Product Code Database
Rhubarb is the fleshy, edible stalks (petioles) of species and hybrids (culinary rhubarb) of Rheum in the family Polygonaceae, which are cooked and used for food. The plant is a herbaceous perennial plant that grows from short, thick . Historically, different plants have been called "rhubarb" in English. The large, triangular leaf contain high levels of oxalic acid and anthrone , making them inedible. The small are grouped in large compound leafy greenish-white to rose-red .
The precise origin of culinary rhubarb is unknown. The species Rheum rhabarbarum (syn. R. undulatum) and R. rhaponticum were grown in Europe before the 18th century and used for medicinal purposes. By the early 18th century, these two species and a possible hybrid of unknown origin, R. × hybridum, were grown as vegetable crops in England and Scandinavia. They readily hybridize, and culinary rhubarb was developed by selecting open-pollinated seed, so its precise origin is almost impossible to determine. In appearance, samples of culinary rhubarb vary on a continuum between R. rhaponticum and R. rhabarbarum. However, modern rhubarb cultivars are with 2 n = 44, in contrast to 2 n = 22 for the wild species.
Rhubarb is a vegetable and is often put to the same culinary uses as .Karen Jean Matsko Hood (2014). 9781930948006, Whispering Pine Press International. . ISBN 9781930948006 The leaf stalks can be used raw while they have a crisp texture, but are most commonly cooked with sugar and used in , , and other . They have a strong, tart taste. Many have been developed for human consumption, most of which are recognised as Rheum × hybridum by the Royal Horticultural Society.
In the United Kingdom, the first rhubarb of the year is harvested by candlelight in Rhubarb forcer where all other light is excluded, a practice that produces a sweeter, more tender stalk.McGee, Harold (2004). On Food and Cooking. New York, NY: Scribner. p 367. These sheds are dotted around the "Rhubarb Triangle" in Yorkshire between Wakefield, Leeds, and Morley.
In the United States rhubarb is primarily produced in the states of Oregon, Washington, and Wisconsin with approximately 1,200 acres in production, of which 175 are covered in hothouses. In the northwestern US states of Oregon and Washington, there are typically two harvests, from late April to May and from late June into July; half of all US commercial production is in Pierce County, Washington. Rhubarb is ready to consume as soon as harvested, and freshly cut stalks are firm and glossy.
Rhubarb damaged by severe cold should not be eaten, as it may be high in oxalic acid, which migrates from the leaves and can cause illness.
The colour of 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 , and varies according to both rhubarb variety and production technique. The colour is not related to its suitability for cooking.
The cost of transportation across Asia made rhubarb expensive in medieval Europe. It was several times the price of other valuable herbs and spices such as cinnamon, opium, and saffron. The merchant explorer Marco Polo therefore searched for the place where the plant was grown and harvested, discovering that it was cultivated in the mountains of Tangut people province. The value of rhubarb can be seen in Ruy Gonzáles de Clavijo's report of his embassy in 1403–1405 to Timur in Samarkand: "The best of all merchandise coming to Samarkand was from China: especially silks, satins, musk, ruby, , , and rhubarb...."Quoted in
The high price, as well as the increasing demand from apothecaries, stimulated efforts to cultivate the different species of rhubarb on European soil. R. rhaponticum × R. officinale came to be grown in England to produce the roots. R. alpinus was also allowed to grow wild. The local availability of the plants grown for medicinal purposes, together with the increasing abundance and decreasing price of sugar in the 18th century, galvanised its culinary adoption. Grieve claims a date of 1820 in England. Rhubarb was harvested in Scotland from at least 1786, having been introduced to the Botanical Garden in Edinburgh by the traveller Bruce of Kinnaird in 1774. He brought the seeds from Abyssinia and they produced 3,000 plants.Grants Old and New Edinburgh
Though it is often asserted that rhubarb first came to the United States in the 1820s,Waters, Alice (2002) Chez Panisse Fruit. New York: Harper Collins. p. 278. John Bartram was growing medicinal and culinary rhubarbs in Philadelphia from the 1730s, planting seeds sent to him by Peter Collinson. From the first, the familiar garden rhubarb was not the only Rheum in American gardens: Thomas Jefferson planted Rheum undulatum at Monticello in 1809 and 1811, observing that it was "Esculent rhubarb, the leaves excellent as Spinach."
Commonly, it is stewed with sugar or used in pies and desserts, but it can also be put into savoury dishes or pickled. Rhubarb can be dehydrated and infused with fruit juice. In the United States, it is usually infused with strawberry juice to mimic the popular strawberry rhubarb pie.
In Northern Europe and North America, the stalks are commonly cut into pieces and stewed with added sugar until soft. The resulting compote, sometimes thickened with corn starch, can then be used in pies, tarts and crumbles. Alternatively, greater quantities of sugar can be added with pectin to make Fruit preserves. A paired spice used is ginger, although cinnamon and nutmeg are also common additions.
In the United Kingdom, as well as being used in the typical pies, tarts and crumbles, rhubarb compote is also combined with whipped cream or custard to make rhubarb Fruit fool. In the United States, the common usage of rhubarb in pies has led to it being nicknamed "pie plant", by which it is referred to in 19th-century cookbooks.
Rhubarb can also be used to make alcoholic drinks, such as or Finnish rhubarb sima (mead). It is also used to make Kompot.
The rhizomes contain stilbenoid compounds (including rhaponticin), and the flavanol (+)-catechin-5- O-glucoside and (−)-catechin-7- O-glucoside.
The (median lethal dose) for pure oxalic acid in rats is about 375 mg/kg body weight, or about 25 grams for a human. Other sources give a much higher oral LDLo (lowest published lethal dose) of 600 mg/kg. While the oxalic acid content of rhubarb leaves can vary, a typical value is about 0.5%, meaning a 65 kg adult would need to eat 4 to 8 kg (9 to 18 lbs) to obtain a lethal dose, depending on which lethal dose is assumed. Cooking the leaves with baking soda can make them more poisonous by producing soluble .Everist, Selwyn L. (1974), Poisonous Plants of Australia. Angus and Robertson, Melbourne. p. 583. The leaves are believed to also contain an additional, unidentified toxin, which might be an anthraquinone glycoside (also known as ).
In the petioles (leaf stalks), the proportion of oxalic acid is about 10% of the total 2–2.5% acidity, which derives mainly from malic acid. Serious cases of rhubarb poisoning are not well documented. Both fatal and non-fatal cases of rhubarb poisoning may be caused not by oxalates, but rather by toxic anthraquinone glycosides.
Hungry wildlife may dig up and eat rhubarb roots in the spring, as stored starches are turned to sugars for new foliage growth.
Cultivars
The advocate of organic gardening Lawrence D. Hills listed his favourite rhubarb varieties for flavour as 'Hawke's Champagne', 'Victoria', 'Timperley Early', and 'Early Albert', also recommending 'Gaskin's Perpetual' for having the lowest level of oxalic acid, allowing it to be harvested over a much longer period of the growing season without developing excessive sourness.Lawrence D Hills. Organic Gardening. Penguin 1997. page 145
The Royal Horticultural Society has the UK's national collection of rhubarb that comprises 103 varieties. In 2021–2022 this was moved from southern England to the more northern garden RHS Bridgewater where winter cold and rainfall are better suited for rhubarb. The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:
Uses
Rhubarb is grown primarily for its fleshy leafstalks, technically known as petioles. The use of rhubarb stalks as food is a relatively recent innovation. This usage was first recorded in 18th- to 19th-century England after affordable sugar became more widely available.
Food
The species Rheum ribes has been eaten in the Islamic world since the 10th century.
Neal, Bill (2025). 9780807854747, Chapel Hill, NC: University of North Carolina Press. ISBN 9780807854747 Rhubarb in the US is also often paired with strawberries to make strawberry-rhubarb pie, though some rhubarb purists jokingly consider this "a rather unhappy marriage".
Nutrition
Raw rhubarb is 94% water, 5% , 1% protein, and contains negligible fat (table). In a reference amount, raw rhubarb supplies of food energy, and is a rich source of vitamin K (28% of the Daily Value, DV), a moderate source of vitamin C (10% DV), and contains no other in significant amounts (table).
Traditional Chinese medicine
In traditional Chinese medicine, rhubarb roots of several species were used as a laxative for several millennia, although there is no clinical evidence to indicate such use is effective.
Phytochemistry and potential toxicity
The roots and stems contain anthraquinones, such as emodin and rhein. Emodin "represents a Genotoxicity risk for humans" while rhein is "a compound devoid of genotoxic capabilities". The anthraquinones have been separated from powdered rhubarb root for purposes in traditional medicine, although long-term consumption of anthraquinones has been associated with acute kidney failure.
Oxalic acid
Rhubarb leaves contain substances, including oxalic acid, a nephrotoxin. The long term consumption of oxalic acid leads to kidney stone formation in humans. Humans have been poisoned after ingesting the leaves, a particular problem during World War I when the leaves were mistakenly recommended as a food source in Britain.Cooper, M. R., Johnson, A. W. (1984). Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. The toxic rhubarb leaves have been used in flavouring extracts, after the oxalic acid is removed by treatment with precipitated chalk (i.e., calcium carbonate).
Pests
Rhubarb is a host to the rhubarb curculio, Lixus concavus, which is a weevil. Damage is mainly visible on leaves and stalks, with gummosis and oval or circular feeding and egg-laying sites.
Cookbook
==Gallery== jar for rhubarb]]
Further reading
External links
|
|
