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Tofu is made by coagulating soy milk and then pressing the resulting curds into soft white blocks. Of Chinese origin, and it is also a part of East Asian and Southeast Asian cuisine such as Japanese, Korean, Indonesian and Vietnamese. 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 it is often seasoned or marinated to suit the dish.
It contains a low amount of calories, relatively large amount of iron, and little fat. Depending on the coagulant used in manufacturing, the tofu may also be high in calcium and/or magnesium. Tofu is relatively high in protein, about 10.7% for firm tofu and 5.3% for soft "silken" tofu with about 5% and 2% fat, respectively as a percentage of weight. In the Western cuisine, it is associated with vegetarianism and veganism.
The history
The English word "tofu" comes from the Japanese tōfu (豆腐), which itself derives from the Chinese dòufu (豆腐 or 荳腐) from "bean" (豆) plus "curdled" or "fermented" (腐).
Tofu originated in the Han dynasty in ancient China, and its production technique were subsequently introduced into Korea and then Japan during the Nara period and spread into other parts of East Asia. This spread likely coincided with the spread of Buddhism because it is an important source of protein in the vegetarian diet of East Asian Buddhism.
How to
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. The third type of coagulant, enzymes, is not yet used commercially but shows potential for producing both firm and "silken" tofu.
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 dòufu). 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.
- 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.[20] Its texture can be described as similar to that of very fine custard. In Japan and Korea, traditional soft tofu is made with seawater.
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 served warm with white or dark (palm) sugar water, or served cold 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.
- Dried tofu
Dried tofu (豆乾, dòu gān in Chinese, lit. "dry tofu"): Despite its name the tofu has not actually been dried but is rather an extra firm variety of tofu with a large amount of liquids pressed out of it. It contains the least amount of moisture of all fresh tofu and 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, can be served cold, stir-fried, or similar in style to Japanese aburaage. Fresh tofu is usually sold completely immersed in water to maintain its moisture content.
Processed tofu
There are many forms, 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.
- Fermented
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. 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. And in Japan, pickled tofu with miso paste is called 'tofu no misoduke', which is traditional preserving food in Kyushu,especially in Kumamoto.
Stinky tofu (臭豆腐 in Chinese, Pinyin: chòu dòufu): A soft tofu that has been fermented in a unique vegetable and fish brine. 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
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.
Frozen
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. 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 pressed to remove 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.
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.
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.
In Japan, a common lunch in the summer months is hiyayakko (冷奴), silken or firm Asian tofu served with freshly grated ginger, green onions, and/or katsuobushi shavings with soy sauce. In the winter, tofu is frequently eaten as yudofu, which is simmered in a claypot with some vegetables (ex:Chinese cabbage, green onion etc.) using konbudashi.
Dòuhuā (豆花), is a soft tofu dish, prepared in Lamma Island or Hong Kong. The fresh tofu is served warm and here dressed with sweet syrup. In the 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. And also,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.
In the Korean cuisine, dubu gui (두부구이) 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.
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. 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)
Bacem is a method of cooking tofu originating from Java, Indonesia. The tofu is boiled in coconut water, mixed with lengkuas (galangal), Indonesian bay leaves, coriander, shallot, garlic, tamarind and palm sugar. After the spicy coconut water has completely evaporated, the tofu is fried until it is golden brown. The result is sweet, spicy, and crisp.
This cooked tofu variant is commonly known as tahu bacem in Indonesian. Tahu bacem is commonly prepared along with tempeh and chicken.
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.
In the Western European cuisine, 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. 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 non-animal protein.
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