Tofu (豆è…, tofu?), or bean curd[5] is a soft white food made by coagulating soy milk, and then pressing the resulting curds into blocks. It is of Chinese origin,[6] and part of East Asian and Southeast Asian cuisine such as Chinese, Japanese, Korean, Indonesian, Vietnamese[7] and others.[8] 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 Han dynasty in ancient China,[6] Li Shizhen in Ming Dynasty described the method of making tofu in Bencao Gangmu[9]. Tofu and its production technique were subsequently introduced into Korea, then Japan[10][11][12] during the Nara period, and Taiwan. It also spread into other parts of East Asia as well.[13] This spread likely coincided with the spread of Buddhism as it is an important source of proteins in the vegetarian diet of East Asian Buddhism.[10]
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.
//The English word ``tofu`` comes from the Japanese tÅfu (豆è…), listen (help·info) which itself derives from the Chinese dòufu (è±†è… or è³è…). Although in both languages the characters together translate as ``bean curd,`` the literal meaning of the individual characters is ``bean`` (豆) and ``curdled`` (è…).[14][15]
The English word ``bean curd`` for tofu was coined by Sinologist Emil Bretschneider in 1870. He wrote, ``Bean-curd is one of the most important articles of food in China`` in the Chinese Recorder and Missionary Journal[16].
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.[17] The third type of coagulant, enzymes, is not yet used commercially but shows potential for producing both firm and ``silken`` tofu.
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.[20] 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.[17]
The curds are processed differently depending on the form of tofu that is being manufactured. For soft silken tofu (嫩豆è…; nèn dòufu) or tofu flower (豆花, dòuhuÄ) 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 Ä‘áºu khuôn (molded bean) or Ä‘áºu 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.
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.
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 sliceSoft/silken tofu(å«©è±†è… or 滑豆è…, nèn dòufu or huá dòufu, in Chinese, lit. ``soft tofu`` or ``smooth tofu``; 絹漉ã—豆è…, kinugoshi tÅfu in Japanese, lit. ``silk-filtered tofu``; 순ë‘부, 純豆è…, sundubu in Korean, lit. ``pure tofu``) is undrained tofu that contains the highest moisture content of all fresh tofus.[21] Its texture can be described as similar to that of very fine custard. In Japan and Korea, traditional soft tofu is made with seawater.[22][23][24][25][26]
Douhua (豆花, dòu huÄ or 豆è…花, dòufu huÄ in Chinese), or tofu brain (豆è…è…¦ or 豆è…è„‘, dòufu naÇ’ 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 dòuhuÄ (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 tÅfu made from edamame (fresh green soybeans); it is pale green in color and often studded with whole edamame.
Firm tofu (called è€è±†è… lÇŽo dòufu in Chinese; 木綿豆è…, momendÅfu 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.[21][27]
Dried tofu (豆乾, dòu gÄn 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 gÄn sÄ« in Chinese, or simply 乾絲, gÄn sÄ«), which looks like loose cooked noodles, and can be served cold, stir-fried, or similar in style to Japanese aburaage.[27][28] Fresh tofu is usually sold completely immersed in water to maintain its moisture content.
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.[29]
Flavors can be mixed directly into curdling soy milk while the tofu is being produced.
Sweet: Common sweet dessert tofus include peanut tofu (è½èŠ±ç”Ÿè±†è…, luòhuÄshÄ“ng dòufu in Chinese and jimami-dÅfu in Japanese), almond tofu (æä»è±†è…, xìngrén dòufu in Chinese; æä»è±†è…, annindÅfu 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 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. Savory: Egg tofu (Japanese: 玉å豆è…, åµè±†è…, tamagodÅfu) (Chinese: 蛋豆è…, dà n dòufu; often called 日本豆è…, rìbÄ•n 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 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 flavor than silken tofu, which can be attributed to the presence of egg fat and protein.
