure to sunlight there is no photosynthesis, and the shoots remain white in colour.
Only seasonally on the menu, asparagus dishes are advertised outside many restaurants, usually from late April to June. For the French style, asparagus is often boiled or steamed and served with hollandaise sauce, melted butter or olive oil, Parmesan cheese or mayonnaise.[22] Tall, narrow asparagus cooking pots allow the shoots to be steamed gently, their tips staying out of the water.
During the German Spargelsaison or Spargelzeit, the asparagus season that traditionally finishes on 24 June, roadside stands and open air markets sell about half of the country's white asparagus consumption.[23]
[edit]Medicinal
The second century physician Galen described asparagus as "cleansing and healing".[citation needed]
Nutrition studies have shown asparagus is a low-calorie source of folate and potassium. Its stalks are high in antioxidants.[citation needed] "Asparagus provides essential nutrients: six spears contain some 135 micrograms (μg) of folate, almost half the adult RDI (recommended daily intake), 20 milligrams of potassium," notes an article in Reader's Digest.[citation needed]
Research suggests folate is key in taming homocysteine, a substance implicated in heart disease. Folate is also critical for pregnant women, since it protects against neural tube defects in babies. Studies have shown that people who have died from Alzheimer's Disease have extremely low to no levels of folate. Several studies indicate getting plenty of potassium may reduce the loss of calcium from the body.
Particularly green asparagus is a good source of vitamin C.[citation needed] Vitamin C helps the body produce and maintain collagen, the major structural protein component of the body's connective tissues.
"Asparagus has long been recognized for its medicinal properties," wrote D. Onstad, author of Whole Foods Companion: A Guide for Adventurous Cooks, Curious Shoppers and Lovers of Natural Foods. "Asparagus contains substances that act as a diuretic, neutralize ammonia that makes us tired, and protect small blood vessels from rupturing. Its fiber content makes it a laxative, too."
Water from cooking asparagus may help clean blemishes on the face if used for washing the face morning and night.[citation needed] From John Heinerman's Heinerman's New Encyclopedia of Fruits and Vegetables: "Cooked asparagus and its watery juices are very good for helping dissolve uric acid (causes gout) deposits in the extremities, as well as inducing urination where such a function may be lacking or only done on an infrequent basis. Asparagus is especially useful in cases of hypertension where the amount of sodium in the blood far exceeds the potassium present. Cooked asparagus also increases bowel evacuations."
South Korean scientists discovered asparagus can help with hangovers. Research to be published in the Journal of Food Science, says extracts taken from leaves and shoots were found to boost levels of key enzymes that help break down alcohol.[24]
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