Tofu

Tofu
Seasoned tofu cubes in a Chinese dish
Chinese name
Traditional Chinese	荳腐 or 豆腐
Simplified Chinese	豆腐
Hanyu Pinyin	dòufu
Literal meaning	bean curd
Transliterations Hakka - Romanization teu55 fu55 Mandarin - Hanyu Pinyin dòufu - Wade–Giles tou-fu Min - Hokkien POJ tāu-hū Wu - Romanization deu去 vu去 (Wuu Pinyin) [dɤɯ.vʊ] (IPA) Cantonese - Jyutping dau6-fu6 - Yale Romanization dauh-fuh
Filipino name
Tagalog	tokwa
Japanese name
Kanji	豆腐
Hiragana	とうふ
Transliterations - Revised Hepburn tōfu - Kunrei-shiki tôhu
Korean name
Hangul	두부
Hanja	豆腐
Transliterations - Revised Romanization dubu[1][2] - McCune- Reischauer tubu
Malay name
Malay	tauhu
Tamil name
Tamil	tahu
Thai name
Thai	เต้าหู้ [tâohûː]
Vietnamese name
Vietnamese	đậu phụ or đậu hũ or tàu hũ
Min Bei name
Min Bei	dae fu (Jian'ou dialect)
Indonesian name
Indonesian	tahu

Tofu (豆腐, Chinese dòufu, Japanese tōfu, Korean doobu^?), or bean curd^[3] is a food made by coagulating soy milk, and then pressing the resulting curds into soft white blocks. It is of Chinese origin,^[4] and part of East Asian and Southeast Asian cuisine such as Chinese, Japanese, Korean, Indonesian, Vietnamese,^[5] and others.^[6] There are many different varieties of tofu, including fresh tofu and tofu that has been processed in some way. Tofu has very little flavor or smell on its own, so it can be used either in savory or sweet dishes, and is often seasoned or marinated to suit the dish.

Tofu originated in the Han dynasty in ancient China.^[4] Li Shizhen in the Ming Dynasty described a method of making tofu in Bencao Gangmu.^[7] Tofu and its production technique were subsequently introduced into Korea, then Japan^[8][9][10] during the Nara period. It also spread into other parts of East Asia as well.^[11] This spread likely coincided with the spread of Buddhism as it is an important source of protein in the vegetarian diet of East Asian Buddhism.^[8]

Tofu is low in calories, contains a relatively large amount of iron, and contains little fat. Depending on the coagulant used in manufacturing, the tofu may also be high in calcium and/or magnesium.

Etymology

The English word "tofu" comes from the Japanese tōfu (豆腐), listen which itself derives from the Chinese dòufu (豆腐 or 荳腐) from "bean" (豆) plus "curdled" or "fermented" (腐).^[12][13]

The English term "bean curd(s)" for tofu has been used since at least 1840.^[14]

Production

Tofu is made by coagulating soy milk and pressing the resulting curds. Although pre-made soy milk may be used, most tofu producers begin by making their own soy milk, which is produced by soaking, grinding, boiling and straining dried (or, less commonly, fresh) soybeans.

Coagulation of the protein and oil (emulsion) suspended in the boiled soy milk is the most important step in the production of tofu. This process is accomplished with the aid of coagulants. Two types of coagulants (salts and acids) are used commercially.^[15] The third type of coagulant, enzymes, is not yet used commercially but shows potential for producing both firm and "silken" tofu.

Salt coagulants

• Calcium sulfate (gypsum): The traditional and most widely used coagulant to produce Chinese-style tofu. It produces a tofu that is tender but slightly brittle in texture. The coagulant itself has no perceivable taste. Use of this coagulant also makes a tofu that is rich in calcium. As such, many tofu manufacturers choose to use this coagulant to be able to market their tofu as a good source of dietary calcium.

• Chloride-type Nigari salts or Lushui ( Traditional: 鹵水, 滷水; Simplified:卤水) - Magnesium chloride and calcium chloride: Both of these salts have a high solubility rate in water and affect soy protein in the same way, whereas gypsum is only very slightly soluble in water and acts differently in soy protein precipitation, the basis for tofu formation. These are the coagulants used to make tofu with a smooth and tender texture. In Japan, a white powder called nigari, which consists primarily of magnesium chloride, is produced from seawater after the sodium chloride is removed and the water evaporated. Depending on its production method, nigari/Lushui may also contain small quantities of magnesium sulfate (Epsom salt), potassium chloride, calcium chloride, and trace amounts of other naturally occurring salts. Although the term nigari is derived from nigai, the Japanese word for "bitter," neither nigari nor pure magnesium chloride imparts a perceivable taste to the finished tofu. Calcium chloride is a common coagulant for tofu in North America.^[16] Fresh clean sea water itself can also be used as a coagulant.^[17]

Acid coagulants

• Glucono delta-lactone (GDL): A naturally occurring organic acid also used in cheese making, which produces a very fine textured tofu that is almost jelly-like. This coagulant is used especially for "silken" and softer tofus, and confers an almost imperceptible sour taste to the finished product.^[18] Commonly used together with calcium sulfate to give soft tofu a smooth tender texture.

Enzyme coagulants

• Among enzymes that have been shown to produce tofu are papain, and alkaline and neutral proteases from microorganisms. In the case of papain, the enzyme to substrate ratio, by weight, was held constant at 1:400. An aliquot of 1% crude papain was added to "uncooked" soy milk at room temperature and heated to 90–100 °C.^[16]

Contemporary tofu manufacturers may choose to use one or more of these coagulants, since they each play a role in producing a desired texture in the finished tofu.^[18] Different textures result from different pore sizes and other microscopic features in tofus produced using each coagulant. The coagulant mixture is dissolved into water, and the solution is then stirred into boiled soy milk until the mixture curdles into a soft gel.^[15]

One of the stages in making tofu, the coagulated soya curd is having the water pressed out of it to produce the solid tofu bricks that appear in shops.

The curds are processed differently depending on the form of tofu that is being manufactured. For soft silken tofu (嫩豆腐; nèn dòufu) or tofu flower (豆花, dòuhuā) the soy milk is curdled directly in the tofu's selling package. For standard firm Asian tofu, the soy curd is cut and strained of excess liquid using cheese cloth or muslin and then lightly pressed to produce a soft cake. Firmer tofus, such as Asian dry tofu (豆乾) or Western types of tofu, are further pressed to remove even more liquid. In Vietnam, the curd is strained and molded in a square mold and the end product is called đậu khuôn (molded bean) or đậu phụ (one of the Vietnamese ways to pronounce the Chinese doufu). The tofu curds are allowed to cool and become firm. The finished tofu can then be cut into pieces, flavored or further processed.

Although tartness is sometimes desired in dessert tofu, the acid used in flavoring is usually not the primary coagulant since it is not desirable to the flavor or texture of the resulting tofu to add it in a sufficiently high concentration so as to induce coagulation. A sour taste in tofu and a slight cloudiness in its storing liquid is also usually an indication of bacterial growth and, hence, spoilage.

Varieties

There is a wide variety of tofu available in both Western and Eastern markets. Despite the daunting variety, tofu products can be split into two main categories: fresh tofu, which is produced directly from soy milk, and processed tofu, which is produced from fresh tofu. Tofu production also creates important side products which are often used in various cuisines.

Fresh tofu

Depending on the amount of water that is extracted from the tofu curds, fresh tofu can be divided into three main varieties.

Silken tofu with soy sauce and a decorative carrot slice

Soft/silken tofu

Soft/silken tofu(嫩豆腐 or 滑豆腐, nèn dòufu or huá dòufu, in Chinese, lit. "soft tofu" or "smooth tofu"; 絹漉し豆腐, kinugoshi tōfu in Japanese, lit. "silk-filtered tofu"; 순두부, 純豆腐, sundubu in Korean, lit. "pure tofu") is undrained tofu that contains the highest moisture content of all fresh tofus.^[19] Its texture can be described as similar to that of very fine custard. In Japan and Korea, traditional soft tofu is made with seawater.^{[20][21][22][23][24]}

Douhua (豆花, dòu huā or 豆腐花, dòufu huā in Chinese), or tofu brain (豆腐腦 or 豆腐脑, dòufu naǒ in Chinese), often eaten as a dessert, but sometimes with salty pickles or hot sauce added instead, is another type of soft tofu with an even higher moisture content. Because it is nearly impossible to pick up this type of tofu with chopsticks, it is generally eaten with a spoon. With the addition of flavorings such as finely chopped spring onions, dried shrimp, soy sauce, chilli sauce, douhua is a popular breakfast dish across China. In Malaysia, douhua is usually warm-served with white or dark (palm) sugar water, or cold-served with longan.

Some variation exists among soft tofus. Black douhua (黑豆花) is a type of silken tofu made from plain black soy beans and soybeans, which is usually made into dòuhuā (豆花) rather than firm or dry tofu. The texture of black bean tofu is slightly more gelatinous than regular douhua and the color is greyish in tone. This type of tofu is eaten for the earthy "black bean taste."Edamame tofu is a Japanese variety of kinugoshi tōfu made from edamame (fresh green soybeans); it is pale green in color and often studded with whole edamame.

Firm tofu

Firm tofu (called 老豆腐 lǎo dòufu in Chinese; 木綿豆腐, momendōfu in Japanese, lit. "cotton tofu"): Although drained and pressed, this form of fresh tofu still contains a great amount of moisture. It has the firmness of raw meat but bounces back readily when pressed. The texture of the inside of the tofu is similar to that of a firm custard. The skin of this form of tofu has the pattern of the muslin used to drain it and is slightly more resilient to damage than its inside. It can be picked up easily with chopsticks.^[19][25]

Dried tofu

Dried tofu (豆乾, dòu gān in Chinese, lit. "dry tofu"): An extra firm variety of tofu with the least amount of moisture of all fresh tofu. It has the firmness of fully cooked meat and a somewhat rubbery feel similar to paneer. When sliced thinly, this tofu can be crumbled easily. The skin of this form of tofu has the pattern of the muslin used to drain and press it. Western firm tofu is milled and reformed after the pressing and sometimes lacks the skin with its cloth patterning. One variety of dried tofu is pressed especially flat and sliced into long strings with a cross section smaller than 2 mm × 2 mm. Shredded dried tofu (豆乾絲, dòu gān sī in Chinese, or simply 乾絲, gān sī), which looks like loose cooked noodles, and can be served cold, stir-fried, or similar in style to Japanese aburaage.^[25][26] Fresh tofu is usually sold completely immersed in water to maintain its moisture content.

Processed tofu

Many forms of processed tofus exist, due to the varied ways in which fresh tofu can be used. Some of these techniques likely originate from the need to preserve tofu before the days of refrigeration, or to increase its shelf life and longevity. Other production techniques are employed to create tofus with unique textures and flavors.^[27]

Fermented

Sliced and sun dried tofu

• Pickled tofu (豆腐乳 in Chinese, pinyin: dòufu rǔ, lit. "tofu dairy," or 腐乳; chao in Vietnamese): Also called "preserved tofu" or "fermented tofu," this food consists of cubes of dried tofu that have been allowed to fully air-dry under hay and slowly ferment from aerial bacteria.^[27] The dry fermented tofu is then soaked in salt water, Chinese wine, vinegar, and minced chiles, or a unique mixture of whole rice, bean paste, and soybeans. In the case of red pickled tofu (紅豆腐乳 in Chinese, Pinyin: hóng dòufu rǔ), red yeast rice (cultivated with Monascus purpureus) is added for color.^[28]
• Stinky tofu (臭豆腐 in Chinese, Pinyin: chòu dòufu): A soft tofu that has been fermented in a unique vegetable and fish brine.^[27] The blocks of tofu smell strongly of certain pungent cheeses, and are described by many as rotten and fecal. Despite its strong odor, the flavor and texture of stinky tofu is appreciated by aficionados, who describe it as delightful. The texture of this tofu is similar to the soft Asian tofu that it is made from. The rind that stinky tofu develops from frying is said to be especially crisp, and is usually served with soy sauce, sweet sauce, and/or hot sauce.

Flavored

Almond "tofu," which is not made of soy milk but rather from gelatin or agarose

Chili-peppered egg tofu from Ipoh, Malaysia.

Flavors can be mixed directly into curdling soy milk while the tofu is being produced.

• Sweet: Common sweet dessert tofus include peanut tofu (落花生豆腐, luòhuāshēng dòufu in Chinese and jimami-dōfu in Japanese), almond tofu (杏仁豆腐, xìngrén dòufu in Chinese; 杏仁豆腐, annindōfu in Japanese), mango tofu, coconut tofu and longan tofu (龙眼豆花). In order to produce these forms of tofu, sugar, fruit acids, and flavorants are mixed into soy milk prior to curdling. Most sweet tofus have the texture of silken tofu and are served cold.
  • Products called "almond tofu" in some cases are actually not tofu but are instead gelatinous mixtures including agar or gelatin and whitened with milk or coconut milk. In Japan these are canned with syrup and sold as sweet desserts.
• Savory: Egg tofu (Japanese: 玉子豆腐, 卵豆腐, tamagodōfu) (Chinese: 蛋豆腐, dàn dòufu; often called 日本豆腐, rìbĕn dòufu, lit. "Japan bean curd") is the main type of savory flavored tofu. Whole beaten eggs are filtered and incorporated into the soy milk before the coagulant is added. The mixture is filled into plastic tubes and allowed to curdle. The tofu is then cooked in its packaging and sold. Egg tofu has a pale golden color that can be attributed to the addition of egg and, occasionally, food coloring. This tofu has a fuller texture and flavor than silken tofu, which can be attributed to the presence of egg fat and protein.

Fried

• With the exception of the softest tofus, all forms of tofu can be fried. Thin and soft varieties of tofu are deep fried in oil until they are light and airy in their core (豆泡 dòupào, 豆腐泡 doufupao, 油豆腐 youdoufu, or 豆卜 doubu in Chinese, literally "bean bubble," describing the shape of the fried tofu as a bubble).
• Tofus such as firm Asian and dry tofu, with their lower moisture content, are cut into bite-sized cubes or triangles and deep fried until they develop a golden-brown, crispy surface (炸豆腐 in Chinese, zhà dòufu, lit. "fried tofu"). These may be eaten on their own or with a light sauce, or further cooked in liquids; they are also added to hot pot dishes or included as part of the vegetarian dish called luohan zhai.
• Aburaage (油揚げ): Japanese fried tofu for Inari-sushi.

Frozen

Thawed and sliced frozen tofu

• Thousand layer tofu (千葉豆腐, 凍豆腐 or 冰豆腐 in Chinese, literally "thousand layer tofu" or "frozen tofu"): By freezing tofu, the large ice crystals that develop within the tofu result in the formation of large cavities that appear to be layered (pseudostratified). The frozen tofu takes on a yellowish hue in the freezing process. Thousand layer tofu is commonly made at home from Asian soft tofu though it is also commercially sold as a specialty in parts of Taiwan. This tofu is defrosted and sometimes squeezed of moisture prior to use.
• Koyadofu (kōyadōfu, 高野豆腐 in Japanese): The name comes from Mount Koya, a center of Japanese Buddhism famed for its shōjin ryōri, or traditional Buddhist vegetarian cuisine. It is sold in freeze-dried blocks or cubes in Japanese markets. It must be soaked in water before eating, and is typically simmered in dashi, sake or mirin and soy sauce. In shōjin ryōri, vegetarian kombu dashi, made from seaweed, is used. When prepared in the usual manner, it has a spongy texture and mild sweet and savory flavor. A similar form of freeze-dried tofu, in smaller pieces, is found in instant soups (such as miso soup), in which the toppings are freeze-dried and stored in sealed pouches.

Tofu is also a main dish, especially this type which is commonly used and is in high demand in eastern Asia.

Byproducts of tofu production

Tofu production creates some edible byproducts. Food products are made from the protein-oil film, or "skin," which forms over the surface of boiling soy milk in an open shallow pan. The leftover solids from pressing soy milk are called okara.

Tofu skin

Tofu skin is produced through the boiling of soy milk, in an open shallow pan, thus producing a film or skin composed primarily of a soy protein-lipid complex on the liquid surface. The films are collected and dried into yellowish sheets known as soy milk skin (腐皮, fǔ pí in Chinese; 湯葉, yuba in Japanese). Its approximate composition is : 50–55% protein, 24–26% lipids (fat), 12% carbohydrate, 3% ash, and 9% moisture.^[29]

The skin can also be bunched up to stick form and dried into something known as "tofu bamboo" (腐竹, fǔ zhú in Chinese; phù trúc in Vietnamese; kusatake, Japanese), or myriad other forms. Since tofu skin has a soft yet rubbery texture, it is folded or shaped into different forms and cooked further to imitate meat in vegan cuisine.

Some factories dedicate production to tofu skin and other soy membrane products.

Okara

Okara (おから^?) (雪花菜, xuě huā caì, lit. "snowflake vegetable"; 豆腐渣, dòufu zhā, lit. "tofu sediment/residue"; kongbiji, 콩비지 in Korean), sometimes known in the west as "soy pulp" or "tofu lees",^[30] is the fibre, protein, and starch left over when soy milk has been extracted from ground soaked soybeans.^[31] Although it is mainly used as animal feed in most tofu producing cultures, it is sometimes used in Japanese and Korean cuisines. It is also an ingredient for vegetarian burgers produced in many western nations.

Non-tofu "tofus"

Due to their Asian origins and their textures, many food items are called "tofu" even though their production processes are not technically similar. For instance, many sweet almond tofus are actually gelatinous desserts made from agar or gelatin and whitened with milk or coconut milk more similar to Japanese anmitsu. As well, some foods such as Burmese tofu are not coagulated from the "milk" of the legume but rather set in a manner similar to soft polenta, Korean muk, or the jidou liangfen of Yunnan province of Southwest China.

Burmese tofu

To hpu (Burmese tofu), in two forms: fresh and fritters

Burmese tofu (to hpu in Burmese) is a type of legume product made from besan (chana dal) flour the Shan variety uses yellow split pea flour instead. Both types are yellow in color and generally found only in Myanmar, though the Burman variety is also available in some overseas restaurants serving Burmese cuisine.^[32]

Burmese tofu may be fried as fritters cut in rectangular or triangular shapes. Rice tofu, called hsan to hpu (or hsan ta hpo in Shan regions) is made from rice flour (called hsan hmont or mont hmont) and is white in color, with the same consistency as yellow Burmese tofu when set. It is eaten as a salad in the same manner as yellow tofu.

Preparation

Tofu has very little flavor or smell on its own. Consequently tofu can be prepared either in savory or sweet dishes, acting as a bland background for presenting the flavors of the other ingredients used. As a method of flavoring it is often marinated in soy sauce, chilis, sesame oil, etc.

Eastern methods

In Asian cooking, tofu is eaten in myriad ways, including raw, stewed, stir-fried, in soup, cooked in sauce, or stuffed with fillings. The idea of using tofu as a meat substitute is not common in East Asia. Many Chinese tofu dishes such as jiā cháng dòu fǔ (家常豆腐)and má pó dòu fú (麻婆豆腐) include meat.

Lightly flavored

In Japan, a common lunch in the summer months is hiyayakko (冷奴), silken or firm Asian tofu served with freshly grated ginger, scallions, and soy sauce. In many parts of China, fresh tofu is similarly eaten with soy sauce or further flavored with katsuobushi shavings, century eggs (皮蛋), and sesame seed oil.

Dòuhuā (豆花), is a soft tofu dish. The fresh tofu is served warm and here dressed with sweet syrup. Lamma Island, Hong Kong.

In Chinese cuisine, Dòuhuā (豆花) is served with toppings like boiled peanuts, azuki beans, cooked oatmeal, tapioca, mung beans and a syrup flavored with ginger or almond. During the summer, dòuhuā is served with crushed ice; in the winter, it is served warm.^[33]

In Korean cuisine, dubu jorim (두부조림) consists of pan fried cubes of firm tofu, seasoned with soy sauce, garlic, and other ingredients. Cubes of cold, uncooked firm tofu seasoned with soy sauce, scallions, and ginger, prepared in a manner similar to the Japanese hiyayakko, are also enjoyed. The popular bar food, or anju (안주), called dubu kimchi (두부김치), features boiled, firm tofu served in rectangular slices around the edges of a plate with pan fried, sautéed or freshly mixed kimchi (김치) in the middle.

In the Philippines, the sweet delicacy taho is made of fresh tofu with brown sugar syrup and sago. The Malaysian version of taho or douhua is called tofufa. Warm soft tofu is served in 'slices' (due to being scooped using a flat spoon from a wooden bucket) in a bowl with either pandan-flavored sugar syrup or palm sugar syrup.

In Vietnam, dòuhuā is pronounced đậu hủ. This variety of soft tofu is made and carried around in an earthenware jar. It is served by being scooped into a bowl with a very shallow and flat spoon, and eaten with either powdered sugar and lime juice or with a ginger-flavored syrup. It is generally eaten hot, even during summer.

Fried

A common cooking technique in many parts of East and Southeast Asia involves deep frying tofu in vegetable oil, sunflower oil, and canola oil to varied results. Although tofu is often sold preprocessed into fried items, pre-fried tofu is seldom eaten directly and requires additional cooking. Depending on the type of tofu used, the texture of deep fried tofu may range from crispy on the outside and custardy on the inside, to puffed up like a plain doughnut. The former is usually eaten plain in Chinese cuisine with garlic soy sauce, while the latter is either stuffed with fish paste or cooked in soups.^[33] In Japan, cubes of lightly coated and fried tofu topped with a kombu dashi-based sauce are called agedashi-dofu (揚げ出し豆腐). Soft tofu that has been thinly sliced and deep fried, known as aburage in Japan and yubu (유부) in Korea, is commonly blanched, seasoned with soy sauce and mirin and served in dishes such as kitsune udon. Aburage is sometimes also cut open to form a pocket and stuffed with sushi rice; this dish is called inarizushi (稲荷寿司) and is also popular in Korea, where it is called yubu chobap (유부초밥)

Soups, stews, and braised dishes

Yudofu, or tofu in hot water.

A rather famous hot Sichuan preparation using firm Asian tofu is mápó dòufu (麻婆豆腐). This involves braised tofu in a beef, chili, and a fermented bean paste sauce. In the Shanghai region it is called málà dòufu (麻辣豆腐).

Dried tofu is usually not eaten raw but first stewed in a mixture of soy sauce and spices. Some types of dried tofu are preseasoned with special blends of spices, so that the tofu may either be called "five spice tofu" (五香豆腐) or "soy sauce stewed tofu" (鹵水豆腐). Dried tofu is typically served thinly sliced with chopped green onions or with slices of meat for added flavor. Most dried tofu is sold after it has been fried or pre-stewed by tofu vendors.^[33]

Soft tofu can also be broken up or mashed and mixed with raw ingredients prior to being cooked. For example, Japanese ganmodoki is a mixture of chopped vegetables and mashed tofu. The mixture is bound together with starch and deep fried. Chinese families sometimes make a steamed meatloaf or meatball dish from equal parts of coarsely mashed tofu and ground pork. In India, tofu is also used as a low fat replacement for paneer providing the same texture with similar taste.

Tofu bamboos are often used in lamb stew or in a dessert soup. Tofu skins are often used as wrappers in dim sum. Freeze-dried tofu and frozen tofu are rehydrated and enjoyed in savory soups. These products are often taken along on camping trips since a small bag of these dried tofu can provide protein for many days.

In Korean cuisine, soft tofu, called sundubu (순두부), is used to make a thick stew called sundubu jjigae (순두부 찌개). Firm, diced tofu often features in the staple stews doenjang jjigae (된장 찌개) and kimchi jjigae (김치 찌개).

Bacem

In Java, Indonesia, tofu is often cooked in bacem method, along with tempeh and chicken. Tofu is boiled in coconut water, mixed with galangal root, Indonesian bay leaf, coriander, shallot, garlic, tamarind and palm sugar. After the spicy coconut water is completely evaporated, the tofu is fried until it has golden brown color. The result is spicy and sweet tofu, while slightly crisp on the edges. This cooked tofu variant is commonly known as tahu bacem in Indonesian.

As flavoring

Pickled tofu is commonly used in small amounts together with its soaking liquid to flavor stir-fried or braised vegetable dishes (particularly leafy green vegetables like water spinach). It is often eaten directly as a condiment with rice or congee.

Western methods

Generally, the firmer styles of tofu are used for kebabs, mock meats, and dishes requiring a consistency that holds together, while the softer styles can be used for desserts, soups, shakes, and sauces.

Firm western tofus can be barbecued since they will hold together on a barbecue grill. These types of tofu are usually marinated overnight as the marinade does not easily penetrate the entire block of tofu (techniques to increase penetration of marinades are stabbing repeatedly with a fork or freezing and thawing prior to marinating). Grated firm western tofu is sometimes used in conjunction with TVP as a meat substitute. Softer tofus are sometimes used as a dairy-free or low-calorie filler. Silken tofu may be used to replace cheese in certain dishes (such as lasagna).

Tofu has also been fused into other cuisines in the west, for instance used in Indian-style curries.

Tofu and soy protein can be industrially processed to match the textures and flavors to the likes of cheese, pudding, eggs, bacon etc. Tofu's texture can also be altered by freezing, pureeing, and cooking. In the Americas, Europe, Australia and New Zealand, tofu is frequently associated with vegetarianism and veganism as it is a source of high-quality, non-animal protein.

History

Tofu and potatoes grilled at a street stall in Yuanyang, Yunnan province, China

Tofu originated in ancient China,^[4] although little else is known about the exact historic origins of tofu and its method of production. While there are many theories regarding tofu's origins, historical information is scarce enough as to relegate the status of most theories to either speculation or legend. Like the origins of cheese and butter, the exact origin of tofu production may never be known or proven.

What is known is that tofu production is an ancient technique. Tofu was widely consumed in ancient China, and techniques for its production and preparation were eventually spread to many other parts of Asia.

Three theories of origin

The most commonly held of the three theories of tofu's origin maintains that tofu was invented in northern China around 164 BC by Lord Liu An, a Han Dynasty prince. Although this is possible, the paucity of concrete information about this period makes it difficult to conclusively determine whether Liu An invented the method for making tofu. Furthermore, in Chinese history, important inventions were often attributed to important leaders and figures of the time.^[25] In 1960, a stone mural unearthed from an Eastern Han dynasty tomb provided support for the theory of Han origin of tofu, however some scholars maintained that the tofu in Han dynasty was rudimentary, and lacked the firmness and taste of real tofu.^[34]

Another theory states that the production method for tofu was discovered accidentally when a slurry of boiled, ground soybeans was mixed with impure sea salt. Such sea salt would likely have contained calcium and magnesium salts, allowing the soy mixture to curdle and produce a tofu-like gel.^[35] This may have possibly been the way that tofu was discovered, since soy milk has been eaten as a savory soup in ancient as well as modern times. Its technical plausibility notwithstanding, there is little evidence to prove or disprove that tofu production originated in this way.^[25]

The last group of theories maintains that the ancient Chinese learned the method for the curdling of soy milk by emulating the milk curdling techniques of the Mongolians or East Indians. For, despite their advancement, no technology or knowledge of culturing and processing milk products existed within ancient Chinese society. (They did not seek such technology, probably because of the Confucian taboo on fermented dairy products and other so-called "barbarian foodstuffs".) The primary evidence for this theory lies with the etymological similarity between the Chinese term for Mongolian fermented milk (rufu, which literally means "milk curdled") and the term doufu ("beans curdled") or tofu. Although intriguing and possible, there is no evidence to substantiate this theory beyond the point of academic speculation.^[25]

In Asia

Tofu as sold in Haikou, Hainan, China

Although its development likely preceded Liu An, tofu is known to have been a commonly produced and consumed food item in China by the 2nd century BC. Although the varieties of tofu produced in ancient times may not have been identical to those of today, descriptions from writings and poetry of the Song and Yuan Dynasty show that the production technique for tofu had already been standardized by then, to the extent that they would be similar to tofu of contemporary times.

In China, tofu is traditionally used as a food offering when visiting the graves of deceased relatives. It is claimed that the spirits (or ghosts) have long lost their chins and jaws, and that only tofu is soft enough for them to eat. Before refrigeration was available in China, tofu was often only sold during the winter time, due to the tofu not spoiling in the colder weather. During the warmer months, any leftover tofu would be spoiled if left for more than a day. Chinese war hero Guan Yu used to be a tofu maker before he enlisted in the army. Chinese martial arts expert and hero, Yim Wing-chun, was a celebrated tofu maker in her village. (Tofu as such plays a part in the 1994 movie about her life, Wing Chun.)

Tofu and its production technique were subsequently introduced into Japan in the Nara period (late eighth century) as well as other parts of East Asia. The earliest document of tofu in Japan shows that the dish was served as an offering at the Kasuga Shrine in Nara in 1183.^[36] The book Tofu Hyakuchin (豆腐百珍), published in the Edo period, lists 100 recipes for cooking tofu.

The rise in acceptance of tofu likely coincided with that of Buddhism as it is an important source of proteins in the religion's vegetarian diet. Since then, tofu has become a staple in many countries, including Vietnam, Thailand, and Korea, with subtle regional variations in production methods, texture, flavor, and usage.

Tofu is so highly esteemed in Korean culture that the menus of many Korean restaurants are based almost entirely on tofu, including some which feature only sundubu jjigae (a stew made with soft tofu) and gochujang (red chili paste).

Tofu in the Philippines is essential to the daily diet, as taho, widely eaten as breakfast, or tokwa (a dry fried variation), which is a staple or alternative to meat in main meals, and in numerous regional dishes. Tofu was introduced to the archipelago in the 10-13th centuries by Song Chinese mariners and merchants, along with many different foods which had become staples of the Filipino diet. The use and production of Tofu were first limited to urban centers with influential Chinese minorities, such as Tondo or Cebu, but were quickly spread to even remote native villages and islands, long before the Spanish arrival in the 17th century.

In Malaysia, Singapore, Thailand and Indonesia, tofu or tahu is widely available and used in many Malay dishes such as sayur goreng, masak lodeh, tahu sumbat, rojak, pecal, gado-gado, lontong and some curries. The Malaysian and Singaporean Indians use tofu in their cuisine such as Indian mee goreng and rojak pasembor. The makers of tofu in these countries were originally the Chinese but tofu now is made by non-Chinese as well.

In the West

The first tofu company in the USA was established in 1878.^[37] However tofu was not well known to most Westerners before the middle of the 20th century. With increased cultural contact between the West and Asia and growing interest in vegetarianism, knowledge of tofu has become widespread. Numerous types of pre-flavored tofu can be found in many supermarket chains throughout the West.

Nutrition and health information

Protein

Tofu is relatively high in protein, about 10.7% for firm tofu and 5.3% for soft "silken" tofu with about 2% and 1% fat respectively as a percentage of weight.^[38]

In 1995, a report from the University of Kentucky, financed by The Solae Company St. Louis, Missouri (the PTI division of DuPont), concluded that soy protein is correlated with significant decreases in serum cholesterol, Low Density Lipoprotein LDL (bad cholesterol) and triglyceride concentrations.^[39] However, High Density Lipoprotein HDL (good cholesterol) did not increase. Soy phytoestrogens (isoflavones: genistein and daidzein) absorbed onto the soy protein were suggested as the agent reducing serum cholesterol levels. On the basis of this research, PTI, in 1998, filed a petition with Food and Drug Administration for a health claim that soy protein may reduce cholesterol and the risk of heart disease.

The FDA granted this health claim for soy: "25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease."^[40] For instance, 100 grams of firm tofu contains 15.78 grams of soy protein.^[41] In January 2006, an American Heart Association review (in the journal Circulation) of a decade-long study of soy protein benefits showed only a minimal decrease in cholesterol levels, but it compared favorably against animal protein sources.^[42]

Isoflavones

Soy isoflavones have not been shown to reduce post menopause hot flashes in women or to help prevent cancers of the breast, uterus or prostate. Thus, soy isoflavone supplements in food or pills is not recommended.^[43]

A study done by the Pacific Health Research Institute followed over 3000 Japanese men between 1965 and 1999, which showed a positive correlation between cerebral atrophy and consumption of tofu.^[44] According to the Alzheimer's Research Trust, more research is needed.^[45]

Health issues

Two studies have shown some correlation between dementia and high tofu consumption in Javanese and Japanese American populations.^[45]
Researchers believe that this could be related to phytoestrogen and isoflavone in tofu, but no definite causality has been proven. High consumption of tofu has been linked with dementia in older age groups in more than one study, whereas in younger and middle-age age groups it might actually protect the brain.
It has been stressed that there is no evidence that eating tofu in moderation can cause any problems, and that further research is needed to confirm both the negative as well as the positive effects.^[45]

Sales and distribution

In many countries in the West, tofu can be obtained in Asian markets, farmers' markets, and health food stores. It is also increasingly available in supermarkets, especially in larger branches, and in metropolitan areas. The largest provider of tofu products in the United States is House Foods America Corp, a subsidiary of Japanese company House Foods Corp (ハウス食品).

House Foods America Corp. has tofu plants in California and New Jersey with a combined capacity of manufacturing 350,000 pieces of tofu per day. Other major brands are Vitasoy, a subsidiary of a Hong Kong based company, which also manufactures the brands Nasoya and Azumaya; and Mori-Nu (Morinaga Nutritional Foods), a subsidiary of Morinaga Milk Industry (森永乳業) of Japan, which pioneered the sale of shelf-stable, aseptically packaged tofu.

Fresh local tofu varieties are often available in Western areas with high concentrations of Asian populations.

In the East, tofu may be produced locally by relatively small vendors in the form of 2'x2'x2" block, then cut into 2"x2"x2" pieces when sold; or distributed widely by large national brands. Fresh tofu is usually bought from local vendors and is sold directly from large bins or pots at street markets. Asian firm tofu and "tofu flower" are commonly sold in this manner and are usually no more than a few hours old. Tofu that is sold by large manufacturers often comes packaged in sealed plastic cartons or tubes, and may be at most two weeks old. In Chinese supermarkets, tofu can be found in many different flavors and grades of consistency.

Most silken and flavored tofus are produced by large factories, which have the facilities to meet the required sanitary conditions for production of these forms of tofu on a large scale. In Japan, silken tofu is made daily without preservatives and is considered unsellable if it sits unsold in the supermarket for 2 days. Firm tofu is not eaten in Japan without frying as it's considered "crude".

See also

• Tempeh
• Soy milk
• Soybean
• Douhua
• Femarelle (DT56a)
• Buddhist cuisine
• Chinese cuisine
• Filipino cuisine
• Indonesian cuisine
• Japanese cuisine
• Korean cuisine
• Vegetarian cuisine
• Vietnamese cuisine
• Los Angeles Tofu Festival

Notes

References

External links

• Tofu Nutritional Value Information, About.com Vegetarian food, http://vegetarian.about.com/od/healthnutrition/p/tofunutrition.htm, retrieved 2008-01-05 
• Interview with Robyn Alderton regarding tofu itself and some related health benefits, ABC Central West NSW, http://www.abc.net.au/centralwest/stories/s398519.htm, retrieved 2008-01-05 
• Community scale manufacture of organic nigari tofu - Arcata, California, USA
• Large scale manufacture of Shan tofu (video) - Inle Lake, Myanmar

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