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Tofu
Seasoned tofu cubes in a Chinese dish
Chinese name
Chinese:	豆腐 or 荳腐
Hanyu Pinyin:	dòufǔ
Literal meaning:	bean curd
[show]Transliterations Mandarin - Hanyu Pinyin: dòufǔ - Wade-Giles: tou-fu Min - Peh-oe-ji: tāu-hū Yue (Cantonese) - Jyutping: dau6-fu6 - Yale Romanization: dauh-fuh
Filipino name
Tagalog:	tokwa
Japanese name
Kanji:	豆腐
Hiragana:	とうふ
[show]Transliterations - Revised Hepburn: tōfu - Kunrei-shiki: tôhu
Korean name
Hangul:	두부
Hanja:	豆腐
[show]Transliterations - Revised Romanization: dubu - McCune- Reischauer: tubu
Malay name
Malay:	tauhu
Tamil name
Tamil:	tahu
Thai name
Thai:	เต้าหู้ (IPA: [tâohûː])
Vietnamese name
Vietnamese:	đậu phụ or đậu hũ
Burmese name
Burmese:	(pebya/péprā:) or (tofu/tiuphü:)
Khmer name
Khmer:	តៅហ៊ូ
Indonesian name
Indonesian:	tahu

Tofu (the Japanese Romaji spelling), also called doufu (the Chinese Pinyin spelling often used in Chinese recipes) or bean curd (the literal translation), is a food of Chinese origin^[1], made by coagulating soy milk, and then pressing the resulting curds into blocks. The making of tofu from soy milk is similar to the technique of making cheese from milk (Fermentation). Wheat gluten, or seitan, in its steamed and fried forms, is often mistakenly called "tofu" in Asian or vegetarian dishes.

[edit] 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.^[2] The third type of coagulant, enzymes, is not yet used commercially but shows potential for producing both firm and "silken" tofu.

[edit] 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, an important mineral for treating and preventing osteoporosis. As such, many tofu manufacturers choose to use this coagulant to be able to market their tofu as a good source of calcium.

• Chloride-type Nigari salts - 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 Japanese-style 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 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.^[3]

[edit] 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.^[4] Commonly used together with calcium sulfate to give soft tofu a smooth tender texture.

[edit] Enzyme coagulants

• Among enzymes that have been shown to produce tofu are papain, and alkaline and neutral proteinases 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 degrees Celsius.^[3]

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.^[4] 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.^[2]

The curds are processed differently depending on the form of tofu that is being manufactured. For soft silken tofu (嫩豆腐; nèn dòufǔ) 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 (荳乾) or Western types of tofu, are further pressed to remove even more liquid. In Viet Nam, 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, flavoured or further processed.

Although tartness is sometimes desired in dessert tofu, the acid used in flavouring is usually not the primary coagulant since it is not desirable to the flavour 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.

[edit] 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.

[edit] 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 (嫩豆腐 or 滑豆腐, nèn dòufǔ or huá dòufǔ, in Chinese, lit. "soft tofu" or "smooth tofu"; 絹漉し豆腐, kinugoshi tōfu in Japanese, lit. "silk-filtered tofu"; 순두부, sundubu in Korean, lit. "mild tofu"): This undrained tofu contains the highest moisture content of all fresh tofus^[5] Its texture can be described as similar to that of very fine custard. In Korea and Japan, traditional soft tofu is made with seawater. Douhua (豆花, dòu huā or 豆腐花, dòufǔ huā in Chinese), or tofu brain (豆腐腦 or 豆腐脑, dòufǔ 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. 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.
• Asian firm tofu (simply called 豆腐 dòufǔ 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. Can be picked up easily with chopsticks.^[6][5]
• Western firm/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 tofus. 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.^photo[6]

Fresh tofu is usually sold completely immersed in water to maintain its moisture content.^[7]

[edit] 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 flavours.^[8]

[edit] Fermented

• Pickled tofu (豆腐乳 in Chinese, pinyin: dòufǔ 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.^[8] 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 dòufǔ rǔ), red yeast rice (cultivated with Monascus purpureus) is added for color.^[9]
• Stinky tofu (臭豆腐 in Chinese, Pinyin: chòu dòufǔ): A soft tofu that has been fermented in a unique vegetable and fish brine.^[8] The blocks of tofu smell strongly of certain pungent cheeses, and are described by many as rotten and fecal. Despite its strong odour, the flavour and mouthfeel 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.

[edit] Flavoured

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

Flavours 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 dòufǔ in Chinese and jimami-dōfu in Japanese), almond tofu (杏仁豆腐, xìngrén dòufǔ in Chinese; 杏仁豆腐, annindōfu in Japanese), mango tofu, and coconut tofu. In order to produce these forms of tofu, sugar, fruit acids, and flavourants 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 made from tofu but are instead gelatinous desserts made from agar or gelatin and whitened with milk or coconut milk. In Japan these are canned with syrup and sold as a sweet dessert.

Japanese Tofu/ Egg Tofu (玉子豆腐)

• Savoury: Egg tofu (蛋豆腐; dàn dòufǔ, in Chinese) (玉子豆腐; yùzǐ dòufǔ; lit. "jade tofu," in Chinese; 玉子豆腐; tamagodōfu, in Japanese) is the main type of savoury flavoured tofu. Whole beaten eggs are filtered and incorporated into the soy milk before the coagulant is added. The mixture is filled into tube shaped plastic bags 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 flavour than silken tofu, which can be attributed to the presence of egg fat and protein.

[edit] 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 in Chinese, dòupào, lit. "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 dòufǔ, lit. "fried tofu"). These may be eaten by themselves 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.

[edit] Frozen

Thawed and sliced frozen tofu

• Thousand layer tofu (千葉豆腐, 凍豆腐 or 冰豆腐 in Chinese, lit. "thousand layer tofu" or "frozen tofu"): By freezing tofu, the large ice crystals that develop within the tofu results 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 regional specialty in parts of Taiwan. This tofu is defrosted and sometimes squeezed of moisture prior to use.^[7]
• Japanese freeze-dried tofu (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 excellent for camping, in that it is very light, may be sold flattened, and makes a very filling nutritious meal on the road. Like many freeze-dried foods, it is soaked in hot water or broth before eating, taking on a spongy texture when reconstituted. Freeze-dried tofu is also found in instant soups (such as miso soup), in which the toppings are freeze-dried and stored in sealed pouches.

[edit] 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 is called okara.

[edit] Yuba

Boiling of soy milk, in an open shallow pan , produces a film or skin composed primarily of a soy protein-lipid complex on the liquid surface.^[7] The films are collected and dried into yellowish sheets known as yuba or 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. ^[10]

The yuba can also be bunched up to stick form and dried into something known as "tofu bamboo" (腐竹, fǔ zhú in Chinese; phù chúc in Vietnamese; kusatake, Japanese), or a myriad of 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 vegetarian cuisine.

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

[edit] Okara

Okara (雪花菜, xuě huā caì, lit. "snowflake vegetable"; 豆腐渣, dòufǔ zhā, lit. "tofu sediment/residue"; kongbiji, 콩비지 in Korean), sometimes known in the west as soy pulp, is the fibre, protein, and starch left over when soy milk has been extracted from ground soaked soybeans.^[7] 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. Okara is rarely seen or used in Chinese cuisine.

[edit] Tofu made from other legumes and grains

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

• Black bean tofu (黑豆花): A type of tofu made from plain black beans and soybeans, which is usually made into dòuhuā (豆花) rather than firm or dry tofu. The texture of black bean tofu is slighty more gelatinous than regular tofu flower and the color is greyish in tone. This type of tofu is eaten for the earthy "black bean taste."
• Burmese tofu (to hpu in Burmese): A type of tofu made from besan (chana dal) flour instead of soybeans; 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.^{Burmese tofu recipe}

To hpu may be fried as fritters cut in rectangular or triangular shapes; the latter fried twice, hence the name hnapyan gyaw (literally "twice fried"), is the common form in the Shan States. To hpu nway, creamy and soft before it sets, is also popular served hot on its own or with rice noodles. To hpu gyauk, which are deep fried, thin, and crispy, are similar to prawn or fish crackers.

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.

To hpu gyaw (Burmese tofu fritters)

To hpu nway (warm Burmese tofu) and to hpu gyaw (Burmese tofu fritters) salad

To hpu gyauk (Burmese tofu crackers, ready for deep frying)

Hsan ta hpo (Burmese rice tofu) salad

[edit] Preparation

Tofu has very little flavour or smell on its own. As such, tofu can be prepared either in savoury or sweet dishes, acting as a canvas for presenting the flavours of the other ingredients used.

[edit] 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.

[edit] Lightly flavoured

The light greenish "bean" smell of tofu is much enjoyed in East Asian cuisines and fresh tofu is often eaten plain or simply flavoured.

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 flavoured 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.^[11]

In Korean cuisine, dubu jorim consists of cubes of firm tofu that are pan fried and seasoned with soy sauce, garlic, and other ingredients. Cubes of cold, uncooked tofu seasoned with soy sauce, scallions, and ginger, prepared in a manner similar to the Japanese hiyayakkoare also enjoyed.

In the Philippines, the sweet delicacy taho is made of fresh tofu with brown sugar syrup and sago.

In Vietnam, dòuhuā is pronounced đậu hủ (literally "bean in a jar").^{[citation needed]} 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.

[edit] 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.^[11] 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, 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) .

[edit] Soups, stews, and braised dishes

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 dòufǔ