| Asparagus officinalis | |
|---|---|
 | |
| Wild asparagus in Austria | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Monocots |
| Order: | Asparagales |
| Family: | Asparagaceae |
| Genus: | Asparagus |
| Species: | A. officinalis |
| Binomial name | |
| Asparagus officinalis L. | |
| Nutritional value per 100 g (3.5 oz) | |
|---|---|
| Energy | 85 kJ (20 kcal) |
| Carbohydrates | 3.88 g |
| Sugars | 1.88 g |
| Dietary fiber | 2.1 g |
| Fat | 0.12 g |
| Protein | 2.20 g |
| Thiamine (Vit. B1) | 0.143 mg (11%) |
| Riboflavin (Vit. B2) | 0.141 mg (9%) |
| 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%) |
| Vitamin C | 5.6 mg (9%) |
| Calcium | 24 mg (2%) |
| Iron | 2.14 mg (17%) |
| Magnesium | 14 mg (4%) |
| Phosphorus | 52 mg (7%) |
| Potassium | 202 mg (4%) |
| Zinc | 0.54 mg (5%) |
| Manganese 0.158 mg | |
| Percentages are relative to US recommendations for adults. Source: USDA Nutrient database | |
Contents
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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 millimetres (0.24–1.3 in) long and 1 millimetre (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 millimetres (0.18–0.26 in) long, with six tepals partially fused together at the base; they are produced singly or in clusters of 2–3 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 centimetres (12–28 in) high, and shorter cladodes 2–18 millimetres (0.079–0.71 in) long.[2][6] It is treated as a distinct species, Asparagus prostratus Dumort, by some authors.[7][8]
History
Asparagus has been used from early times as a vegetable and medicine, owing to its delicate flavour and diuretic properties. There is a recipe for cooking asparagus in the oldest surviving book of recipes, Apicius’s third century AD De re coquinaria, Book III. It was cultivated by the ancient Egyptians, Greeks and Romans, who ate it fresh when in season and dried the vegetable for use in winter. Asparagus is pictured on an Egyptian frieze dating to 3000 BC. France’s Louis XIV had special greenhouses built for growing it.[9]It lost its popularity in the Middle Ages, but returned to favour in the seventeenth century.[10]
Uses
Culinary
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 fiber, protein, vitamin A, vitamin C, vitamin E, vitamin K, thiamin, riboflavin, rutin, niacin, folic acid, iron, phosphorus, potassium, copper, manganese and selenium[citation needed], 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, the asparagus plant being rich in this compound.
The shoots are prepared and served in a number of ways around the world, typically as an appetizer[11] 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, and also 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 the French style, it is often boiled or steamed and served with hollandaise sauce, melted butter or olive oil, Parmesan cheese or mayonnaise. Tall, narrow asparagus cooking pots allow the shoots to be steamed gently, their tips staying out of the water. 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.[12]
Asparagus can also be pickled and stored for several years. Some brands may label shoots prepared this way as "marinated".
The bottom portion of asparagus often contains sand and dirt, so thorough cleaning is generally advised in 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] However, in the UK, due to the short growing season and demand for local produce, asparagus commands a premium and the "asparagus season is a highlight of the foodie calendar."[13] In continental northern Europe, there is also a strong seasonal following for local white asparagus, nicknamed "white gold".
Medicinal
The second century physician Galen described asparagus as "cleansing and healing".Nutrition studies have shown asparagus is a low-calorie source of folate and potassium. Its stalks are high in antioxidants. "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. 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. 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. 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." It should be noted, however, that ammonia only "makes us tired" if we are in end stage liver failure.
Cultivation
See also: List of asparagus diseases
Since asparagus often originates in maritime habitats, it thrives in soils that are too saline for normal weeds to grow. Thus, a little salt was traditionally used to suppress weeds in beds intended for asparagus; this has the disadvantage that the soil cannot be used for anything else. Some places are better for growing asparagus than others. The fertility of the soil is a large factor. "Crowns" are planted in winter, and the first shoots appear in spring; the first pickings or "thinnings" are known as sprue asparagus. Sprue has thin stems.[14]White asparagus, known as spargel, is cultivated by denying the plants light while they are being grown. Less bitter than the green variety, it is very popular in the Netherlands, France, Belgium and Germany, where 57,000 tonnes (61% of consumer demand) are produced annually.[15]
Purple asparagus differs from its green and white counterparts, having high sugar and low fibre levels. Purple asparagus was originally developed in Italy and commercialised under the variety name Violetto d'Albenga. Since then, breeding work has continued in countries such as the United States and New Zealand.[verification needed]
In northwestern Europe, the season for asparagus production is short, traditionally beginning on April 23 and ending on Midsummer Day.[16]
Companion planting
Asparagus is a useful companion plant for tomatoes. The tomato plant repels the asparagus beetle, as do several other common companion plants of tomatoes. Meanwhile, asparagus may repel some harmful root nematodes that affect tomato plants.[17]Commercial production
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Vernacular names and etymology
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". Asparagus was also corrupted in some places to "sparrow grass"; indeed, the Oxford English Dictionary quotes John Walker as having written in 1791 that "Sparrow-grass is so general that asparagus has an air of stiffness and pedantry". In Gloucestershire and Worcestershire, it is also known simply as "grass", and young plants too small to cut are called "pru"[citation needed]. Another known colloquial variation of the term, most common in parts of Texas, is "aspar grass" or "asper grass". In the Midwest United States and Appalachia, "spar grass" is a common colloquialism. Asparagus is commonly known in fruit retail circles as "Sparrows Guts", etymologically distinct from the old term "sparrow grass", thus showing convergent language evolution.[citation needed]
It is known in French and Dutch as asperge, in Italian as asparago (old Italian asparagio), in Portuguese as aspargo, in Spanish as espárrago, in German as Spargel, in Hungarian as spárga.
The Sanskrit name of Asparagus is shatavari and it has been historically used in India as a part of Ayurvedic medicines. In Kannada, it is known as ashadhi, majjigegadde or sipariberuballi.
In Thailand it is known as no mai farang (Thai: หน่อไม้ฝรั่ง), and in Vietnam măng tây which literally mean "European bamboo shoots" and "Western bamboo shoots", respectively. The green asparagus is normally used in Thai cuisine.
Urine effects
The effect of eating asparagus on the eater's urine has long been observed:- "[Asparagus] cause a filthy and disagreeable smell in the urine, as every Body knows." (Treatise of All Sorts of Foods, Louis Lemery, 1702)[24]
- "asparagus... affects the urine with a foetid smell (especially if cut when they are white) and therefore have been suspected by some physicians as not friendly to the kidneys; when they are older, and begin to ramify, they lose this quality; but then they are not so agreeable" ("An Essay Concerning the Nature of Aliments," John Arbuthnot, 1735)[25]
- Asparagus "...transforms my chamber-pot into a flask of perfume." Marcel Proust (1871–1922) [26]
Chemistry
The volatile organic compounds responsible for the smell are identified as:[33][34]
- methanethiol
- dimethyl sulfide
- dimethyl disulfide
- bis(methylthio)methane
- dimethyl sulfoxide
- dimethyl sulfone
The onset of the asparagus urine smell is remarkably rapid. It has been estimated to start 15 to 30 minutes after ingestion.[36][37]
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