Tofu (Japanese:豆腐,Hepburn:Tōfu,Korean: 두부;RR: dubu,Chinese:豆腐;pinyin:dòufu) is a food prepared bycoagulatingsoy milk and then pressing the resultingcurds into solid white blocks of varying softness:silken,soft,firm, andextra (or super) firm. Tofu is translated asbean curd in English. Tofu originated in China and has been consumed in the country for over 2,000 years.[1][2] Tofu is a traditional component of manyEast Asian andSoutheast Asian cuisines;[3] in modern Western cooking, it is often used as ameat substitute.
Cultivation of tofu, as a protein-rich food source, has one of the lowest needs for land use (1.3 m²/ 1000 kcal)[4] and emits some of the lowest amount of greenhouse gas emissions (1.6 kgCO2/ 100 g protein).[5][6]
The earliest documentation of the word in English is in the 1704 translation ofDomingo Fernández Navarrete'sA Collection of Voyages and Travels, that describes how tofu was made.[11] The wordtowfu also appears in a 1770 letter from the English merchantJames Flint toBenjamin Franklin.[12]: 73 The term "bean curd(s)" for tofu has been used in the United States since at least 1840.[13][14]
The most commonly held of the three theories of tofu's origin maintains that tofu was discovered byLiu An (179–122 BC), aHan dynasty prince. While plausible, the paucity of reliable sources for this period makes this difficult to conclusively determine. InChinese history, important inventions were frequently attributed to important leaders and figures of the time.[24] In 1960, a stone mural unearthed from an Eastern Han dynasty tomb provided support for the theory of the Han origin of tofu; however some scholars maintain that tofu during the Han dynasty was rudimentary and lacked the firmness and taste for it to be considered as tofu.[25]
Another theory suggests that the production method for tofu was discovered accidentally when a slurry of boiled, ground soybeans was mixed with impuresea salt. Such sea salt would probably have contained calcium and magnesium salts, allowing the soy mixture to curdle and produce a tofu-like gel.
The last group of theories maintains that the ancient Chinese learned the method for curdling soy milk by emulating the milk curdling techniques of theMongolians. The primary evidence for this theory is the etymological similarity between the Chinese termrǔfǔ (乳腐), which literally means "milk curdled", used duringSui dynasty (AD 581–618), for dishes with a consistency like yogurt or soft cheese, later influenced by Mongolian milk products and methods of production, and the termdòufu (豆腐, "beans curdled" ) or tofu. Although intriguing and possible, there is no evidence to substantiate this theory beyond academic speculation.[24]
A form of tofu may have been discovered during theHan dynasty (202 BC – AD 220), but it did not become a popular food in China until theSong dynasty (960–1279).[10]
In China, tofu was traditionally eaten at the graves of deceased relatives. Ghosts were said to have long since lost their chins and jaws, so only tofu was soft enough for them to eat. Before the advent of refrigeration in China, tofu was usually sold only in the winter because it did not spoil easily in cold weather. In the warmer months, once made, tofu would spoil if left for more than a day.
Illustration of a tofu seller (right) and asōmen seller (left) byTosa Mitsunobu, from theSongs of the Seventy-one Craftsmen (七十一番職人歌合Shichijūichi-ban ShokuninUta-awase), a poetry anthology written around 1500
Tofu was introduced toJapan by Zen Buddhist monks, who initially called it "Chinese curd" (唐符,tōfu).[10] The earliest Japanese document concerning tofu refers to the dish being served as an offering at theKasuga Shrine inNara in 1183.[26][27]
The tofu that was introduced from China is thought to have originally been hard tofu such as island tofu from Okinawa, hard tofu from Hakusan City in Ishikawa Prefecture, Gokayama City in Toyama Prefecture, and Iya region in Tokushima Prefecture.[28] A firm variation of tofu was introduced inTosa Province, today'sKochi Prefecture, by Mr. Park, the lord of Akizuki Castle and prisoner of war following theJapanese invasions of Korea (1592–1598) and he was given a town and generous protection, and his family and subordinates ran many hard tofu shops and had a monopoly on them.[29][30][31] Gradually, production methods were devised to produce smooth tofu with a pleasant texture, and modern silken tofu was born.[32] The bookTofu Hyakuchin (豆腐百珍), published in 1782 of theEdo period, lists 100 recipes for cooking tofu.[33]
In Southeast Asia, tofu was introduced to the region by Chinese immigrants fromFujian province, as evidenced by many countries in Southeast Asia referring to tofu using theMin Nan Chinese word for either soft or firm tofu, or "tāu-hū" or "tāu-goan" respectively. InIndonesia,Malaysia,Singapore,Thailand,Cambodia,Myanmar, thePhilippines andVietnam, tofu is widely available and used in many local dishes.[citation needed]
Tofu is calledtauhu in Malaysia and Singapore. Malaysian and Singaporean Indians use tofu in their cuisine, such as in Indianmee goreng, androjak pasembor.Peranakan cuisine often uses tofu, as in Penang curry noodles andlaksa. Indonesia, Thailand, Malaysia, and the Philippines are major producers of tofu and have plants in many municipalities.
Tofu in thePhilippines is widely eaten as the breakfast snacktahô (soft tofu, fromPhilippine Hokkien 豆腐 "tāu-hū"), or astokwa (dry, firm tofu that is usually fried, fromPhilippine Hokkien 豆干 "tāu-goan"), which is a staple alternative to meat in main meals and in numerous regional dishes. Tofu was introduced to the archipelago in the 10th to 13th centuries bySong dynasty Chinese mariners and merchants, along with many other foods that became staples of the Philippine diet. The use and production of tofu were first limited to urban centers with influential Chinese minorities, such asCebu orTondo, but quickly spread to even remote native villages and islands.[citation needed]
Benjamin Franklin was the first American to mention tofu, in a 1770 letter toJohn Bartram.[12]: 73 [34] Franklin, who encountered it during a trip to London, included a few soybeans and referred to it as "cheese" from China.[35] In 1770, Franklin also corresponded withJames Flint on the subject of how the Chinese converted callivances (soybeans) into tofu. Flint's writing "Towfu" in his letter is the earliest documented use of "tofu" in the English language.[12]: 73 The first tofu company in the United States was established in 1878.[36] In 1908,Li Yuying, a Chinese anarchist and a vegetarian with a French degree in agriculture and biology, opened a soy factory, the Usine de laCaséo-Sojaïne. This was the world's first soy dairy and the first factory in France to manufacture and sell beancurd.[37]
However, tofu was not well known to most Westerners before the middle of the 20th century, when it was popularized in the United States byWilliam Shurtleff andAkiko Aoyagi (The Book of Tofu, 1975).[38]
Regardless of the product or scale of the production, the production of tofu essentially consists of:
The preparation of soy milk
The coagulation of the soy milk to form curds (douhua)
The pressing of the soybean curds to form tofu cakes
It is similar to the production of dairycheese by coagulating the milk of dairy animals to form curds and pressing and aging the curds to form cheese. Typical tofu-making procedures are cleaning, soaking, grinding beans in water, filtering, boiling, coagulation, and pressing.[39] There are also types, such as Japanese raw silken tofu, in which the curds are not pressed.[40]
Coagulation of the protein and oil (emulsion) suspended in boiled soy milk is the most important step in the production of tofu. This process is accomplished with the aid of coagulants. Coagulation depends on complex interactions. There are many variables including the variety and percentage of protein in the soybeans used, slurry cooking temperature, coagulation temperature, and other factors.[41]
Soybean proteins are mainly composed of 7S and 11S proteins. The negative surface charges on theseglobulins usually cause them to repel each other. Heating soy milk denatures the proteins and exposes hydrophobic groups normally oriented toward the inside of the globulin structure. Cations from coagulants bind the negatively charged groups.[42] As the net charges of the protein molecules are neutralized, attractivehydrophobic interactions dominate over repulsive electrostatic charges, andprotein aggregates are formed.[43]
Two types of coagulants (salts and acids) are used commercially.[44]
Calcium sulfate (gypsum) (Chinese:石膏; pinyin:shígāo) – 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 is tasteless. Also known as gypsum, calcium sulfate is quarried from geological deposits, and no chemical processing or refining is needed, making it the cheapest coagulant used in tofu production. When used in production, the coagulation reaction is slower due to its low solubility, forming a smooth, more gelatinous tofu with relatively high water content and soft texture.[39] Use of this coagulant also makes tofu that is rich incalcium. As such, many tofu manufacturers choose to use this coagulant to be able to market their tofu as a good source of dietary calcium.[citation needed]
Chloride-type nigari salts orlushui (Traditional: 鹵水, 滷水; Simplified: 卤水; Pinyin: lǔshuǐ) –Magnesium chloride andcalcium chloride: Both of these salts are highly soluble in water and affect soy protein in the same way, whereasgypsum is only very slightly soluble in water and acts differently in soy protein precipitation, the basis of tofu formation. These are the coagulants used to make tofu with a smooth and tender texture. In Japan, a white powder callednigari, which consists primarily ofmagnesium chloride, is produced fromseawater after thesodium chloride is removed and the water evaporated. Depending on its production method,nigari/Lushui may also contain small quantities ofmagnesium sulfate (Epsom salt),potassium chloride, calcium chloride, and trace amounts of other naturally occurring salts. Although the termnigari is derived fromnigai, the Japanese word for "bitter", neithernigari nor pure magnesium chloride imparts a perceivable taste to the finished tofu. Calcium chloride is not found in seawater in significant quantities and therefore is not regarded asnigari. It is used extensively in the United States due to its flavor and low cost.[12]: 73 [45] Fresh clean seawater itself can also be used as a coagulant.[46]
Glucono delta-lactone (GDL): A naturally occurring organic acid also used incheesemaking, this coagulant produces a very fine textured tofu that is almost jelly-like. It is used especially for "silken" and softer tofus and confers a faint sour taste to the finished product.[47] GDL is derived from glucose and takes the form of a white powder at room temperature. Its molecular structure contains a six-memberedheterocyclic ring that is hydrolyzed upon contact with water, slowly converting GDL to gluconic acid.[48] When added to soy milk, it gradually lowers the pH and causes proteins to coagulate evenly throughout the mixture,[49] forming a single, smooth gel that is free of air gaps and that resists breaking during transportation. Using GDL as a coagulant, silken tofu can be formed directly in its container, as it does not require pressing.[50] This acid coagulant is also commonly used together with calcium sulfate to give soft tofu a smooth, tender texture.
Other edible acids: Though they can affect the taste of the tofu more, and vary in density and texture, acids such asacetic acid (vinegar) andcitric acid (such as lemon juice), can also be used to coagulate soy milk and produce tofu.[51]
Amongenzymes that have been shown to produce tofu arepapain, and alkaline and neutralproteases from microorganisms. Papain, moreover, has been studied as a gelling agent to produce "instant tofu" from soy protein isolate and soy glycinin (11S) protein.[52][53]
Contemporary tofu manufacturers may choose to use one or more of these coagulants since each plays a role in producing the desired texture in the finished tofu.[47] Different textures result from different pore sizes and other microscopic features in the tofu 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 softgel.[44]
Coagulants are typically added at concentrations between 1.5 and 5.0 g/kg. In all coagulants consisting of calcium or magnesium salts, the positive double-bonded ions of the calcium or magnesium are responsible for the coagulation of the soy proteins which become part of the tofu, thereby enhancing its nutritional value. Only 1 part per 1000 of the tofu eaten is coagulant; most of the coagulant reacts with soy protein and is broken down into ions. The non-reactive portion dissolves in thesoy whey and is discarded.[54]
The curds are processed differently depending on the form of tofu that is being manufactured. For soft silken tofu (嫩豆腐;nèndòufu in Chinese or絹漉し豆腐kinugoshi-dōfu in Japanese) or tofu pudding (豆花,dòuhuā OR 豆腐花,dòufuhuā in Chinese orおぼろ豆腐Oboro-dōfu in Japanese) the soy milk is curdled directly in the tofu's final packaging. For standard firm East Asian tofu, the soy curd is cut and strained of excess liquid usingcheesecloth ormuslin and then lightly pressed to produce a soft cake. Firmer tofus, such as East Asian dry tofu (豆干 in Chinese or凍み豆腐Shimi-dōfu in Japanese) 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 calledđậu khuôn (molded bean) orđậu phụ (one of the Vietnamese ways to pronounce the Chinesedòufu). The tofu curds are allowed to cool and become firm. The finished tofu can then be cut into pieces, flavored or further processed.[citation needed]
Although tartness is sometimes desired in dessert tofu, the acid used in flavoring is usually not the primary coagulant, since concentrations sufficiently high to induce coagulation negatively affect the flavor or texture of the resulting tofu. A sour taste in tofu and a slight cloudiness in its storing liquid is also usually an indication of bacterial growth and, hence, spoilage.
The whiteness of tofu is ultimately determined by the soybean variety, soybean protein composition, and degree of aggregation of the tofu gel network. The yellowish-beige color of soybeans is due to the color compounds including anthocyanin, isoflavones, and polyphenol compounds; therefore the soybean variety used will predicate the color of the final tofu product.[55] Ways to reduce the yellow color include reducing isoflavone content by changing the pH of the soy milk solution used in the production of the tofu so that the relevant compounds precipitate out and are removed during the extraction of okara.[56] The opacity of tofu gel and the off-white color typical of standard uncooked firm tofu is due to the scattering of light by the colloidal particles of the tofu. The addition of higher levels of calcium salts or a high protein content will contribute to forming a denser and more aggregated gel network which disperses more light, resulting in tofu with a whiter appearance.[57]
Tofu flavor is generally described as bland, which is the taste desired by customers in North America. A more beany flavor is preferred in East Asia. The beany or bland taste is generated during the grinding and cooking process, and either a "hot grind" or a "cold grind" can be used to influence the taste. The hot grind method reduces the beany flavor by inactivating thelipoxygenase enzyme in the soy protein that is known to generate off flavors. Eliminating these flavors makes tofu that is "bland". If a cold grind is used lipoxygenase remains and produces the aldehyde, alcohol, and ester volatile compounds that create beany notes.[54]
A wide variety of types and flavors of tofu is available in both Western and Eastern markets. Despite the range of options, 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 by-products that are used in various cuisines.
Unpressed fresh tofu is gelled soy milk with curd that has not been cut and pressed of its liquid. Depending on whether the soy milk is gelled withbittern (magnesium chloride) solution or a suspension of gypsum (calcium sulphate), different types of unpressed tofu are produced. Gypsum-gelled soft tofu has a smooth and gel-like texture and is commonly known as soft tofu, silken-tofu, ordouhua (豆花). The bittern-gelled variety has a very soft spongy curdled texture and is known as extra-soft orsun-dubu (순두부).
Unpressed tofu is so soft that it is directly ladled out for serving or sold with its gelling container.
Unpressedbittern-gelled soft tofu is calledsun-dubu (순두부; "mild tofu") inKorean. Soy milk is mixed withseawater,[58][59][60][61][62] orsaline water made withsea salt, so that it curdles.[63][64] The curds remain loose and soft. Freshly madesun-dubu is eaten boiled with little or no seasoning. Manufacturedsundubu is usually sold in tubes. It is also the main ingredient insundubu-jjigae (순두부찌개; "soft tofu stew").
Although the wordsun insun-dubu does not have aSino-Korean origin,[65]sun-dubu is often translated into Chinese and Japanese using the Chinese character純, whose Korean pronunciation issun and the meaning is "pure". Thus in China,sun-dubu is calledchún dòufu (純豆腐; "pure tofu"), and in Japan, it is calledjun-tōfu (純豆腐) orsundubu (スンドゥブ).
Soft tofu, also known as "silken tofu", is callednèndòufu (嫩豆腐; "soft tofu") orhuádòufu (滑豆腐, "smooth tofu") inChinese;kinugoshi-dōfu (絹漉し豆腐; "silk-filtered tofu") inJapanese; andyeon-dubu (Korean: 연두부;Hanja: 軟豆腐; "soft tofu") inKorean. Gelled with gypsum, this tofu is undrained, and unpressed, and contains a high moisture content.[54] Silken tofu is produced by coagulatingsoy milk without cutting the curd.[66][67] Silken tofu is available in several consistencies, including soft and firm, but all silken tofu is more delicate than regularfirm tofu (pressed tofu) and it has different culinary uses.[68] Silken tofu can be used as a substitute for dairy products and eggs, especially forsmoothies and baked desserts.[69]
Douhua (豆花, also known as豆腐花,dòufuhuā in Chinese), ortofu brain (豆腐腦 or豆腐脑,dòufunǎo in Chinese) ordau fa (Cantonese) andtau hua (Fujianese) (豆花; "bean flower") is similar to silken tofu, but is typically served a few hours after it is prepared. It is most often eaten as a hot dessert, but sometimes salty pickles or hot sauce are added. This is a type of soft tofu with very high moisture content. Because usingchopsticks makedouhua difficult to pick up, it is generally eaten with a spoon. With the addition of flavorings such as finely choppedspring onions, driedshrimp,soy sauce, orchilli sauce,douhua is a popular breakfast dish across China. In Malaysia,douhua is usually served warm with white or dark palm sugar syrup, or served cold withlongans. It is frequently served at breakfast or for dessert. It is usually served either with a sweet ginger syrup, or a mushroom gravy calledda lu (打卤). It's normally coagulated at the restaurant into a serving container. Douhua is not always considered a type of tofu, but rather a type of food in its own right.
Some variation exists among soft tofus. Black douhua (黑豆花, hēidòuhuā) is a type of silken tofu made from black soybeans, which is usually made intodòuhuā (豆花) rather than firm or dry tofu. The texture of black bean tofu is slightly more gelatinous than regulardouhua and the color is greyish in tone. This type of tofu is eaten for its earthy "black bean taste".Edamame tofu is a Japanese variety ofkinugoshi tōfu made fromedamame (fresh green soybeans); it is pale green in color and often studded with wholeedamame.
Depending on the amount of water that is extracted from the cut and pressed curds two types of tofu are produced: firm, and extra firm. Fresh tofu is usually sold completely immersed in water to maintain its moisture content and freshness, and to suppress bacterial growth.
Firm tofu (called老豆腐lǎodòufu in Chinese;木綿豆腐,momen-dōfu in Japanese, "cotton tofu";모두부,mo-dubu in Korean): Although drained and pressed, this form of fresh tofu retains a high moisture content. It has the firmness of raw meat and 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 retains the pattern of the muslin used to drain it, and the outside is slightly more resistant to damage than the inside. It can be picked up easily with chopsticks.[24][54]
A very firm type ofmomen-dōfu is eaten in parts of Japan, calledishi-dōfu (石豆腐, "stone tofu") in parts ofIshikawa, oriwa-dōfu (岩豆腐, "rock tofu") inGokayama in theToyama Prefecture and inIya in the prefecture ofTokushima. These types of firm tofu are produced with seawater instead ofnigari (magnesium chloride), or using concentratedsoy milk. Some of them are squeezed using heavy weights to eliminate excess moisture. These products are produced in areas where traveling is inconvenient, such as remote islands, mountain villages, and heavy snowfall areas.
Dòugān (豆干, literally "dry tofu" in Chinese) orsu ji (素鸡, vegetarian chicken) is an extra firm variety of tofu where a large proportion of the liquid has been pressed out.Dòugān contains the least moisture of all fresh tofu, the firmness of fully cooked meat, and a somewhat rubbery feel similar to that ofpaneer. 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 pressing.
Su ji is a more common type of unflavored, extra-firm tofu. It cannot be crumbled and has a more rubbery texture. 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 (豆干絲,dòugānsī in Chinese, or simply干絲,gānsī), which looks like loose cookednoodles, can be served cold, stir-fried, or added to soup, as with Japaneseaburaage.[24][70]
Many forms of processed tofu exist. Some processing techniques probably[citation needed] originate before the days of refrigeration from the need to preserve tofu or to increase its shelf life. Other production techniques are employed to create tofus with different textures and flavors.[71]
Pickled tofu (豆腐乳 in Chinese,pinyin:dòufurǔ, or腐乳 fŭrŭ;chao in Vietnamese), also called "preserved tofu" or "fermented tofu", consists of cubes of dried tofu that have been allowed to fully air-dry under hay and slowly ferment with the help of aerial bacteria.[71] The dry fermented tofu is then soaked in salt water, Chineserice wine, vinegar or mincedchiles, or in a mixture of whole rice, bean paste, and soybeans. In the case of red pickled tofu (紅豆腐乳 in Chinese, Pinyin:hóng dòufurǔ),red yeast rice (cultivated withMonascus purpureus) is added for color.[a] In Japan, pickled tofu with miso paste is calledtofu no misodzuke, and is a traditional preserved food inKumamoto. InOkinawa, pickled and fermented tofu is calledtofuyo (豆腐餻). It is made fromShima-doufu (an Okinawan variety of large and firm tofu). It is fermented and matured with koji mold, red koji mold, andawamori.
Stinky tofu (臭豆腐 in Chinese, Pinyin:chòudòufu) is soft tofu that has been fermented in a vegetable and fish brine.[71] The blocks of tofu have a pungent cheese smell, sometimes resembling rotting food. 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 East Asian tofu from which it is made. The rind that stinky tofu develops when fried is said to be best when especially crisp, and fried stinky tofu is usually served withsoy sauce, sweet sauce, or hot sauce.[citation needed]
Thawed and sliced frozen tofuKoya-dofu after soaking in water
Thousand-layer tofu (千葉豆腐,qiānyè dòufu, literally "thousand-layer tofu", or 凍豆腐dòngdòufu, 冰豆腐bīngdòufu in Chinese, both meaning "frozen tofu") is a frozen tofu. The ice crystals that develop within it result in the formation of large cavities that appear to be layered. Frozen tofu takes on a yellowish hue in the freezing process. Thousand-layer tofu originates in theJiangnan region of China and is commonly made at home from soft tofu. It is also commercially sold as a specialty in Hong Kong, Taiwan, and other areas with Jiangnan emigrants. It is regularly paired withtatsoi as a winter dish. Frozen tofu is defrosted before serving and sometimes pressed to remove moisture prior to use.
During freezing, the ice crystals puncture cell walls and facilitate the release of free and bound water and cause a decrease in total water content in tofu after freezing then thawing. The initial protein-water bonds are irreversibly replaced by protein-protein bonds, which are more elastic and cause a structural change to the gel network and lead to an increase in textural properties such as hardness, springiness, cohesiveness, and gumminess.[72][73]
In Japan, two kinds of freeze-dried tofu are produced. Those are usually rehydrated by being soaked in water prior to consumption. In theirdehydrated state, they do not require refrigeration.
Kori tofu (凍り豆腐, literally "frozen tofu") isfreeze-dried.[74]Koya-dofu (kōya-dōfu, 高野豆腐 in Japanese) is a freeze-dried tofu fromMount Kōya, a center ofJapanese Buddhism famed for itsshōjin ryōri, or traditional Buddhist vegetarian cuisine. It is said that the method ofKoya-dofu was discovered by accident by leaving tofu outdoors in the winter season. It is sold infreeze-dried blocks or cubes in Japanese markets. It is typically simmered indashi,sake ormirin andsoy sauce. Inshōjin ryōri, vegetariankombu dashi, made from seaweed, is used. When prepared in the usual manner, it has a spongy texture and a mildly sweet or savory flavor. The taste and flavor depend on what soup or cooking stock it was simmered in. A similar form of freeze-dried tofu, in smaller pieces, is found in instant soups (such asmiso soup), in which the toppings are freeze-dried and stored in sealed pouches.
Shimidofu (凍み豆腐) is mainly consumed in the Tohoku region. While Koya-dofu is made by shade-drying, shimidofu is made by sun-drying.
Tofu skin is produced when soy milk is boiled in an open, shallow pan, thus producing a film or skin composed primarily of a soy protein-lipid complex on the liquid surface.[75] The films are collected and dried into yellowish sheets known as "soy milk skin" (腐皮,fǔpí 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.[citation needed]
The skin can also be dried into a product known as "tofu bamboo" (腐竹,fǔzhú in Chinese;phù trúc in Vietnamese;kusatake, Japanese), or into many other shapes. Since tofu skin has a soft yet rubbery texture, it can be folded or shaped into different forms and cooked further to imitate meat in vegan cuisine. Some factories dedicate their production to tofu skin and other soy membrane products. Tofu skin is commonly sold in the form of dried leaves or sheets. Other people would put the "tofu bamboo" into congee (a watery rice mixture that is eaten for breakfast) so that the congee becomes more silky and smooth, and gives a whole new texture. Also, soft, fragile skin would be on the congee once it cools down.[citation needed]Tofu skin is cooked with noodles.[76]
Okara, from theJapanese雪花菜(おから) is known as雪花菜xuěhuācài, inChinese, lit. "snowflake vegetable";豆腐渣,dòufuzhā, alsoChinese, lit. "tofu sediment/residue"; and콩비지,kongbiji, inKorean).
Sometimes known in the west as "soy pulp" or "tofu lees",[77]okara is a tofu by-product consisting of the fiber, protein, and starch left over when soy milk has been extracted from ground soaked soybeans.[78] It is often used as animal feed in most tofu-producing cultures, but also has other uses in Japanese and Korean cuisines, such as in the Korean stewkongbijijjigae (콩비지찌개). It is also an ingredient forvegetarian burgers in many Western nations. InJapan, it is used to makeice cream.[79]
The termtofu is used by extension for similarly textured curdled dishes that do not use soy products, such as "almond tofu" (almond jelly),tamago-dōfu [ja] (egg),goma-dōfu [ja] (sesame), or peanut tofu (Chinese落花生豆腐luòhuāshēng dòufu andOkinawanjīmāmi-dōfu [ja]).
Due to their East 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 hardened usingagar orgelatin. Some foods, such as Burmese tofu, are not coagulated from the "milk" of the legume but rather set in a manner similar to softpolenta,Korean muk, or thejidou liangfen ofYunnan province ofsouthwest China.
"Almond tofu" (Chinese:杏仁豆腐xìngrén dòufu; Japanese:annindōfu) is a milky white and gelatinous substance resembling tofu, but it does not use soy products or soy milk and is hardened withagar. A similar dessert made withcoconut milk ormango juices may occasionally be referred to as "coconut tofu" or "mango tofu", although such names are also given to hot dishes that use soy tofu and coconut or mango in the recipe.
Burmese tofu (to hpu inBurmese) is a legume product made frombesan (chana dal) flour; theShan variety usesyellow split pea flour instead. Both types are yellow in color and generally found only inMyanmar, though theBurman variety is also available in some overseas restaurants servingBurmese cuisine.[80] Burmese tofu may be fried as fritters cut into rectangular or triangular shapes.
A variety calledhsan to hpu (orhsan ta hpo in Shan regions) is made from rice flour (calledhsan hmont ormont 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.
Egg tofu [ja] (Japanese:玉子豆腐,卵豆腐, tamagodōfu) (Chinese:蛋豆腐, dàndòufu; often called日本豆腐, Rìbĕn dòufu, lit. "Japan bean curd") is the main type of savory flavored tofu. Whole beaten eggs are combined withdashi, poured into molds, and cooked in a steamer (cf.chawanmushi). This tofu has a pale golden color that can be attributed to the addition of eggs and, occasionally, food coloring. This tofu has a fuller texture and flavor than silken tofu, due to the presence of egg fat and proteins. Plain "dried tofu" can be flavored by stewing in soy sauce (滷) to make soy-sauce tofu. It is common to see tofu sold from hot food stalls in this soy-sauce stewed form. Today Egg "Japanese" tofu is made of eggs, water, vegetable protein, and seasoning.[81]
Egg tofu was invented in Japan during the Edo period. The book《万宝料理秘密箱》written in 1785 recorded how to make Japanese tofu. Later the Japanese form of tofu entered Southeast Asia, being introduced to China in 1995 from Malaysia.[82][citation needed]
100 grams of Egg tofu has 17 mg calcium, 24 mg magnesium, and 5 grams protein while 100 grams tofu has 138 mg calcium, 63 mg magnesium and 12.2 grams protein. Compared with tofu, Japanese tofu's nutritional value is lower.[citation needed]
Tofu dishes common in Japan include three delicacies (三鲜) Japanese tofu; shrimp Japanese tofu; Japanese tofu in ketchup;teppanyaki Japanese tofu; and Japanese fish-flavored tofu.[citation needed]
In Okinawa, Japan,jīmāmi-dōfu [ja] a peanut milk, made by crushing raw peanuts, adding water and straining, is combined with starch (usuallysweet potato, known locally asumukuji orumukashi (芋澱粉)) and heated until curdling occurs.
The tofu known asgoma-dōfu [ja] is made by grindingsesame into a smooth paste, combining it with liquid andkudzu starch, and heating it until curdling occurs. It is often served chilled ashiyayakko.
Tofu has very little flavor or smell of its own. Consequently, tofu can be used in both savory and sweet dishes, acting as a bland background for presenting the flavors of the other ingredients used. In order to flavor the tofu it is often marinated in soy sauce, chillis, sesame oil, etc.
In East Asian cooking, tofu is prepared in many 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.
With the exception of the softest tofus, all forms of tofu can be fried. Thin and soft varieties of tofu aredeep fried in oil until they are light and airy in their core 豆泡dòupào, 豆腐泡dòufupào, 油豆腐yóudòufu, or 豆卜dòubǔ in Chinese, literally "bean bubble", describing the shape of the fried tofu as a bubble.
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 puff up like aplain doughnut. The former is usually eaten plain in Chinese cuisine with garlic soy sauce, while the latter is either stuffed withfish paste to makeYong Tau Foo or cooked in soups.[83] InTaiwan, fried tofu is made into a dish called "A-gei", which consists of a fried aburage tofu package stuffed with noodles and capped withsurimi.
Tofus such as firm East Asian anddòugān (Chinese 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,zhádòufu, 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 calledluohan zhai.
A spicySichuan preparation using firm East Asian tofu ismápó dòufu (麻婆豆腐). It involves braised tofu in abeef, chili, and fermented bean paste sauce. A vegetarian version is known asmálà dòufu (麻辣豆腐).[citation needed]
Dried tofu is usually not eaten raw but first stewed in a mixture of soy sauce and spices.[citation needed] 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wǔxiāng dòufu) or "soy sauce stewed tofu" (鹵水豆腐lǔshuǐ dòufu). Dried tofu is typically served thinly sliced with choppedgreen onions or with slices of meat for added flavor.[83]
Tofu bamboos are often used inlamb stew or in adessertsoup. Tofu skins are often used as wrappers indim sum.[citation needed] 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 them can provide protein for many days.[citation needed]
Pickled tofu is commonly used in small amounts together with its soaking liquid to flavor stir-fried or braisedvegetable dishes (particularlyleafy green vegetables such aswater spinach). It is often eaten directly as acondiment with rice orcongee.
InJapan, a common lunch in the summer months ishiyayakko (冷奴), silken or firm East Asian tofu served with freshly gratedginger,green onions, orkatsuobushi shavings withsoy sauce. In the winter, tofu is frequently eaten asyudofu, which is simmered in a clay pot inkombudashi, with vegetables such asChinese cabbage or green onion.
Deep fried tofu is calledatsuage (厚揚げ) ornamaage (生揚げ) in Japan. The thinner variety calledaburaage (油揚げ), develops a tofu pouch often used forinarizushi.
In Japan, cubes of lightly coated and fried tofu topped with akombudashi-based sauce are calledagedashi dōfu (揚げ出し豆腐). Soft tofu that has been thinly sliced and deep fried, known asaburage in Japan, is commonlyblanched, seasoned withsoy sauce andmirin and served in dishes such askitsuneudon.
InGifu Prefecture, there is a local specialty calledkomo-dofu, which consists of tofu that has been wrapped in akomo, or mat of woven straw, which leaves its imprint on the exterior. The wrapped tofu is then boiled in soup stock. Voids within the tofu develop during the boiling process, allowing the soup stock flavor to penetrate and giving it a distinctive porous appearance.[84][85]
Soft tofu can also be broken up or mashed and mixed with raw ingredients prior to being cooked. For example, Japaneseganmodoki is a mixture of chopped vegetables and mashed tofu. The mixture is bound together with starch and deep-fried. Chinese families sometimes make a steamedmeatloaf ormeatball dish from equal parts of coarsely mashed tofu and ground pork.[citation needed]
Dubu plays an important part inKorean cuisine.[86] Tofu is often pan-fried and served asbanchan with a dipping sauce.[87] It is also used in many soups. Cubes of firm tofu can be seasoned with soy sauce, garlic, and other ingredients before pan-frying. A dish of tofu cubes simmered with similar spicy seasoning is calleddubu-jorim.[88]Dubu-kimchi features blanched tofu served in rectangular slices around the edges of a plate with pan-friedkimchi. This is a popular food to accompany alcoholic drinks (anju).[89] Soft, unpressedsun-dubu is used as the main ingredient ofsundubu-jjigae (soft tofu stew),[90] while other soups and stews such asdoenjang-guk (soybean paste soup),doenjang-jjigae (soybean paste stew), andkimchi-jjigae (kimchi stew) tend to have diced firm tofu in them. As in many other East Asian countries, tofu is also enjoyed in a hot pot dish calleddubu-jeongol (tofu hot pot).
Pan-fried tofu served with seasonedsoy sauce for dipping
InIndonesia, tofu is calledtahu, a loanword from theHokkien Chinese pronunciation of tofu (tāu-hū, 豆腐). In Indonesian markets, tofu is usually available in two forms:tahu putih or common white firm tofu; andtahu goreng or fried tofu that has developed a brown skin.Tahu yun yi ortahu Bandung is yellow tofu colored withturmeric.
A common cooking technique in many parts of East and Southeast Asia involves deep frying tofu invegetable oil,sunflower oil, orcanola oil. In Indonesia, it is usually fried inpalm oil. Although pre-fried tofu is often sold cold, it is seldom eaten directly and requires additional cooking.
Popular Indonesian tofu dishes includetahu gejrot andkupat tahu.Tahu gejrot istahu pong type of hollow fried tofu cut into small pieces, served with a thin, watery dressing made by blendingpalm sugar, vinegar, andsweet soy sauce, garnished with chili pepper, garlic, and shallot.Kupat tahu is slices of tofu served withketupat rice cake, usually in peanut sauce dressing. Slices of tofu are usually mixed ingado-gado,ketoprak andsiomay.
Bacem is a method of cooking tofu originating inCentral Java. The tofu is boiled in coconut water, mixed withlengkuas (galangal), Indonesian bay leaves,coriander,shallot,garlic,tamarind andpalm sugar. After the spicy coconut water has completely evaporated, the tofu is fried until it is golden brown. The result is moist but rather firm, sweet, and spicy tofu. This cooked tofu variant is commonly known astahu bacem inIndonesian.Tahu bacem is commonly prepared along withtempeh and chicken.
In thePhilippines, the sweet delicacytaho is made of fresh tofu with brown sugar syrup andsago. The Malaysian and Singaporean version oftaho ordouhua is calledtofufa ortaufufa. Warm soft tofu is served in slices (created by scooping it from a wooden bucket with a flat spoon) in a bowl with either pandan-flavored sugar syrup or palm sugar syrup.
Generally, the firmer styles of tofu are used forkebabs, mock meats, and dishes requiring a consistency that holds together, while the softer styles can be used for desserts, soups, shakes, and sauces.
Some people enjoy tofu made and prepared with chocolate and making it into pies and mousse along with other tofu desserts.
This came about due to vegans and vegetarians avoiding the usage of items such as milk and eggs.
Firm Western tofu types can be barbecued since they hold together on a barbecue grill. These types are usually marinated overnight as the marinade does not easily penetrate the entire block of tofu. (Techniques to increase the penetration of marinades include stabbing repeatedly with a fork or freezing and thawing prior to marinating.) Grated firm Western tofu is sometimes used in conjunction withtextured vegetable protein (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 aslasagna.[91] Tofu has also been fused into other cuisines in the West, for instance in Indian-style curries.
Tofu is made from soy milk which is aturbidcolloid liquid/solution. Tofu structure is related to soy milk components, particularly colloid components such as protein particles and oil globules. Protein particle content increases with the increase of the globulin ratio in the soybeans. Tofu varieties ensue from addingcoagulants at various concentrations.[95]
The two main components of the soybean important in tofu making are the 11S component, containing glycinin, and the 7S subunit, containing hemagglutinins, lipoxygenases, b-amylase, and β-conglycinin. The major soy protein components, in the two fractions that make up 65–85% of the proteins in soybeans, include glycinin and β-conglycinin. The soybean protein consists of many different subunits, which are sensitive to heat, pH, and ionic strength and become unevenly distributed among soluble and particulate fractions due to hydrophilic and hydrophobic interaction because of the amino acid composition.[12]: 73
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