|Traditional Chinese:||荳腐 or 豆腐|
|Literal meaning:||bean curd|
or đậu hũ
or tàu hũ
Tofu, also tōfu (the Japanese Romaji spelling), doufu (the Chinese Pinyin spelling often used in Chinese recipes) or bean curd (the literal translation), is a food of Chinese origin, made by coagulating soy milk, and then pressing the resulting curds into blocks. There are many different varieties of tofu, including fresh tofu, tofu processed or preserved in a variety of ways, and tofu by-products such as tofu skins and soy pulp (Japanese: okara). 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. Some tofu is made by processing non-soy products, such as almonds or black beans.
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Tofu originated in ancient China, but little else is known about the origins of tofu and its method of production. Tofu and its production technique were introduced into Japan in the Nara period (late eighth century), and spread to other parts of East Asia, where it has become a core ingredient of many cuisines. Tofu is low in calories, contains beneficial amounts of iron (especially important for women of child-bearing age) and has no saturated fat or cholesterol. Depending on the coagulant used in manufacturing, the tofu may also be high in calcium (important for bone development and maintenance), and magnesium (especially important for athletes). Tofu also contains soy isoflavones, which can mimic natural human estrogens and may have a variety of harmful or beneficial effects when eaten in sufficient quantities.
The English word "tofu" comes from the Japanese tōfu (豆腐), which derives from the Chinese dòufǔ (豆腐 or 荳腐). Although in both languages the characters together translate as "bean curd," the literal meaning of the individual characters is "bean" (豆) and "curdled" (腐).
Tofu originated in ancient China. There are many theories regarding the origins of tofu, but little historical information to prove or disprove them. It is known that tofu was widely consumed in ancient China, and that techniques for its production and preparation eventually spread to many other parts of Asia.
The most common theory about the origin of tofu origin maintains that it was invented in northern China around 164 B.C.E. by Lord Liu An, a Han Dynasty prince. Chinese folklore often attributes important inventions to well-known historical figures; techniques of tofu production probably existed long before this time.
Another theory is that the method for producing tofu was discovered accidentally when a slurry of boiled, ground soybeans was mixed with impure sea salt, containing calcium and magnesium salts, which caused the soy mixture to curdle and produce a tofu-like gel. Soy milk has been eaten as a savory soup since ancient times.
A third theory 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. Despite their advancement, no technology or knowledge of culturing and processing milk products existed within ancient Chinese society. The primary evidence for this theory lies in the etymological similarity between the Chinese term for Mongolian fermented milk (rufu, which literally means "milk spoiled") and the term doufu or tofu.
Tofu is known to have been a commonly consumed food in China by the second century B.C.E. 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 Dynasties show that the technique for the production of tofu had already been standardized by that time.
In China, tofu is traditionally presented as a food offering when visiting the graves of deceased relatives. According to tradition, tofu is the only food soft enough for the spirits (or ghosts), who have long ago lost their chins and jaws, to eat. Before refrigeration was available in China, tofu was often sold only during the winter time. During the warmer months, leftover tofu would be spoiled if not consumed within a day.
Tofu and its production technique were introduced into Japan in the Nara period (late eighth century) as well as to other parts of East Asia. The earliest documented record of tofu in Japan shows that the dish was served as an offering at the Kasuga Shrine in Nara in 1183. The rise in acceptance of tofu may have coincided with the rise of Buddhism, as tofu is an important source of protein in a vegetarian diet. The book Tofu Hyakuchin (豆腐百珍), published during the Edo period, lists 100 recipes for cooking tofu.
The production of tofu from soy milk is similar to the production of cheese from milk. Tofu is made by coagulating soy milk and pressing the resulting curds. Although commercial soy milk may be used, most tofu producers begin by making their own soy milk, produced by soaking, grinding, boiling, and straining dried (or, less commonly, fresh) soybeans. Some non-soy products, such as almonds or black beans, are also processed to make tofu.
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 for commercial production. A third type of coagulant, enzymes, is not yet used commercially but shows potential for producing both firm and "silken" tofu.
Contemporary tofu manufacturers may use a combination of these coagulants to produce a desired texture in the finished tofu. Different textures result from a difference in pore sizes and other microscopic features in the tofus produced using each coagulant. The coagulant mixture is dissolved in water, and the solution is then stirred into boiled soy milk until the mixture curdles into a soft gel.
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 container in which the tofu will be sold. For standard firm Asian tofu, the soy curd is cut and excess liquid is strained off using cheese cloth or muslin, then the curds are lightly pressed into a soft cake. Firmer tofus, such as Asian dry tofu (荳乾) or Western types of tofu, are 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 for flavoring is typically not the primary coagulant, since a concentration of acid high enough to induce coagulation would produce an unpleasant flavor and texture. A sour taste in tofu and a slight cloudiness in the liquid around are an indication of bacterial growth and spoilage.
Many varieties of tofu are available in both Western and Eastern markets. Tofu products can be categorized either as fresh tofu, which is produced directly from soy milk, or as processed tofu, which is produced from fresh tofu. Tofu production also creates important side products which are used in various cuisines. A byproduct of the process is soy pulp (also called okara in Japanese).
There are three main varieties of fresh tofu, depending on the amount of water that is extracted from the tofu curds:
Fresh tofu is usually sold completely immersed in water to maintain its moisture.
Many forms of processed tofus exist. Some of these processing techniques probably originated 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.
Flavors can be mixed directly into the curdling soy milk while tofu is being produced.
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 solids left over from pressing soy milk are called okara.
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. 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 percent protein, 24–26 percent lipids (fat), 12 percent carbohydrate, 3 percent ash, and 9 percent moisture.
The skin can also be bunched up in stick form and dried into something known as "tofu bamboo" (腐竹, fǔ zhú in Chinese; phù chúc in Vietnamese; kusatake, Japanese). Tofu skin, with its soft yet rubbery texture, is folded or shaped into different forms and cooked further to imitate meat in vegetarian cuisine.
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 fiber, protein, and starch left over when soy milk has been extracted from ground, soaked soybeans. 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.
Tofu has very little flavor or smell of its own and can be prepared either in savory or sweet dishes, acting as a complement to the flavors of the other ingredients used. In Asian cuisine, tofu is served raw, stewed, stir-fried, in soup, cooked in sauce, or stuffed with fillings. The light, greenish "bean" smell of tofu is much enjoyed in East Asian cuisines and fresh tofu is often eaten plain or simply 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, katsuobushi (dried salmon) shavings and soy sauce. In many parts of China, fresh tofu is similarly eaten with soy sauce, century eggs (皮蛋), and sesame seed oil.
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.
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 Japanese hiyayakko, are 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. This variety of soft tofu is made and carried around in an earthenware jar. It is scooped into a bowl with a shallow, flat spoon, and is served with either powdered sugar and lime juice, or with a ginger-flavored syrup. It is generally eaten hot, even during summer.
A common cooking technique in many parts of East and Southeast Asia involves deep frying tofu in vegetable oil, sunflower oil, or canola oil. 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 (surimi) or cooked in soups. 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 soaked in a sweet syrup and cut open to form a pocket; stuffed with sushi rice, this dish is called inarizushi (稲荷寿司) .
A well-known hot Sichuan preparation using firm Asian tofu is mápó dòufu (麻婆豆腐). Tofu and beef are braised in a sauce of chili, ginger and fermented bean paste. In the Shanghai region it is called málà dòufǔ (麻辣豆腐).
Dried tofu is usually not eaten raw, but stewed in a mixture of soy sauce and spices. Some types of dried tofu are pre-seasoned 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 stewed by tofu vendors. 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 journeys; a small bag of dried tofu can provide protein for many days.
In Korean cuisine, soft tofu (sundubu in Korean) is used to make a thick soup called sundubu jjigae (순두부 찌개).
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.
Firm tofu can be 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.
Before grilling, firm tofu is usually marinated overnight. Grated firm western tofu is sometimes used in conjunction with TVP (textured vegetable protein) as a meat substitute. Softer tofus are sometimes used as a dairy-free or low-calorie filler, or made into ice cream substitutes. Silken tofu may be used to replace cheese in certain dishes (such as lasagna) or incorporated into Indian-style curries.
Tofu and soy protein can be industrially processed to match the textures and flavors of cheese, pudding, eggs, or bacon. 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 a source of high-quality, non-animal protein.
Tofu is low in calories, contains beneficial amounts of iron (especially important for women of child bearing age) and has no cholesterol (a risk factor for heart disease). Depending on the coagulant used in manufacturing, the tofu may also be high in calcium (important for bone development and maintenance), and magnesium (especially important for athletes). Tofu is relatively high in protein, about 10.7 percent for firm tofu and 5.3 percent for soft "silken" tofu with about 2 percent and 1 percent fat respectively as a percentage of weight.
Tofu contains soy isoflavones, which can mimic natural human estrogens and may have a variety of beneficial effects when eaten in sufficient quantities. Some health studies have claimed that regular consumption of tofu and soy milk alleviates symptoms of menopause, reduces the risk of osteoporosis, lowers bad cholesterol and helps prevent certain types of cancers. Other studies contradict these claims. 
In the East, tofu may be produced locally by relatively small vendors or distributed nationwide by large manufacturers. 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 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. In Japan, silken tofu without preservatives is made daily and must be sold within two days.
In the West, tofu can be obtained in Asian markets, farmers' markets, and health food stores. Depending on its local popularity, many grocery stores also stock tofu.
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