Rhubarb: Wikis

Advertisements
  
  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

From Wikipedia, the free encyclopedia

Rhubarb
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Caryophyllales
Family: Polygonaceae
Genus: Rheum
Species: R. rhabarbarum
Binomial name
Rheum rhabarbarum
L.
Rhubarb, raw
(Rheum rhabarbarum)
Nutritional value per 100 g (3.5 oz)
Energy 88 kJ (21 kcal)
Carbohydrates 4.54 g
Sugars 1.1 g
Dietary fibre 1.8 g
Fat 0.2 g
Protein 0.9 g
Water 93.61 g
Folate (Vit. B9) 7 μg (2%)
Vitamin C 8 mg (13%)
Vitamin E 0.27 mg (2%)
Vitamin K 29.3 μg (28%)
Calcium 86 mg (9%)
Iron 0.22 mg (2%)
Potassium 288 mg (6%)
Sodium 4 mg (0%)
Zinc 0.1 mg (1%)
Percentages are relative to US recommendations for adults.
Source: USDA Nutrient database

Rhubarb is a group of plants that belong to the genus Rheum in the family Polygonaceae.

They are herbaceous perennial plants growing from short, thick rhizomes. They have large leaves that are somewhat triangular shaped with long fleshy petioles. They have small flowers grouped in large compound leafy greenish-white to rose-red inflorescence.

While the leaves are toxic, the plants have medicinal uses, but most commonly the plant's stalks are cooked and used in pies and other foods for their tart flavour. A number of varieties have been domesticated for human consumption, most of which are recognised as Rheum x hybridum by the Royal Horticultural Society.

Contents

Cultivation

Rhubarb is now grown in many areas and thanks to greenhouse production is available throughout much of the year. Rhubarb grown in hothouses (heated greenhouses) is called hothouse rhubarb. This rhubarb is typically made available at consumer markets in February and March, before outdoor cultivated rhubarb is available. Hothouse rhubarb is usually a brighter red than cultivated rhubarb. Hothouse rhubarb is also more tender and tastes sweeter than cultivated rhubarb.[1] In temperate climates rhubarb is one of the first food plants to be ready for harvest, usually in mid to late spring (April/May in the Northern Hemisphere, October/November in the Southern Hemisphere), and the season for field-grown plants lasts until September. In the northwestern US states of Oregon and Washington, there are typically two harvests: one from late April to May and another from late June and into July. Rhubarb is ready to be consumed as soon as it is harvested, and freshly cut stalks will be firm and glossy.

In warm climates, rhubarb will grow all year round, but in colder climates the parts of the plant above the ground disappear completely during winter, and begin to grow again from the root in early spring. It can be forced, that is, encouraged to grow early, by raising the local temperature. This is commonly done by placing an upturned bucket over the shoots as they come up. Because rhubarb is a seasonal plant, obtaining fresh rhubarb out of season is difficult in colder climates, such as in the UK.

Rhubarb can successfully be planted in containers, so long as the container is large enough to accommodate a season's growth.

The colour of the rhubarb stalks can vary from the commonly associated crimson red, through speckled light pink, to simply light green. Rhubarb stalks are poetically described as crimson stalks. The colour results from the presence of anthocyanins, and varies according to both rhubarb variety and production technique. The colour is not related to its suitability for cooking:[2] The green-stalked rhubarb is more robust and has a higher yield, but the red-coloured stalks are much more popular with consumers.[citation needed]

Advertisements

Historical cultivation

Rhubarb displayed for sale at a grocery store

Rhubarb has been used for medical purposes by the Chinese for thousands of years and appears in the The Divine Farmer's Herb-Root Classic which is traditionally attributed to Shen Nung, the Yan Emperor, but is thought to have been compiled in about 2700 BC.[3]

The plant has grown wild along the banks of the River Volga for centuries but this variety was known to the west as Russian rhubarb, as opposed to the more efficacious Chinese rhubarb. The expense of transportion across Asia caused rhubarb to be highly expensive in medieval Europe where it was several times the price of other valuable herbs and spices such as cinnamon, opium and saffron. The merchant explorer, Marco Polo, was therefore much interested to find the plant being grown and harvested in the mountains of Tangut province.[3]

The term rhubarb is a combination of the Greek rha and barbarum; rha is a term that refers both to the plant and to the River Volga.[4] Rhubarb first came to the United States in the 1820s, entering the country in Maine and Massachusetts and moving westwards with the European US-American settlers.[5]

Uses

Rhubarb is grown primarily for its fleshy petioles, commonly known as rhubarb sticks or stalks. The use of rhubarb stems as food is a relatively recent innovation, first recorded in 17th century England, after affordable sugar became available to common people, and reaching a peak between the 20th century's two world wars.

Cooking

One way is to cut up the stalks into one-inch pieces and stew them (boil in water); it is only necessary to just barely cover the stalks with water because rhubarb stalks themselves contain a great deal of water; add 1/2 to 3/4 cup of sugar for each pound of rhubarb,[1] then add cinnamon and/or nutmeg to taste. Sometimes a tablespoon of lime juice or lemon juice is added. The sliced stalks are boiled until soft.

At this stage, cooked with strawberries or apples as a sweetener, or with stem or root ginger, rhubarb makes excellent jam. Other fruits, with the addition of pectin (or using sugar with pectin already added), can also be added to rhubarb at this stage to make a variety of jams: the fruit is added at a ratio of two parts fruit to one part rhubarb, consisting of strawberries or raspberries, or chopped plums, apricots, or apples. Boiling should continue for at least ten minutes after all fruit is completely softened, depending on whether a simple refrigerated jam is made, or if (with longer cooking) jam is to be bottled for a long shelf life.

To make a "sauce," of rhubarb (to which dried fruit could be added near the end) continue simmering 45 minutes to one hour at medium heat, until the sauce is mostly smooth and the remaining discrete stalks can easily be pierced with a fork, which yield a smooth tart-sweet sauce with a flavor similar to sweet and sour sauce. This sauce is called rhubarbsauce, analogous to applesauce. Like applesauce, this sauce is usually stored in the refrigerator and eaten cold. The sauce, when stewed over medium heat only a short time (about 20 minutes) and with only a little water so that the rhubarb stalks stay mostly discrete, may be used as filling for pies (see rhubarb pie), tarts, and crumbles. Sometimes stewed strawberries are mixed with the rhubarb to make strawberry-rhubarb pie. This common use has led to the slang term for rhubarb, "pie plant". It can also be used to make wine.

In former days, a common and affordable sweet for children in parts of the United Kingdom and Sweden was a tender stick of rhubarb, dipped in sugar. It is still eaten this way in western Norway, and other parts of the world. In the UK the first rhubarb of the year is harvested by candlelight in dark sheds dotted around the noted "Rhubarb Triangle" of Wakefield, Leeds and Morley,[6] a practice that produces a sweeter, more tender stalk.[7]

A homemade rhubarb pie

Medicine

Rhubarb can be used as a strong laxative, with the roots being used as a laxative for at least 5,000 years.[8] Rhubarb has an astringent effect on the mucous membranes of the mouth and the nasal cavity.[9]

The roots and stems are rich in anthraquinones, such as emodin and rhein. These substances are cathartic and laxative, which explains the sporadic use of rhubarb as a slimming agent.

Rhubarb roots are used in traditional Chinese medicine; rhubarb also appears in medieval Arabic and European prescriptions.[10][11]

The rhizomes ('roots') contain stilbene compounds (including rhaponticin) which seem to lower blood glucose levels in diabetic mice.[12]

Toxic effects

Rhubarb flower

Rhubarb leaves contain poisonous substances, including oxalic acid which is nephrotoxic and a corrosive acid that is present in many plants. The LD50 (median lethal dose) for pure oxalic acid in rats is about 375 mg/kg body weight,[13] or about 25 g for a 65 kg (~140 lb) human. While the oxalic acid content of rhubarb leaves can vary, a typical value is about 0.5%,[14] so a rather unlikely 5 kg of the extremely sour leaves would have to be consumed to reach an LD50 dose of oxalic acid. Cooking the leaves with soda can make them more poisonous by producing soluble oxalates.[15] However, the leaves are believed to also contain an additional, unidentified toxin,[16] which might be an anthraquinone glycoside (also known as senna glycosides).[17]

In the petioles, the amount of oxalic acid is much lower, only about 2-2.5% of the total acidity.[18]

References

  1. ^ a b Rombauer, Irma S. Joy of Cooking Indianapolis/New York:1975 Bobbs-Merrill Co., Inc. Page 142
  2. ^ "Rhubarb Varieties". Rhubarbinfo.com. 2004-09-01. http://www.rhubarbinfo.com/rhubarb-varieties.html. Retrieved 2010-03-05. 
  3. ^ a b John Uri Lloyd (1921), Origin and History of All the Pharmacopeial Vegetable Drugs, Chemicals and Origin and History of All the Pharmacopeial Vegetable Drugs, Chemicals and Preparations with Bibliography, 1, http://books.google.com/books?id=apAPal8iAxgC&pg=PA270 
  4. ^ McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York, NY: Scribner, 2004. p. 366
  5. ^ Waters, Alice. Chez Panisse Fruit. New York, NY: Harper Collins, 2002. p 278
  6. ^ Wakefield Metropolitan District Council. "Rhubarb". http://www.wakefield.gov.uk/CultureAndLeisure/HistoricWakefield/Rhubarb/default.htm. Retrieved 2006-03-12. 
  7. ^ McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York, NY: Scribner, 2004. p 367
  8. ^ Foster, Steven & Yue, Chongxi (1992), Herbal emissaries: bringing Chinese herbs to the West : a guide to gardening, herbal wisdom, and well-being, Rochester, VT: Healing Arts Press, p. 135, ISBN 0892813490, http://books.google.com/books?id=y78zzxTN570C&pg=PA135, retrieved 2009-07-11 
  9. ^ Mrs M Grieve. "botanical.com - A Modern Herbal". http://www.botanical.com/botanical/mgmh/r/rhubar14.html. Retrieved 2009-07-07. 
  10. ^ Charles Perry, trans. An Anonymous Andalusian Cookbook of the 13th Century
  11. ^ Oxford English Dictionary s.n. rhubarb, n.
  12. ^ http://www.ncbi.nlm.nih.gov/pubmed/19235684 "Rhaponticin from rhubarb rhizomes alleviates liver steatosis and improves blood glucose and lipid profiles in KK/Ay diabetic mice." 2009
  13. ^ "Rhurbarb poisoning on rhurbabinfo.com". http://www.rhubarbinfo.com/rhubarb-poison.html. 
  14. ^ GW Pucher, AJ Wakeman, HB Vickery. THE ORGANIC ACIDS OF RHUBARB (RHEUM HYBRIDUM). III. THE BEHAVIOR OF THE ORGANIC ACIDS DURING CULTURE OF EXCISED LEAVES. Journal of Biological Chemistry, 1938
  15. ^ Everist, Selwyn L., Poisonous Plants of Australia. Angus and Robertson, Melbourne, 1974, p. 583
  16. ^ "Rhubarb leaves poisoning". Medline Plus Medical Encyclopedia. http://www.nlm.nih.gov/medlineplus/ency/article/002876.htm. 
  17. ^ "Canadian Poisonous Plants Information System". Cbif.gc.ca. 2009-09-01. http://www.cbif.gc.ca/pls/pp/ppack.info?p_psn=171&p_type=all&p_sci=sci. Retrieved 2010-03-05. 
  18. ^ McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York, NY: Scribner, 2004. p. 367

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

RHUBARB. This name is applied both to a drug and to a vegetable.

1. The drug has been used in medicine from very early times, being described in the Chinese herbal Pen-king, which is believed to date from 2700 B.C. The name seems to be a corruption of Rheum barbarum or Reu barbarum, a designation applied,to the drug as early as the middle of the 6th century, and apparently identical with the prloP or pc of Dioscorides, described by him as a root brought from beyond the Bosporus. In the 14th century rhubarb appears to have found its way to Europe by way of the Indus and Persian Gulf to the Red Sea and Alexandria, and was therefore described as "East Indian" rhubarb. Some also came by way of Persia and the Caspian to Syria and Asia Minor, and reached Europe from the ports of Aleppo and Smyrna, and became known as "Turkey" rhubarb. Subsequently to the year 1653, when China first permitted Russia to trade on her frontiers, Chinese rhubarb reached Europe chiefly by way of Moscow; and in 1704 the rhubarb trade became a monopoly of the Russian government, in consequence of which the term "Russian" or "crown" rhubarb came to be applied to it. Urga was the great depot for the rhubarb trade in 171 9, but in 1728 the depot was transferred to Kiachta. All rhubarb brought to the depot passed through the hands of the government inspector; hence Russian rhubarb was invariably good and obtained a remarkably high price. This severe supervision naturally led, as soon as the northern Chinese ports were thrown open to European trade, to a new outlet being sought; and the increased demand for the drug at these ports resulted in less care being exercised by the Chinese in the collection and curing of the root, so that the rhubarb of good quality offered at Kiachta rapidly dwindled in quantity, and after 1860 Russian rhubarb ceased to appear in European commerce. Owing to the expense of carrying the drug across the whole breadth of Asia, and the difficulty of preserving it from the attacks of insects, rhubarb was formerly one of the most costly of drugs. In 1542 it was sold in France for ten times the price of cinnamon and four times that of saffron, and in an English price list bearing date of 1657 it is quoted at. 16s. per lb, opium being at that time only 6s. and scammony 12s.

per lb.

The dose of rhubarb is anything from 2 up to 30 grains, according to the action which is desired. The British Pharmacopeia contains seven preparations, only one of which is of any special value. This is the Pulvis Rhei Compositus, or Gregory's powder, which is composed of 2 parts of rhubarb, 6 of heavy or light magnesia and 1 of ginger. The dose is 20 to 60 gr.

Rhubarb is used in small doses-2 to 2 gr. - as an astringent tonic, since it stimulates all the functions of the upper part of the alimentary canal. In many cases of torpid dyspepsia it is very efficient when combined with the subnitrate of bismuth and the bicarbonate of sodium. The more characteristic action of rhubarb, however, is purgation, which it causes in doses of 15 gr. and upwards. The action occurs within seven or eight hours, a soft, pulpy motion of a yellow colour being produced. The colour is due to the chrysarobin, which is also the purgative constituent of the drug. Rhubarb is also a secretory cholagogue, increasing the amount of bile formed by the liver. The drug is apt to cause colic, and should therefore never be given alone. The ginger in Gregory's powder averts this unpleasant consequence of the aperient properties of rhubarb. The drug is peculiar in that the purgation is succeeded by definite constipation, said to be due to the rheotannic acid. This explanation is hardly satisfactory, however, since it is difficult to see how the rheotannic acid can be retained in the bowel during the process of purgation. Rhubarb has, therefore, definite indications and contra-indications. It is obviously worse than useless in the treatment of chronic constipation, which it only aggravates. On the other hand, it is very valuable in children and others, when diarrhoea has been caused by an unsuitable dietary. The drug removes the indigestible residue of the food and then gives the bowel rest. Rhubarb is also useful in the weaning of infants, since it is partly excreted in the maternal milk, and gives it a bitter taste which the baby dislikes.

Some chrysarobin is absorbed and is excreted in the urine, which it slightly increases and colours a reddish brown. The colour ie discharged by the addition of a little dilute hydrochloric acid to the urine.

The botanical source of Chinese rhubarb cannot be said to have been as yet definitely cleared up by actual identification of plants observed to be used for the purpose. Rheum palmatum, R. officinale, R. palmatum, var. tanguticum, R. colinianum and R. Franzenbachii have been variously stated to be the source of it, but the roots produced by these species under cultivation in Europe do not present the characteristic network of white veins exhibited by the best specimens of the Chinese drug.

Chemistry

The most important constituent of this drug, giving it its purgative properties and its yellow colour, is chrysarobin, C30H3607, formerly known as rhein or chrysophan. The rhubarb of commerce also contains chrysophanic acid, a dioxymethyl anthraquinone, C 14 H 5 (CH 3)O 2 (OH)2, of which chrysarobin is a reduction product. Nearly 40% of the drug consists of calcium oxalate, which gives it the characteristic grittiness. There is also present rheotannic acid, which is of some practical importance. There are numerous other constituents, such as emodin, C15H1005, mucilage, resins, rheumic acid, C20H1609f aporrhetin, &c.

Production and Commerce. - Rhubarb is produced in the four northern provinces of China proper (Chih-li, Shan-se, Shen-se and Ho-nan), in the north-west provinces of Kan-suh, formerly included in Shen-se, but now extending across the desert of Gobi to the frontier of Tibet, in the Mongolian province of Tsing-hai, including the salt lake Koko-nor, and the districts of Tangut, Sifan and Turfan, and in the mountains of the western provinces of Sze-chuen.1 Two of the most important centres of the trade are Sining-fu in the province of Kan-suh, and Kwanhien in Sze-chuen. From Shen-se, Kan-suh and Sze-chuen the rhubarb is forwarded to Hankow, and thence carried to Shanghai, whence it is shipped to Europe. Lesser quantities are shipped from Tien-tsin, and occasionally the drug is exported from Canton, Amoy, Fuh-chow and Ning-po.

Very little is known concerning the mode of preparing the drug for the market. According to Mr Bell, who on a journey from St Petersburg to Peking had the opportunity of observing the plant in a growing state, the root is not considered to be mature until it is six years old. It is then dug up, usually in the autumn, and deprived of its cortical portion and smaller branches, and the larger pieces are divided in half longitudinally; these pieces are bored with holes and strung up on cords to dry, in some cases being previously subjected to a preliminary drying on stone slabs heated by fire underneath. In Bhutan the root is said to be hung up in a kind of drying room. in which a moderate heat is regularly maintained. The effect produced by the two drying processes is very different: when dried by artificial heat, the exterior of the pieces becomes hardened before the interior has entirely lost its moisture, and consequently the pieces decay in the centre, although the surface may show no change. These two varieties are technically known as kiln-dried and sun-dried; and it was on account of this difference in quality that the Russian officer at Kiachta had every piece examined by boring a hole to its centre.

European Rhubarb

As early as 1608 Prosper Alpinus of Padua cultivated as the true rhubarb a plant which is now known as Rheum rhaponticum, a native of southern Siberia and the basin of the Volga. This plant was introduced into England through Sir Matthew Lister, physician to Charles I., who gave seed obtained by him in Italy to the botanist Parkinson. The culture of this rhubarb for the sake of the root was commenced in 1777 at Banbury, in Oxfordshire, by an apothecary named Hayward, the plants being raised from seed sent from Russia in 1762, and with such success that the Society of Arts awarded hint a silver medal in 1789 and a gold one in 1794. The cultivation subsequently extended to Somersetshire, Yorkshire, and Middlesex, but is now chiefly carried on at Banbury. English rhubarb root is sold at a cheaper rate than the Chinese rhubarb, and forms a considerable article of export to America, and is said to be used in Britain in the form of powder, which is of a finer°yellow colour than that of Chinese rhubarb. The Banbury rhubarb appears to be a hybrid between R. rhaponticum and R. undulatum - the root, according to E. Cohn, not presenting the typical microscopic structure of the former. More recently very 1 According to Mr F. Newcombe, 'Med,' Press and Circ., August 2, 1882, the Chinese esteem the Shen-se rhubarb as the best, that coming from Kanchow being the most prized of all; Sze-chuen rhubarb has a rougher surface and little flavour, and brings only about half the price; Chung-chi rhubarb also is greatly valued, while the Chi-chuang, Tai-huang and Shan-huang varieties are considered worthless.

good rhubarb has been grown at Banbury from Rheum officinale, but these two varieties are not equal in medicinal strength to the Chinese article, yielding less extract - Chinese rhubarb affording, according to H. Seier, 58%, English rhubarb 21 io and R. officinale 17%. In France the cultivation of rhubarb was commenced in the latter half of the 18th century - R. compactum, R. palmatum, R. rhaponticum and R. undulatum being the species grown. The cultivation has, however, now nearly ceased, small quantities only being prepared at Avignon and a few other localities.

The culture of Rheum compactum was begun in Moravia in the beginning of the present century by Prikyl, an apothecary in Austerlitz, and until about fifty years ago the root was largely exported to Lyons and Milan, where it was used for dyeing silk. As a medicine 5 parts are stated to be equal to 4 of Chinese rhubarb. Rhubarb root is also grown at Auspitz in Moravia and at Ilmitz, Kremnitz and Frauenkirchen in Hungary; R. emodi is said to be cultivated for the same purpose in Silesia.

Rhubarb is also prepared for use in medicine from wild species in the Himalayas and Java.

2. The rhubarb used as a vegetable consists of the leaf stalks of R. rhaponticum and its varieties, and R. undulatum. It is known in America as pie-plant. Plants are readily raised from seed, but strong plants can be obtained in a much shorter time by dividing the roots. Divisions or seedlings are planted about 3 ft. apart in ground which has been deeply trenched and manured, the crowns being kept slightly above the surface. Rhubarb grows freely under fruit-trees, but succeeds best in an open situation in rich, rather light soil. The stalks should not be pulled during the first season. If a top-dressing of manure be given each winter a plantation will last good for several years. Forced rhubarb is much esteemed in winter and early spring, and forms a remunerative crop. Forcing under glass or in a mushroom house is most satisfactory, but open-ground forcing may be effected by placing pots or boxes over the roots and burying in a good depth of stable litter and leaves. Several other species, such as R. palmatuin, R. officinale, R. nobile and others, are cultivated for their fine foliage and handsome inflorescence, especially in wild gardens, margins of shrubberies and similar places. They succeed in most soils, but prefer a rich soil of good depth. They are propagated by seeds or by division.


<< Rho Xolani

Rhyl >>


Simple English

Rhubarb
File:Rheum rhabarbarum.2006-04-27.
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Caryophyllales
Family: Polygonaceae
Genus: Rheum
L.

Rhubarb is a kind of plant. It is known for its color. It is baked in pie sometimes. It tastes good with sugar. The leaves are no good.


Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message