On Food And Cooking Part 38

Potatoes are prepared in many ways, and used as an ingredient in many dishes. Here are brief notes on a few starring roles.

Mashed and Pureed Potatoes There are many different styles of mashed potatoes, but all of them involve cooking the potatoes whole or in pieces, crus.h.i.+ng them to a more or less fine particle size, and lubricating and enriching the particles with a combination of water and fat, usually in the form of b.u.t.ter and milk or cream. Some luxurious versions may be almost as much b.u.t.ter as potato, or include eggs or egg yolks. Mealy types fall apart into individual cells and small aggregates, so they offer a large surface area for coating by the added ingredients, and readily produce a fine, creamy consistency. Waxy potatoes require more mas.h.i.+ng to obtain a smooth texture, exude more gelated starch, and don't absorb enrichment as easily. The cla.s.sic French There are many different styles of mashed potatoes, but all of them involve cooking the potatoes whole or in pieces, crus.h.i.+ng them to a more or less fine particle size, and lubricating and enriching the particles with a combination of water and fat, usually in the form of b.u.t.ter and milk or cream. Some luxurious versions may be almost as much b.u.t.ter as potato, or include eggs or egg yolks. Mealy types fall apart into individual cells and small aggregates, so they offer a large surface area for coating by the added ingredients, and readily produce a fine, creamy consistency. Waxy potatoes require more mas.h.i.+ng to obtain a smooth texture, exude more gelated starch, and don't absorb enrichment as easily. The cla.s.sic French pommes purees, pommes purees, pureed potatoes, are made from waxy potatoes, pieces of which are pushed through a fine sieve or food mill and then worked hard - to the point of having what an eminent French cookbook writer, Mme Ste-Ange, called a "dead arm" - first alone and then with b.u.t.ter, to incorporate air and obtain the lightness of whipped cream. American recipes take a more gentle approach, sieving mealy varieties and carefully stirring in liquid and fat to avoid excessive cell damage, starch release, and glueyness. pureed potatoes, are made from waxy potatoes, pieces of which are pushed through a fine sieve or food mill and then worked hard - to the point of having what an eminent French cookbook writer, Mme Ste-Ange, called a "dead arm" - first alone and then with b.u.t.ter, to incorporate air and obtain the lightness of whipped cream. American recipes take a more gentle approach, sieving mealy varieties and carefully stirring in liquid and fat to avoid excessive cell damage, starch release, and glueyness.

Fried Potatoes Fried potatoes are some of the world's favorite foods. Deep-fried potato sticks and slices and the technique of double-frying were all well known in Europe by the middle of the 19th century, and in England were attributed mainly to the French: hence the term "French fry" for what the French simply call fried potatoes ( Fried potatoes are some of the world's favorite foods. Deep-fried potato sticks and slices and the technique of double-frying were all well known in Europe by the middle of the 19th century, and in England were attributed mainly to the French: hence the term "French fry" for what the French simply call fried potatoes (pommes frites). These products happily turned out to be among the few foods whose quality need not be compromised by ma.s.s production. Of course they're rich: the frying oil in which they're immersed coats their surface and is drawn into the tiny pores created when the surfac dries out. The proportion of oil to potato depends on the surface area. Chips, which are almost all surface, average about 35% oil, while thick fries are more like 1015%.

French Fries "French fries" may first have been made in significant quant.i.ties by Parisian street vendors early in the 19th century. They are potato sticks cut with a square cross section, 510 mm on a side, deep-fried in oil, with a crisp gold exterior and a moist interior that's fluffy if the potatoes are high-starch russets, creamy otherwise. Simple quick frying doesn't work very well; it gives a thin, delicate crust that's quickly softened by the interior's moisture. A crisp crust requires an initial period of gentle frying, so that starch in the surface cells has time to dissolve from the granules and reinforce and glue together the outer cell walls into a thicker, more robust layer. Good fries can be made by starting the potato strips in relatively cool oil, 250325F/120163C, cooking for 810 minutes, then raising the oil temperature to 350375F/175190C and cooking for 34 minutes to brown and crisp the outside. The most efficient production method is to pre-fry all the potato strips at the lower temperature ahead of time, set them aside at room temperature, and then do the brief high-temperature frying at the last minute. "French fries" may first have been made in significant quant.i.ties by Parisian street vendors early in the 19th century. They are potato sticks cut with a square cross section, 510 mm on a side, deep-fried in oil, with a crisp gold exterior and a moist interior that's fluffy if the potatoes are high-starch russets, creamy otherwise. Simple quick frying doesn't work very well; it gives a thin, delicate crust that's quickly softened by the interior's moisture. A crisp crust requires an initial period of gentle frying, so that starch in the surface cells has time to dissolve from the granules and reinforce and glue together the outer cell walls into a thicker, more robust layer. Good fries can be made by starting the potato strips in relatively cool oil, 250325F/120163C, cooking for 810 minutes, then raising the oil temperature to 350375F/175190C and cooking for 34 minutes to brown and crisp the outside. The most efficient production method is to pre-fry all the potato strips at the lower temperature ahead of time, set them aside at room temperature, and then do the brief high-temperature frying at the last minute.

Potato Chips Potato chips are essentially french fries that are all crust and no interior. The potatoes are cut into thin cross sections around 1.5 mm thick, the equivalent of just 1012 potato cells, then deep-fried until dry and crisp. There are two basic ways of frying chips, and they produce two different textures. Cooking at a fairly constant and high oil temperature, around 350F/175C, heats the slices so rapidly that the starch granules and cell walls have little chance to absorb any moisture before they're desiccated and done, in 34 minutes. The texture is therefore delicately crisp and fine-grained. Most packaged chips have this texture because they're made in a continuous processor whose oil temperature stays high. On the other hand, cooking at an initially low and slowly increasing temperature, beginning around 250F/120C and reaching 350F/175C in 810 minutes, gives the starch granules time to absorb water, exude dissolved starch into the potato cell walls, and reinforce and glue them together. The result is a much harder, crunchier chip. This is the texture created by "kettle frying," or cooking the slices by the batch in a vessel like an ordinary pot. The temperature of the preheated kettle drops immediately when a batch of cold potatoes is dumped in, so the potatoes cook in oil whose temperature starts low and rises slowly as the potatoes' moisture is cooked out and the heater catches up. Potato chips are essentially french fries that are all crust and no interior. The potatoes are cut into thin cross sections around 1.5 mm thick, the equivalent of just 1012 potato cells, then deep-fried until dry and crisp. There are two basic ways of frying chips, and they produce two different textures. Cooking at a fairly constant and high oil temperature, around 350F/175C, heats the slices so rapidly that the starch granules and cell walls have little chance to absorb any moisture before they're desiccated and done, in 34 minutes. The texture is therefore delicately crisp and fine-grained. Most packaged chips have this texture because they're made in a continuous processor whose oil temperature stays high. On the other hand, cooking at an initially low and slowly increasing temperature, beginning around 250F/120C and reaching 350F/175C in 810 minutes, gives the starch granules time to absorb water, exude dissolved starch into the potato cell walls, and reinforce and glue them together. The result is a much harder, crunchier chip. This is the texture created by "kettle frying," or cooking the slices by the batch in a vessel like an ordinary pot. The temperature of the preheated kettle drops immediately when a batch of cold potatoes is dumped in, so the potatoes cook in oil whose temperature starts low and rises slowly as the potatoes' moisture is cooked out and the heater catches up.

Soufflee Potatoes Soufflee potatoes are a kind of hybrid French fry-chip in which the potato slices puff up into delicate brown balloons. They are made by cutting potato slices around 3 mm ( Soufflee potatoes are a kind of hybrid French fry-chip in which the potato slices puff up into delicate brown balloons. They are made by cutting potato slices around 3 mm (1/8 in) thick, and deep-frying them at a moderate temperature, 350F/175C, until their surfaces become leathery and just begin to brown. The slices are cooled, then fried a second time at a high temperature, around 380F/195C. Now when the interior moisture is heated to the boil and vaporized, the stiffened surfaces resist the pressure, and the vapor pushes the two surfaces apart, leaving a hollow center. in) thick, and deep-frying them at a moderate temperature, 350F/175C, until their surfaces become leathery and just begin to brown. The slices are cooled, then fried a second time at a high temperature, around 380F/195C. Now when the interior moisture is heated to the boil and vaporized, the stiffened surfaces resist the pressure, and the vapor pushes the two surfaces apart, leaving a hollow center.

Sweet Potatoes The sweet potato is the true storage root of Ipomoea batatas, Ipomoea batatas, a member of the morning glory family. It is native to northern South America, and may have reached Polynesia in prehistoric times. Columbus brought the sweet potato to Europe, and by the end of the 15th century it was established in China and the Philippines. China now produces and consumes far more sweet potatoes than the Americas, enough to make it the second most important vegetable worldwide. There are many different varieties, ranging from dry and starchy varieties common in tropical regions, some pale and others red or purple with anthocyanins, to the moist, sweet version, dark orange with beta-carotene, that is popular in the United States and was confusingly named a "yam" in 1930s marketing campaigns (for true yams, see p. 306). The bulk of the U.S. crop is grown in the Southeast and cured for several days at 86F/30C to heal damaged skin and encourage sugar development. True to their subtropical heritage, sweet potatoes store best at 5560F/ 1316C. Chilling injury can contribute to "hardcore," a condition in which the root center remains hard even when cooked. a member of the morning glory family. It is native to northern South America, and may have reached Polynesia in prehistoric times. Columbus brought the sweet potato to Europe, and by the end of the 15th century it was established in China and the Philippines. China now produces and consumes far more sweet potatoes than the Americas, enough to make it the second most important vegetable worldwide. There are many different varieties, ranging from dry and starchy varieties common in tropical regions, some pale and others red or purple with anthocyanins, to the moist, sweet version, dark orange with beta-carotene, that is popular in the United States and was confusingly named a "yam" in 1930s marketing campaigns (for true yams, see p. 306). The bulk of the U.S. crop is grown in the Southeast and cured for several days at 86F/30C to heal damaged skin and encourage sugar development. True to their subtropical heritage, sweet potatoes store best at 5560F/ 1316C. Chilling injury can contribute to "hardcore," a condition in which the root center remains hard even when cooked.

Most sweet potato varieties sweeten during cooking thanks to the action of an enzyme that attacks starch and breaks it down to maltose, a sugar made up of two glucose molecules that's about a third as sweet as table sugar. Moist or "soggy" varieties convert as much as 75% of their starch to maltose, so they seem permeated with syrup! The enzyme starts to make maltose when the tightly packed starch granules absorb moisture and expand, beginning around 135F/57C, and it stops when the rising heat denatures it, at around 170F/75C. Slow baking therefore gives the enzyme a longer time to work than does rapid cooking in steam, boiling water, or a microwave, and produces a sweeter result. Freshly harvested "green" roots available in the autumn have less enzyme activity and so don't become as sweet or moist.

Pale and red-purple sweet potatoes have a delicate, nutty aroma, while orange types have the heavier, pumpkin-like quality created by fragments of the carotenoid pigments. Some varieties (e.g., red-skinned Garnet) suffer from after-cooking darkening (p. 303) due to their abundant phenolic compounds.

Tropical Roots and Tubers Root and tuber vegetables that come from the tropics generally contain less water than common potatoes, and as much as double the starch (potatoes are 18% carbohydrate by weight, ca.s.savas 36%). They therefore become very floury when baked, dense and waxy when boiled or steamed, and help thicken soups and stews in which they're included. They have a relatively short storage life and suffer chilling damage if refrigerated, but can be frozen after preliminary peeling and cutting.

Ca.s.sava, Manioc, and Yuca These are all names for the elongated root of a tropical plant in the spurge family, These are all names for the elongated root of a tropical plant in the spurge family, Manihot esculenta, Manihot esculenta, which has the very useful habit of lasting in the ground for as much as three years. It was domesticated in northern South America, and has spread through the lowland tropics of Africa and Asia in the last century or so. It's often made into flatbreads or fermented as well as cooked on its own. There are two general groups of ca.s.sava varieties: potentially toxic "bitter" varieties that are used in the producing countries, and safer "sweet" varieties that are exported and found in our ethnic markets. Bitter varieties, which are highly productive crop plants, have defensive cells that generate bitter cyanide throughout the root, and must be thoroughly treated - for example, by shredding, pressing, and was.h.i.+ng - to become safe and palatable. They're mainly processed in the producing countries into flour and tapioca, small b.a.l.l.s of dried ca.s.sava starch that become pleasantly jelly-like when remoistened in desserts and drinks. Sweet ca.s.sava varieties are less productive crop plants, but have cyanide defenses only near their surface, and are safe to eat after peeling and normal cooking. The root flesh is snow-white and dense, with a bark-like skin and a fibrous core usually removed before cooking. Ca.s.sava benefits from cooking in water to moisten the starch before being fried or baked. which has the very useful habit of lasting in the ground for as much as three years. It was domesticated in northern South America, and has spread through the lowland tropics of Africa and Asia in the last century or so. It's often made into flatbreads or fermented as well as cooked on its own. There are two general groups of ca.s.sava varieties: potentially toxic "bitter" varieties that are used in the producing countries, and safer "sweet" varieties that are exported and found in our ethnic markets. Bitter varieties, which are highly productive crop plants, have defensive cells that generate bitter cyanide throughout the root, and must be thoroughly treated - for example, by shredding, pressing, and was.h.i.+ng - to become safe and palatable. They're mainly processed in the producing countries into flour and tapioca, small b.a.l.l.s of dried ca.s.sava starch that become pleasantly jelly-like when remoistened in desserts and drinks. Sweet ca.s.sava varieties are less productive crop plants, but have cyanide defenses only near their surface, and are safe to eat after peeling and normal cooking. The root flesh is snow-white and dense, with a bark-like skin and a fibrous core usually removed before cooking. Ca.s.sava benefits from cooking in water to moisten the starch before being fried or baked.

Food Words: Potato, Yam Potato, YamPotato came into English via the Spanish came into English via the Spanish patata, patata, a version of the word used by the Taino peoples of the Caribbean for the sweet potato, a version of the word used by the Taino peoples of the Caribbean for the sweet potato, batata. batata. The Peruvian Quechua word for the true potato of the Andes was The Peruvian Quechua word for the true potato of the Andes was papa. Yam papa. Yam comes via Portuguese from a West African word meaning "to eat." comes via Portuguese from a West African word meaning "to eat."

Taro and Dasheen Taro and dasheen are two of many names for tubers of a water-loving plant native to eastern Asia and the Pacific islands, Taro and dasheen are two of many names for tubers of a water-loving plant native to eastern Asia and the Pacific islands, Colocasia esculenta, Colocasia esculenta, which is in the arum family (as are calla lilies and philodendrons). Like other arums, taro contains protective crystalline needles of calcium oxalate (40160 mg per 100 gm), and deposits them near stores of protein-digesting enzymes. The result is an a.r.s.enal of something resembling poison-tipped darts: when the tuber is eaten raw, the crystals puncture the skin and then the enzymes eat away at the wound, producing considerable irritation. Cooking overcomes this defensive system by denaturing the enzymes and dissolving the crystals. which is in the arum family (as are calla lilies and philodendrons). Like other arums, taro contains protective crystalline needles of calcium oxalate (40160 mg per 100 gm), and deposits them near stores of protein-digesting enzymes. The result is an a.r.s.enal of something resembling poison-tipped darts: when the tuber is eaten raw, the crystals puncture the skin and then the enzymes eat away at the wound, producing considerable irritation. Cooking overcomes this defensive system by denaturing the enzymes and dissolving the crystals.

Taro is commonly found in two sizes, one the main tuberous growth which may be several pounds, the other smaller side-growths, each a few ounces, and with a moister texture. The flesh is mottled by vessels purplish with phenolic compounds; during cooking the phenolics and color diffuse into and tinge the cream-colored flesh. Taro retains its shape when simmered, and it becomes waxy on cooling. It has a p.r.o.nounced aroma that reminds some of chestnuts, others of egg yolk. In Hawaii taro is boiled, mashed, and fermented into poi, one element in the luau (p. 295).

Taro is sometimes confused with malanga, yautia, and cocoyam, tubers of a number of New World tropical species in the genus Xanthosoma, Xanthosoma, which are also arums protected by oxalate crystals. Malanga grows in drier soils than taro, is more elongated, has an earthier flavor, and more readily falls apart when simmered in soups and stews. which are also arums protected by oxalate crystals. Malanga grows in drier soils than taro, is more elongated, has an earthier flavor, and more readily falls apart when simmered in soups and stews.

Yam True yams are starchy tubers of tropical plants that are related to the gra.s.ses and lilies, a dozen or so cultivated species of True yams are starchy tubers of tropical plants that are related to the gra.s.ses and lilies, a dozen or so cultivated species of Dioscorea Dioscorea from Africa, South America, and the Pacific with varying sizes, textures, colors, and flavors. They are seldom seen in mainstream American markets, where "yam" means a sugary orange sweet potato (p. 304). True yams can grow to 100 lb/50 kg and more, and in the Pacific islands have been honored with their own little houses. They appear to have been cultivated as early as 8000 from Africa, South America, and the Pacific with varying sizes, textures, colors, and flavors. They are seldom seen in mainstream American markets, where "yam" means a sugary orange sweet potato (p. 304). True yams can grow to 100 lb/50 kg and more, and in the Pacific islands have been honored with their own little houses. They appear to have been cultivated as early as 8000 BCE BCE in Asia. Many yams contain oxalate crystals just under the skin, as well as soap-like saponins, which give a slippery, frothy quality to their juices. Some varieties contain a toxic alkaloid called dioscorine that must be removed by grating and leaching in water. Yam tubers help their plants survive drought, and they have a longer pantry life than ca.s.sava or taro. in Asia. Many yams contain oxalate crystals just under the skin, as well as soap-like saponins, which give a slippery, frothy quality to their juices. Some varieties contain a toxic alkaloid called dioscorine that must be removed by grating and leaching in water. Yam tubers help their plants survive drought, and they have a longer pantry life than ca.s.sava or taro.

The Carrot Family: Carrots, Parsnips, and Others Root vegetables in the carrot family share the family habit of containing distinctive aromatic molecules, so they're often used to lend complexity to stocks, stews, soups, and other preparations. Carrots and parsnips contain less starch than potatoes and are notably sweet; they may be 5% sugars, a mixture of sucrose, glucose, and fructose. Carrots have found their way into cakes and sugar preserves in the West, are shredded and sweetened for rice dishes in Iran, and in India are cooked down in milk to make a vegetable kind of fudge (halwa).

Carrot Cultivated carrots are swollen taproots of the species Cultivated carrots are swollen taproots of the species Daucus carota, Daucus carota, which arose in the Mediterranean region. There are two main groups of cultivated carrots. The eastern anthocyanin carrot developed in central Asia, and has reddish-purple to purple-black outer layers and a yellow core of conducting vessels. It's eaten in its home region and can also be found in Spain. The Western carotene carrot appears to be a hybrid among three different groups of ancestors: yellow carrots cultivated in Europe and the Mediterranean since medieval times; white carrots that had been cultivated since cla.s.sical times; and some wild carrot populations. The familiar orange carrot, the richest vegetable source of the vitamin A precursor beta-carotene, appears to have been developed in Holland in the 17th century. There are also Asian carrot varieties whose roots are red with lycopene, the tomato carotenoid. Carotene carrots have the practical advantage of retaining their oil-soluble pigments in water-based dishes, while anthocyanin carrots bleed their water-soluble colors into soups and stews. which arose in the Mediterranean region. There are two main groups of cultivated carrots. The eastern anthocyanin carrot developed in central Asia, and has reddish-purple to purple-black outer layers and a yellow core of conducting vessels. It's eaten in its home region and can also be found in Spain. The Western carotene carrot appears to be a hybrid among three different groups of ancestors: yellow carrots cultivated in Europe and the Mediterranean since medieval times; white carrots that had been cultivated since cla.s.sical times; and some wild carrot populations. The familiar orange carrot, the richest vegetable source of the vitamin A precursor beta-carotene, appears to have been developed in Holland in the 17th century. There are also Asian carrot varieties whose roots are red with lycopene, the tomato carotenoid. Carotene carrots have the practical advantage of retaining their oil-soluble pigments in water-based dishes, while anthocyanin carrots bleed their water-soluble colors into soups and stews.

The distinctive aroma of carrots is due largely to terpenes (p. 273), and is a composite of pine, wood, oil, citrus, and turpentine notes; cooking adds a violet-like note from fragmented carotene. White varieties tend to be the most strongly aromatic. Exposure to sunlight, high temperatures, or physical damage can cause the roots to generate alcohol, which adds to the solvent-like aroma, as well as a bitter defensive chemical. Peeling the thin outer layer removes most of the bitterness as well as phenolic compounds that cause brown discoloration. The sweetness is most noticeable when the roots are cooked, which weakens the strong cell walls and frees the sugars to be tasted. The carrot core carries water from the root to the leaves and has less flavor than the outer storage layers.

Pre-peeled "baby" carrots, actually cut from mature ones, often have a harmless white fuzz on their surface due to damaged outer cell layers that dehydrate within hours of processing.

Parsnip Pastinaca sativa, Pastinaca sativa, along with its aromatic taproot, is native to Eurasia, was known to the Greeks and Romans, and like the turnip was an important staple food before the introduction of the potato. The version known to us today was developed in the Middle Ages. The parsnip acc.u.mulates more starch than the carrot, but converts it to sugars when exposed to cold temperatures; so winter roots are sweeter than autumn roots, and before sugar became cheap were used to make cakes and jams in Britain. Its pale, somewhat dry tissue softens faster during cooking than either the potato's or carrot's. along with its aromatic taproot, is native to Eurasia, was known to the Greeks and Romans, and like the turnip was an important staple food before the introduction of the potato. The version known to us today was developed in the Middle Ages. The parsnip acc.u.mulates more starch than the carrot, but converts it to sugars when exposed to cold temperatures; so winter roots are sweeter than autumn roots, and before sugar became cheap were used to make cakes and jams in Britain. Its pale, somewhat dry tissue softens faster during cooking than either the potato's or carrot's.

Parsley Root Parsley root is the taproot of a particular variety of parsley, Parsley root is the taproot of a particular variety of parsley, Petroselinum crispum Petroselinum crispum var. var. tuberosum, tuberosum, is also flavored by a mixture of terpenoids, and is more complex and pungent than parsley leaves. Parsley is a Eurasian native (p. 408). is also flavored by a mixture of terpenoids, and is more complex and pungent than parsley leaves. Parsley is a Eurasian native (p. 408).

Arracacha Arracacha is the root of a South American member of the carrot family, Arracacha is the root of a South American member of the carrot family, Arracacia xanthorhiza. Arracacia xanthorhiza. It has smooth roots of various colors, and a rich flavor that the eminent plant explorer David Fairchild called much superior to carrots. It has smooth roots of various colors, and a rich flavor that the eminent plant explorer David Fairchild called much superior to carrots.

The Lettuce Family: Sunchoke, Salsify, Scorzonera, Burdock Roots and tubers from northerly members of the lettuce family share three characteristics: an abundance of fructose-based carbohydrates, little starch, and a mild flavor reminiscent of the true artichoke (also a lettuce relative). The fructose carbohydrates (small-chain fructosans and starch-like inulin) provide both an energy store and an antifreeze mechanism for the overwintering plants. Humans don't have the enzymes necessary to digest fructose chains, so beneficial bacteria in our intestines feed on them instead, in the process generating carbon dioxide and other gases that can cause abdominal discomfort if we've eaten a large portion of these vegetables.

The sunchoke is the nonfibrous, plump tuber of a North American sunflower (Helianthus tuberosus), whose traditional and obscure name is "Jerusalem artichoke." It's pleasantly moist, crunchy, and sweet when raw, and becomes soft and sweet after brief cooking. When cooked for 1224 hours at a low temperature, around 200F/93C, sunchoke carbohydrates are largely converted to digestible fructose, and the flesh becomes sweet and translucently brown, like a vegetable aspic.

Salsify (Tragopogon porrifolius), sometimes called "oyster plant" for the supposed flavor resemblance, and black salsify or scorzonera (Scorzonera hispanica (Scorzonera hispanica) are Mediterranean natives. Their Eurasian relative burdock (Arctium lappa) is most appreciated in j.a.pan as gobo. gobo. All three of these elongated taproots become undesirably fibrous with size and age, are rich in phenolic compounds (those in All three of these elongated taproots become undesirably fibrous with size and age, are rich in phenolic compounds (those in gobo gobo are potent antioxidants), and therefore readily turn grayish-brown - at the surface when cut and peeled, throughout when cooked. are potent antioxidants), and therefore readily turn grayish-brown - at the surface when cut and peeled, throughout when cooked.

Other Common Roots and Tubers Chinese Water Chestnut and Tiger Nut The Chinese water chestnut and the tiger nut, or chufa, are both members of the sedge family, a group of water gra.s.ses that includes papyrus. The water chestnut is a swollen underwater stem tip of The Chinese water chestnut and the tiger nut, or chufa, are both members of the sedge family, a group of water gra.s.ses that includes papyrus. The water chestnut is a swollen underwater stem tip of Eleocharis dulcis, Eleocharis dulcis, a native of the Far East cultivated primarily in China and j.a.pan. (Horned water chestnuts or caltrops are the seeds of species of a native of the Far East cultivated primarily in China and j.a.pan. (Horned water chestnuts or caltrops are the seeds of species of Trapa, Trapa, water plants native to Africa, central Europe, and Asia.) Tiger nuts are small tubers of water plants native to Africa, central Europe, and Asia.) Tiger nuts are small tubers of Cyperus esculentus, Cyperus esculentus, a native of northern Africa and the Mediterranean that was cultivated in ancient Egypt. Both taste slightly sweet and nutty, and both are remarkable for retaining their crispness when cooked and even when canned, thanks to phenolic compounds in their cell walls that cross-link and strengthen them. The Spanish make the sweet drink a native of northern Africa and the Mediterranean that was cultivated in ancient Egypt. Both taste slightly sweet and nutty, and both are remarkable for retaining their crispness when cooked and even when canned, thanks to phenolic compounds in their cell walls that cross-link and strengthen them. The Spanish make the sweet drink horchata de chufa horchata de chufa from dried tiger nuts by soaking them in water, grinding and resoaking, straining, and adding sugar. from dried tiger nuts by soaking them in water, grinding and resoaking, straining, and adding sugar.

In Asia, where Chinese and horned water chestnuts are sometimes cultivated in contaminated water, these foods have been known to transmit cysts of a parasitic intestinal fluke to people who sh.e.l.l them with their teeth. Fresh versions should be washed and scrubbed thoroughly before tr.i.m.m.i.n.g away their tough outer layer, then washed again. A brief immersion in boiling water will guarantee their safety.

Crosnes, or Chinese Artichokes Crosnes are small tubers of several species of Crosnes are small tubers of several species of Stachys, Stachys, an Asian member of the mint family; they were brought from China to France in the late 19th century. Crosnes are crisp and taste nutty and sweet, something like a sunchoke. They're notable for containing an unusual carbohydrate, stachyose, a combination of two galactoses and one sucrose. We can't digest stachyose, so a large serving of crosnes can cause ga.s.sy discomfort. Crosnes contain little starch, and turn mushy when even slightly overcooked. an Asian member of the mint family; they were brought from China to France in the late 19th century. Crosnes are crisp and taste nutty and sweet, something like a sunchoke. They're notable for containing an unusual carbohydrate, stachyose, a combination of two galactoses and one sucrose. We can't digest stachyose, so a large serving of crosnes can cause ga.s.sy discomfort. Crosnes contain little starch, and turn mushy when even slightly overcooked.

Jicama Jicama is the swollen storage root of Jicama is the swollen storage root of Pachyrhizus erosus, Pachyrhizus erosus, a South American member of the bean family. Its main virtue is its st.u.r.dy crispness: it keeps well, is slow to discolor, and retains some crunch when cooked. Jicama is often eaten raw, in salads or dipped into a sauce, and is sometimes used as a fresh replacement for Chinese water chestnuts, though it doesn't have the same sweet and nutty character. a South American member of the bean family. Its main virtue is its st.u.r.dy crispness: it keeps well, is slow to discolor, and retains some crunch when cooked. Jicama is often eaten raw, in salads or dipped into a sauce, and is sometimes used as a fresh replacement for Chinese water chestnuts, though it doesn't have the same sweet and nutty character.

Lotus Root Lotus root is the muddwelling rhizome of Lotus root is the muddwelling rhizome of Nelumbo nucifera, Nelumbo nucifera, a water lily native to Asia that has North American and Egyptian relatives. The lily is an important image in Buddhism and other systems of thought - a stalk rising from the mire to bear a beautiful flower over its floating leaves - so lotus root can carry extraculinary connotations. The rhizome contains large void s.p.a.ces, so cross-sectional slices have a characteristic lacy pattern. It is crisp and remains so after cooking, for the same reason that water chestnuts do. It has a mild aroma and slight astringency, and discolors rapidly when cut due to phenolic compounds. Lotus root is cooked in many different ways, after an initial peeling (and blanching in the case of salads), from rapid stir-frying to braising and candying. Its modest store of starch is also extracted. a water lily native to Asia that has North American and Egyptian relatives. The lily is an important image in Buddhism and other systems of thought - a stalk rising from the mire to bear a beautiful flower over its floating leaves - so lotus root can carry extraculinary connotations. The rhizome contains large void s.p.a.ces, so cross-sectional slices have a characteristic lacy pattern. It is crisp and remains so after cooking, for the same reason that water chestnuts do. It has a mild aroma and slight astringency, and discolors rapidly when cut due to phenolic compounds. Lotus root is cooked in many different ways, after an initial peeling (and blanching in the case of salads), from rapid stir-frying to braising and candying. Its modest store of starch is also extracted.

Oca Oca is the small tuber of a South American relative of wood sorrel, Oca is the small tuber of a South American relative of wood sorrel, Oxalis Oxalis tuberosa. tuberosa. It is variably starchy or juicy, comes in a number of anthocyanin-based skin colors, from yellow to red to purple, and is unusual in being distinctly tart, thanks to the oxalic acid typical of the family. In Peru and Bolivia it's usually cooked in stews and soups. It is variably starchy or juicy, comes in a number of anthocyanin-based skin colors, from yellow to red to purple, and is unusual in being distinctly tart, thanks to the oxalic acid typical of the family. In Peru and Bolivia it's usually cooked in stews and soups.

Lower Stems and Bulbs: Beet, Turnip, Radish, Onion, and Others The members of this mixed category of vegetables sit at or just below ground level, and have one characteristic in common: they store little starch compared to most roots and tubers. They're therefore usually less dense, cook more rapidly, and retain a moist texture.

Beets Beet "roots" are mainly the lower stem of Beta vulgaris, Beta vulgaris, a native of the Mediterranean and Western Europe. People have eaten this plant since prehistory, initially its leaves (chard, p. 325), then the underground part of specialized varieties (subspecies a native of the Mediterranean and Western Europe. People have eaten this plant since prehistory, initially its leaves (chard, p. 325), then the underground part of specialized varieties (subspecies vulgaris). vulgaris). In Greek times beet roots were long, either white or red, and sweet; Theophrastus reported around 300 In Greek times beet roots were long, either white or red, and sweet; Theophrastus reported around 300 BCE BCE that they were pleasant enough to eat raw. The fat red type is first depicted in the 16th century. Table beets are about 3% sugar and some large animal-feed varieties are 8%; in the 18th century, selection for sugar production led to sugar beets with 20% sucrose. that they were pleasant enough to eat raw. The fat red type is first depicted in the 16th century. Table beets are about 3% sugar and some large animal-feed varieties are 8%; in the 18th century, selection for sugar production led to sugar beets with 20% sucrose.

Colored beets owe their red, orange, and yellow hues to betain pigments (p. 268), which are water-soluble and stain other ingredients. There are variegated varieties with alternating red layers of phloem tissue and unpigmented layers of xylem (p. 262); they look their best in raw slices because cooking causes cell damage and pigment leakage. When we eat beets, the red pigment is usually decolorized by high stomach acidity and reaction with iron in the large intestine, but people sometimes excrete the intact pigment, a startling but harmless event. The persistent firmness of cooked beets is caused by phenolic reinforcement of the cell walls, as in bamboo shoots and water chestnuts (p. 283).

Beet aroma comes largely from an earthy-smelling molecule called geosmin, which was long thought to originate with soil microbes, but now appears also to be produced by the beet root itself. The sugariness of beets is sometimes put to use in chocolate cakes, syrups, and other sweets.

Celery Root Celery root or celeriac is the swollen lower portion of the main stem of a special variety of celery, Apium graveolens Apium graveolens var. var. rapaceum. rapaceum. Roots project from a k.n.o.bbly surface that requires deep peeling. Celeriac tastes much like celery thanks to the same oxygen-ring aromatics, and contains a moderate amount of starch (56% by weight). It's usually cooked like other root vegetables, but also finely shredded to make a crunchy raw salad. Roots project from a k.n.o.bbly surface that requires deep peeling. Celeriac tastes much like celery thanks to the same oxygen-ring aromatics, and contains a moderate amount of starch (56% by weight). It's usually cooked like other root vegetables, but also finely shredded to make a crunchy raw salad.

The Cabbage Family: Turnip, Radish The turnip, Bra.s.sica rapa, Bra.s.sica rapa, has been under cultivation for about 4,000 years in Eurasia as a staple, fast-growing food. It consists of both lower stem and taproot, can have a number of different shapes and colors, and has the sulfury aroma typical of the family (p. 321). Small, mild varieties may be eaten raw and crunchy like radishes, larger ones cooked until soft: but not too long, or the overcooked cabbage flavor dominates and the texture becomes mushy. Turnips are also pickled. has been under cultivation for about 4,000 years in Eurasia as a staple, fast-growing food. It consists of both lower stem and taproot, can have a number of different shapes and colors, and has the sulfury aroma typical of the family (p. 321). Small, mild varieties may be eaten raw and crunchy like radishes, larger ones cooked until soft: but not too long, or the overcooked cabbage flavor dominates and the texture becomes mushy. Turnips are also pickled.

The crisp, sometimes pungent radish is a different species, Rapha.n.u.s sativus, Rapha.n.u.s sativus, a native of western Asia, and had reached the Mediterranean by the time of the ancient Egyptians and Greeks. Like the turnip it's mainly a swollen lower stem, and has been shaped by human selection into many distinctive forms and striking colors (for example, green at the surface and red inside). Most familiar in the United States are small, early-maturing spring varieties, usually with a bright red skin, which take only a few weeks to grow, and become harsh and woody in summer heat. These are usually eaten raw in salads. But there are also large Spanish and German varieties, some with black skins and some white, that reach several inches in diameter and mature over several months for harvest in the autumn. These types are firm and dry, and take well to braising and roasting. And there are the large, long white Asian radishes, best known by the j.a.panese term a native of western Asia, and had reached the Mediterranean by the time of the ancient Egyptians and Greeks. Like the turnip it's mainly a swollen lower stem, and has been shaped by human selection into many distinctive forms and striking colors (for example, green at the surface and red inside). Most familiar in the United States are small, early-maturing spring varieties, usually with a bright red skin, which take only a few weeks to grow, and become harsh and woody in summer heat. These are usually eaten raw in salads. But there are also large Spanish and German varieties, some with black skins and some white, that reach several inches in diameter and mature over several months for harvest in the autumn. These types are firm and dry, and take well to braising and roasting. And there are the large, long white Asian radishes, best known by the j.a.panese term daikon, daikon, which can be more than a foot/25 cm long and weigh 6 lb/3 kg. They are relatively mild and used both raw and cooked, sometimes almost as a crisp pear might be. Radish pungency is created by an enzyme reaction that forms a volatile mustard oil (p. 321). Much of that enzyme is found in the skin, so peeling will moderate the pepperiness. Though most often eaten raw or pickled, radishes can be cooked like turnips, a treatment that minimizes their pungency (the enzyme is inactivated) and brings out their sweetness. which can be more than a foot/25 cm long and weigh 6 lb/3 kg. They are relatively mild and used both raw and cooked, sometimes almost as a crisp pear might be. Radish pungency is created by an enzyme reaction that forms a volatile mustard oil (p. 321). Much of that enzyme is found in the skin, so peeling will moderate the pepperiness. Though most often eaten raw or pickled, radishes can be cooked like turnips, a treatment that minimizes their pungency (the enzyme is inactivated) and brings out their sweetness.

An unusual radish species, R. caudatus, R. caudatus, is known as the "rat-tailed radish" because it bears long edible seedpods. is known as the "rat-tailed radish" because it bears long edible seedpods.

The Onion Family: Onions, Garlic, Leeks There are around 500 species in the genus Allium, Allium, a group of plants in the lily family that are native to northern temperate regions. About 20 are important human foods, and a handful have been prized for thousands of years, as is attested by the well-known lament of the exiled Israelites in the Old Testament: "We remember the fish, which we did eat in Egypt freely; the cuc.u.mbers, and the melons, and the leeks, and the onions, and the garlic." Onions, garlic, and most of their relatives are grown primarily for their underground bulbs, which are made up of swollen leaf bases or "scales" that store energy for the beginning of the next growing season, and which naturally keep well for months. Like the sunchoke and its relatives, the onion family acc.u.mulates energy stores not in starch, but in chains of fructose sugars (p. 805), which long, slow cooking breaks down to produce a marked sweetness. Of course the fresh green leaves of bulb-forming alliums are also eaten, and nonbulbing kinds, including leeks, chives, and some onions, give only their leaves. a group of plants in the lily family that are native to northern temperate regions. About 20 are important human foods, and a handful have been prized for thousands of years, as is attested by the well-known lament of the exiled Israelites in the Old Testament: "We remember the fish, which we did eat in Egypt freely; the cuc.u.mbers, and the melons, and the leeks, and the onions, and the garlic." Onions, garlic, and most of their relatives are grown primarily for their underground bulbs, which are made up of swollen leaf bases or "scales" that store energy for the beginning of the next growing season, and which naturally keep well for months. Like the sunchoke and its relatives, the onion family acc.u.mulates energy stores not in starch, but in chains of fructose sugars (p. 805), which long, slow cooking breaks down to produce a marked sweetness. Of course the fresh green leaves of bulb-forming alliums are also eaten, and nonbulbing kinds, including leeks, chives, and some onions, give only their leaves.

The key to the onion family's appeal is a strong, often pungent, sulfury flavor whose original purpose was to deter animals from eating the plants. Cooking transforms this chemical defense into a deliciously savory, almost meaty quality that adds depth to many dishes in many cultures.

The Flavors and Sting of Raw Alliums The distinctive flavors of the onion family come from its defensive use of the element sulfur. The growing plants take up sulfur from the soil and incorporate it into four different kinds of chemical ammunition, which float in the cell fluids while their enzyme trigger is held separately in a storage vacuole (p. 261). When the cell is damaged by chopping or chewing, the enzyme escapes and breaks the ammunition molecules in half to produce irritating, strong-smelling sulfurous molecules. Some of these are very reactive and unstable, so they continue to evolve into other compounds. The mixture of molecules produced creates the food's raw flavor, and depends on the initial ammunition, how thoroughly the tissue is damaged, how much oxygen gets into the reactions, and how long the reactions go on. Onion flavor typically includes apple-like, burning, rubbery, and bitter notes; leek flavor has cabbage-like, creamy, and meaty aspects, while garlic seems especially potent because it produces a hundredfold higher concentration of initial reaction products than do other alliums. Chopping, pounding in a mortar, and pureeing in a food processor all give distinctive results. Chopped alliums to be eaten raw - as a garnish or in an uncooked sauce - are best rinsed to remove all the sulfur compounds from the damaged surfaces, since these tend to become harsher with time and exposure to the air.

Onion and garlic bulbs. The bulbs in the onion family consist of a central stem bud and surrounding leaf bases, which swell with stored nutrients during one growing season and then supply them to the bud in the next.

One sulfur product is produced in significant quant.i.ties only in the onion, shallot, leek, chive, and rakkyo: the "lacrimator," which causes our eyes to water. This volatile chemical escapes from the damaged onion into the air, and lands in the onion cutter's eyes and nose, where it apparently attacks nerve endings directly, then breaks down into hydrogen sulfide, sulfur dioxide, and sulfuric acid. A very effective molecular bomb! Its effects can be minimized by prechilling the onions for 3060 minutes in ice water. This treatment slows the ammunition-breaking enzyme down to a crawl, and gives all the volatile molecules less energy to launch themselves into the air. It also hydrates the papery onion skin, which makes it tougher and less brittle, and so easier to peel off.

The Flavors of Cooked Alliums When onions and their relatives are heated, the various sulfur compounds react with each other and with other substances to produce a range of characteristic flavor molecules. The cooking method, temperature, and medium strongly affect the flavor balance. Baking, drying, and microwaving tend to generate trisulfides, the characteristic notes of overcooked cabbage. Cooking at high temperatures in fat produces more volatiles and a stronger flavor than do other techniques. Relatively mild garlic compounds persist in b.u.t.ter but are changed to rubbery, pungent notes in more reactive unsaturated vegetable oils. Blanching whole garlic apparently inactivates the flavor-generating enzyme and limits its action, so the flavor of garlic cooked whole is only slightly pungent, and sweet, nutty notes come to the fore. Similarly, pickled garlic and onions are relatively mild. When onions and their relatives are heated, the various sulfur compounds react with each other and with other substances to produce a range of characteristic flavor molecules. The cooking method, temperature, and medium strongly affect the flavor balance. Baking, drying, and microwaving tend to generate trisulfides, the characteristic notes of overcooked cabbage. Cooking at high temperatures in fat produces more volatiles and a stronger flavor than do other techniques. Relatively mild garlic compounds persist in b.u.t.ter but are changed to rubbery, pungent notes in more reactive unsaturated vegetable oils. Blanching whole garlic apparently inactivates the flavor-generating enzyme and limits its action, so the flavor of garlic cooked whole is only slightly pungent, and sweet, nutty notes come to the fore. Similarly, pickled garlic and onions are relatively mild.

The sugar and sugar-chain content of onions and garlic is largely responsible for their readiness to brown when fried, and contributes a caramel note to the cooked flavor.

Food Words: Onion, Garlic, Shallot, Scallion Onion, Garlic, Shallot, ScallionVegetable names in the onion family come from diverse sources. Onion Onion itself comes from the Latin for "one," "oneness," "unity," and was the name given by Roman farmers to a variety of onion ( itself comes from the Latin for "one," "oneness," "unity," and was the name given by Roman farmers to a variety of onion (cepa) that grew singly, without forming multiple bulbs as garlic and shallots do. Garlic Garlic is an Anglo-Saxon word that meant "spear-leek": a leek with a slim, pointed leaf blade rather than a broad, open one. And both is an Anglo-Saxon word that meant "spear-leek": a leek with a slim, pointed leaf blade rather than a broad, open one. And both shallot shallot and and scallion scallion come via Latin from Ashqelon, the Hebrew name for a city in what in cla.s.sical times was southwest Palestine. come via Latin from Ashqelon, the Hebrew name for a city in what in cla.s.sical times was southwest Palestine.

Onions and Shallots Onions are plants of the species Onions are plants of the species Allium cepa, Allium cepa, which originated in central Asia but has spread across the globe in hundreds of different varieties. There are two major categories of market onions in the United States, defined not by variety but by season and harvesting practice. Spring or short-day onions are planted as seedlings in the late fall, and harvested before they're fully mature in the next spring and early summer. They're relatively mild and moist and perishable, and best kept in the refrigerator. A special category of spring onion is the "sweet" onion - "mild" is more accurate - which is usually a standard yellow spring onion grown in sulfur-poor soils, and therefore endowed with half or less of the usual amounts of sulfur-containing defensive chemicals. The second major kind of market onion is the storage onion, grown through the summer and harvested when mature in the fall, rich in sulfur compounds, drier, and easily stored in cool conditions for several months. which originated in central Asia but has spread across the globe in hundreds of different varieties. There are two major categories of market onions in the United States, defined not by variety but by season and harvesting practice. Spring or short-day onions are planted as seedlings in the late fall, and harvested before they're fully mature in the next spring and early summer. They're relatively mild and moist and perishable, and best kept in the refrigerator. A special category of spring onion is the "sweet" onion - "mild" is more accurate - which is usually a standard yellow spring onion grown in sulfur-poor soils, and therefore endowed with half or less of the usual amounts of sulfur-containing defensive chemicals. The second major kind of market onion is the storage onion, grown through the summer and harvested when mature in the fall, rich in sulfur compounds, drier, and easily stored in cool conditions for several months.

White onion varieties are somewhat moister and don't keep quite as well as yellow onions, which owe their color to phenolic flavonoid compounds. Red onions are pigmented by water-soluble anthocyanins, but only in the surface layers of each leaf scale, so cooking dilutes and dulls their color.

Green onions, or scallions, can be either bulb-forming onion varieties harvested quite young, or special varieties that never do form bulbs. Shallots are a distinctive, cl.u.s.tering variety of onion whose bulbs are smaller, finer-textured, and somewhat milder and sweeter, often with a purple coloration. They're especially valued in France and southeast Asia.

Garlic Garlic is the central Asian native Garlic is the central Asian native Allium sativum, Allium sativum, which produces a tight head of a dozen or more bulbs, or "cloves." "Elephant garlic" is actually a bulbing variety of leek, with a milder flavor, and "wild garlic" yet another species, which produces a tight head of a dozen or more bulbs, or "cloves." "Elephant garlic" is actually a bulbing variety of leek, with a milder flavor, and "wild garlic" yet another species, A. ursinum. A. ursinum. Unlike multilayered onion bulbs, garlic cloves consist of a single swollen storage leaf surrounding the young shoot. That leaf contains much less water than onion scales do - under 60% of its weight, compared to 90% for onions - and a much higher concentration of fructose and fructose chains, so during frying or roasting it dries out and browns much quicker than onions do. Unlike multilayered onion bulbs, garlic cloves consist of a single swollen storage leaf surrounding the young shoot. That leaf contains much less water than onion scales do - under 60% of its weight, compared to 90% for onions - and a much higher concentration of fructose and fructose chains, so during frying or roasting it dries out and browns much quicker than onions do.

Important Members of the Onion Family Onions, scallions

Allium cepa Allium cepa

Shallots

Allium cepa Allium cepa var. var. ascalonic.u.m ascalonic.u.m

Garlic

Allium sativum Allium sativum

Leeks, wild

Allium ampeloprasum Allium ampeloprasum

Leeks, cultivated

Allium ampeloprasum Allium ampeloprasum var. var. porrum porrum

Great-headed (elephant) garlic

Allium ampeloprasum Allium ampeloprasum var. var. gigante gigante

Leeks, Egyptian

Allium kurrat Allium kurrat

Ramps, ramson (broad-leaf leek)

Allium tricocc.u.m Allium tricocc.u.m

Chives

Allium schoenoprasum Allium schoenoprasum

Chives, "garlic" or "Chinese"

Allium tuberosum Allium tuberosum

j.a.panese long onion

Allium ramosum Allium ramosum

j.a.panese bunching onion

Allium fistulosum Allium fistulosum