History of Fermented Tofu (to Nov. 1985) - Page 1

by William Shurtleff and Akiko Aoyagi

A Chapter from the Unpublished Manuscript, History of Soybeans and
Soyfoods, 1100 B.C. to the 1980s

©Copyright 2004 Soyfoods Center, Lafayette, Californi

For updated and greatly expanded free information on this subject, on our website go to "Historical Bibliographies and Sourcebooks on Soy," then click on the corresponding subject. A lengthy digital book will appear in PDF format. It is searchable using Adobe Acrobat or Adobe Reader .

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All fermented tofu products can be divided into two basic types: traditional Chinese-style products, which we call "fermented tofu," and modern Western cheeselike products, which we call "fermented tofu cheeses," and which have never been commercialized. The former are described in the next few paragraphs. The latter are generally made like Western-style cheeses, without inoculating small cubes of tofu with a mold and without immersing in a brining liquor.


There are many different varieties of Chinese-style fermented tofu, as described below. The most popular type typically consists of cubes of mold-fermented tofu having an pale yellow color, a soft (almost creamy) consistency, plus a pronounced flavor and aroma reminiscent of Camembert cheese, with a hint of anchovy flavor. Often sold floating or immersed in a brining liquor, it is typically used in small amounts as an aromatic seasoning.

To make this most popular type, wine-fermented tofu, very firmly pressed tofu is cut into pieces about 1 inch square and 3/4 inch thick, inoculated with spores of a mold ( Actinomucor elegans, Mucor racemosus , or Rhizopus species), then incubated for about 3 days at 20°C (68°F) until each cube is covered with a cottony-white mycelium. The freshly molded cubes are then placed in crocks or bottles with a mixture of rice wine, salt, walter,and often spices, such as red chilies. After 2-6 months, the product is ready to use. Longer aging generally produces a better product.

Basic Types of Fermented Tofu . The many kinds of fermented tofu may be divided into two basic types and ?? varieties, depending on the nature of the fermentation process.

I. Tofu Molded Before Pickling

1. Molded Tofu Fermented in Brining Liquor . The basic process for making this type of fermented tofu is the one described above. The following may be added to the brining liquor to flavor and/or color the tofu: red chilies, sesame oil, soy sauce, five-spice powder, etc. This is by far the most widely used tofu fermentation process (Wai 1968). Note that the process involves two ripening techniques: first, a mold ripening, as done on popular mold-ripened dairy cheeses such as Roquefort and Camembert, and then a brine ripening, as done on a few less well known cheeses such as Feta, Iranian white cheese, and Indian panir. No Western dairy cheese combines both the mold and the brine ripening.

2. Molded Tofu Fermented with Brine or Salt. Prepared without wine or any alcohol, molded tofu cubes are fermented in a brine or packed in salt.

3. Molded Tofu Fermented With Red or White Koji. This process is basically the same as that described above except that rice koji is added as a second source of enzymes (and often of flavor and color too), and much less liquid is used in the brining mash or dressing. The koji may be added either in the form of red koji (see below), plain rice koji, or koji fermented in water for several days to form a thick, rather sweet, mildly alcoholic, and delicious grog called chiu niang in China and amazake or doboroku in Japan (Shih 1918). Or the koji may consist of a Mucor or Aspergillus mold grown on wheat flour (Smith 1949).

A word about red koji : Also known in the literature as beni koji (Japanese), hung chu (Chinese), angkak (ankak, anka, ang quac), ang-tsao, red rice, or Chinese red rice, this product originated in China. It is prepared by soaking rice in water for 24 hours, steaming, cooling, inoculating with spores of the mold Monascus purpureus , and allowing to ferment at a warm ambient temperature (27°C or 81°F is ideal) for about 20 days. Mixed with water, brine, or alcohol and used as a pickling medium for tofu, it imparts a rich red color and unique flavor. In the Philippines it is also used in making a fermented fish called Burong isda (Asean 1980).

4. Molded Tofu Fermented in Rice Wine or its Lees. Prepared without salt, molded tofu cubes are fermented quickly (12 hours or more) in rice wine (often unrefined; shirozake or doboroku ) and/or its lees ( chu-tsao ). In some areas, crushed leaves, cloves, orange peels, and tofu whey may be added, and a green Mucor mold used. The best known variety is chou doufu ("redolent fermented tofu").

5. Molded Tofu Pickled in Miso or Soy Sauce Moromi. Pieces of molded, very firm tofu are sprinkled with salt then immersed in miso or soy sauce moromi (Nakazawa 1967).

6. Molded Tofu Pickled in Red Koji and Miso or Soy Sauce Moromi. Same as the above, except that red koji (angkak) is part of the dressing. (Nakazawa 1967).

7. Quick Molded Tofu Sheets without Salt. In the Philippines, fresh and unsalted pressed tofu sheets, made as described above, are allowed to stand until they mold; this imparts a meatlike flavor. The sheets are then fried in sesame oil and served in place of meat (Orosa 1932).

II. Tofu Not Molded Before Pickling

1. Tofu Pickled in Miso or Soy Sauce Moromi. Very firm tofu, well drained, is sprinkled with salt then immersed in miso or soy sauce moromi (Nakazawa 1967).

2. Dried Tofu Fermented with Millet Brandy Plus Red and White Koji. Made in Okinawa and called tofu-yo , it is prepared by cutting very firm, dried tofu into cubes and immersing these in ground red and white koji, which have been softened by soaking in awamori (millet brandy) for 2-3 days. After addng a little salt, the tofu is fermented for 3-6 months (Yasuda et al. 1983, 1984; NHK 1985a,b).

3. Firm Tofu Fermented with Wheat Koji and Brining Liquor. The koji is made by mixing wheat flour with water, boiling this, breaking it into small pieces, allowing it to mold for about 1 week to make a wheat-flour koji, sun-drying for 2 days, then grinding to form a powdered koji called jiang hsi ?? in Chinese. This is then combined in an earthenware crock with firm tofu, salt, rice wine, soy sauce, water, sugar, and red koji. Shih (1918) called the finished product chiang fu-yu or chiang ju-fu . (What is it called today in pinyin??)

4. Firm Tofu and Wine Fermentation. Prepared without salt, fresh tofu cubes are fermented quickly (12 hours or more) in rice wine and its lees ( chu-tsao ). In some areas, crushed leaves, cloves, orange peels, and tofu whey may be added, and a green Mucor mold used. The best known variety is chou doufu ("redolent fermented tofu").

5. Tofu Fermented with Brine or Salt. Prepared without wine or any alcohol, fresh or molded tofu cubes are fermented in a brine or packed in salt.

6. Tofu Fermented with Salt and Koji. Very firm, drained tofu is sprinkled with salt then pickled in moistened koji (Nakazawa 1967).

7. Pressed Tofu Sheets and Salt Fermentation. Tofu is pressed between layers of cloth into thin sheets that look like heavy canvas. These are rolled into thin rolls, sprinkled with salt, and packed into a covered bowl to ferment naturally for a few days to yield a strong-flavored product known as mei chien chiang or, in pinyin mei ?? qiangzhang ("fermented thousand sheets") which is steamed and served. This fermented tofu is made at home in some parts of China. No mention is made of the use of a mold (Wang et al. 1977, 1979; Ng 1979).

Etymology . The earliest known Chinese reference to fermented tofu appeared in the famous herbal Pen-ts'ao kang-mu , written by Li Shih-chen in 1578. The the product was called rufu ?? ("milk spoiled"). Today it is known by a bewildering array of names, in both because of the numerous regional dialects in China and because of the difficulties and inconsistencies in transcribing Chinese into English.

Since 1979, in standard pinyin, fermented tofu has been called doufuru (pronounced doe-fu-RU). Prior to 1979 the Wade Giles system transcribed this term from standard Mandarin into English as toufu-ru or toufu-ju , or in abbreviated form as furu , fuju or fulu . Interestingly the two characters pronounced furu can also be written in reverse order as rufu , pronounced "RU-fu." In the Cantonese of south China it is known as fuyu, toufu-yu, fuju, or funan ; in the Shanghai or Nanjing dialects as sufu or tou-sufu , in Hong Kong as fusu ; and in Taiwan as tauhu-yi or tau-zu (Su 1977; L-P. Lin 1977). Around Beijing, in addition to the standard doufuru , one also hears furu, rufu , and dou-ru .

The three characters in the standard pinyin word for fermented tofu, dou-fu-ru, mean "bean spoiled milk." They have an unusual origin. Although the Chinese had one of the world's earliest civilizations, they never developed the practice of dairying and, hence, of making cheese or other dairy products, as explained in Chapter 33, Soymilk. But their northerly nomadic neighbors, the Mongols, whom the Chinese regarded as barbarians, were skilled in making fine goat cheese. The Chinese derogatorily called this cheese furu or "spoiled milk." Centuries later, when the Chinese learned how to make a similar fine cheese from soymilk or tofu, the term they had once used disparagingly boomeranged; it came to refer to their own product and remains with them to this day. In the Shanghai dialectical term sufu , the su can be written with any of three characters, meaning respectively "molded or cheese," "vinegar" or "butter." The character fu , meaning "spoiled," is also the second character in "tofu" (Nakano 1979).

An unusual, in fact notorious, type of chinese fermented tofu is chou doufu . The character chou means "stinking" or "foul smelling;" hence, in English it is often called "stinking tofu" or, more euphemistically, "redolent fermented tofu."

In Japan fermented tofu is largely unknown except in Okinawa and by a few microbiologists. The latter generally call it nyufu ("milk spoiled"), or funyu . In Okinawa there is a unique, mellow type of fermented tofu with a unique name, tofu-yo , which first appeared in 1832 in the book Gozen Honzo by Tokashiki. The origin of this term is unclear, but it is probably a local pronunciation of the Cantonese tofu-yu . However Okinawan Japanese write the character for yo using various rare characters not generaly used for fermented tofu in China, and not even widely known in Japan. The character for yo most widely used to day was first used in 1938 by SHOJUN Danshaku; in other contexts it is usually pronounced ko and means "flour mochi" ( konamochi ). Nowadays writers often use hiragana to write the yo in tofu-yo (Yasuda 1983).

As Chinese fermented tofu spread to other countries in East and Southeast Asia, it was given new names. It is known in the Philippines as tahuri or tahuli , in Indonesia as taokoan or takoa , in Malaysia as tau ju , in Thailand as tao-koan or tau-hu yee , and in Vietnam as chao or dau-phu nhu .

In about 1906 Quong Hop & Co. in San Francisco began to label the fermented tofu they manufactured as "Fuyu (Bean Cake)". This was its earliest known English-language name. In 1916 Frank N. Meyer (Nov. 21) called it "Chinese soybean cheese" and "Chinese bean cheese," but in most subsequent communications during 1917 he called it simply "bean cheese." Dr. Yamei Kin ( New York Times Magazine 1917) referred to it as "the cheese, a cross between Camembert and Roquefort, and made from the soy bean . . ." Shih (1918), writing from China in English, called it Ju Fu . Palen (1919) referred to an imported Chinese product as "red bean cheese." In 1920 Margaret Church of the USDA first referred to it as "Chinese cheese." In Wai's famous study of 1929, he called it "Chinese soybean cheese" in the title but sufu (or tosufu ) in the text. Morse (in Dorsett and Morse 1928-31) used terms such as "pickled soybean curd," "pickled curd," "bean curd pickled." From the 1930s, the names "sufu" (due to Wai's influence), "soybean cheese," and "Chinese cheese" (in approximately that order of popularity) were used by most writers. Unfortunately most of the Western writers who used the term "sufu" failed to understand that it was not the standard Chinese term, but rather one derived from a relatively unknown dialect. In 1975 in The Book of Tofu , Shurtleff and Aoyagi first called the product by its standard Chinese Mandarin name, but wrote it phonetically as doufu-ru to avoid mispronunciation. In 1979, in a revised and Americanized edition of their book, they coined and used the term to "fermented tofu." Americanized names for the many types of fermented tofu were also given. Anderson (1977) called this product "pickled bean curd." Bernstein (1982)

called it "preserved bean curd."

In French ??

Western Mold-Ripened Dairy Cheeses . It is interesting to note that mold-ripened dairy cheeses, quite similar to some of the types of fermented tofu mentioned above, have long been well known in the West. Here the most popular varieties are Roquefort, Blue (also called Bleu or Blue-veined), Camembert, Brie, Neufchatel, Gorgonzola, Stilton, Gamelost, and various others. These are produced in Europe and North and South America. Mold-ripened dairy cheeses have a long history. The first was shipped to Rome from southern France as early as A.D. 250 and the name "Roquefort" first appeared in 1070. Most of these cheeses are ripened with molds of the genus Penicillium , such as Penicillium roqueforti and P. camembertii . Some (Brie, Camembert, etc.), like fermented tofu, are surface ripened: the mold grows on the surface. In the blue-veined cheeses such as blue/bleu, Roquefort, Gorgonzola, and Stilton, the mold grows inside the cheese; aeration is provided by a dry, somewhat crumbly curd structure and, often, perforation with needles. The most popular mold-ripened cheese in the US is Blue, which accounts for about 1% of total US cheese production (Nelson and Richardson 1967).

History of Fermented Tofu in China . Fermented tofu is generally thought to have originated in China, but the time and place of origin are very uncertain. According to Ohta (1965) and Yasuda (1983, H-2 and R-26) a Japanese researcher named Yamazaki found a reference to a type of fermented tofu called called rufu in the Gokuhen (pr??), a document published about 1,400 years ago during the Six Dynasties [A.D. 222-589]. Nakano (1967), apparently drawing on the same source, wrote: "Records show that about 1500 years ago, at the end of the Gi?? (Jap) period, tofu was dried, salt was added, and it was immersed in moromi [probably jiang or unpressed soy sauce, see Chapter 40] until it ripened to form fermented tofu [ nyufu ]." Ohta (in Watanabe, Ebine, and Ohta 1971) repeated Nakano's statement almost word for the word but added that the documents which showed this were ancient ones

Unfortunately and surprisingly neither Ohta, Yasuda, nor Nakano gave any reference to the original Chinese document mentioning fermented tofu, NOR to Yamazaki's publication!!??. (Does Ohta 1965 cite Yamazaki?? Shih 1937 cites 2 articles by Yamazaki!! 1920-25; 1931) If their statements about the 5th century origins of fermented tofu are true, which we feel is unlikely, it would be of great historical significance, since the earliest known reference to tofu itself in China dates from only the 10th century, in the Ch'ing I Lu of 950.

The earliest known verifiable reference to fermented tofu appears in the famous Chinese materia medica, Pen-ts'ao kang-mu by Li Shih-chen (1578-97). There it was stated that " rufu ["milk + spoiled"] is also called rupei ?? ("milk + mochi")". It is not clear why the character for mochi (pounded glutinous rice) should be associated with fermented tofu, except that they are both smooth in texture and cream colored.

According to Wai (1964, 1968), fermented tofu was mentioned in the Food Encyclopedia (Chinese name??) written by Wang Su-Hsiung (1861 Ref??) of the Ch'ing dynasty. It reportedly stated that "Firm tofu is not easy to digest, and it is not good for children, old people, or invalids. Fermented tofu, which is prepared from tofu and gets better the longer it is aged, is very good for sick people." Wai concludes that fermented tofu was probably being made in China long before the Ch'ing dynasty (1662-1912). Although there are no records, it was probably during the Ch'ing dynasty that fermented tofu began to spread from China to other countries in East and Southeast Asia.

From the time of its development until the present, most of the fermented tofu in East Asia was probably made in people's homes or in small shops. The firm tofu was inoculated by placing cubes of it on a large bamboo tray and covering them with ordinary rice straw, on which the mold grows naturally, and allowing them to stand at room temperature for 3-4 days until a dense mycelium formed. The brine fermentation was then carried out in an earthenware crock.

The first mention of fermented tofu in an English language document appeared in 1918 in Shih Chi Yien's Beans and Bean Products , an excellent monograph published by the Biology Department of Soochow University, in Kiangsu Province, west of Shanghai. The author described three types (including eight varieties) of fermented tofu and gave detailed (although not completely clear) instructions for their preparation: 1. Ju fu (including (a) Jiang ju fu made with unmolded firm tofu, a white mold powder grown on wheat flour cakes, salt, rice wine soy sauce, sugar solution, and "red rice" aged for 4 months; (b) a similar product made with molded tofu; and (c) the same product with diced ham mixed in. 2. Tsao ju fu , similar to 1b, but with the molded tofu cakes being thoroughly salted and put in an earthenware crock for 4 days, then covered with sake lees ( chiu niang ) and aged for 2 months. 3. Ch'ing hsien ju fu , made from molded tofu cakes, which were salted then aged in a brine solution for 10-12 days.

The first scientific studies on fermented tofu were published in 1928 and 1929 by Mr. Nganshou S. Wai, chief chemist of the National Hygienic Laboratory, Shanghai, and a native of Chekiang province, where fermented tofu was known as sufu . (Recall that Shih had also been from Shanghai.) Wai had graduated in biochemistry from the Japanese Imperial University, Kyoto, and then worked for two years with Prof. Genitsu Kita, whose studies on fermentation and shoyu were well known. Wai's first report was published in Chinese in December 1928 in the Agricultural Journal of the Agricultural College, National Central University, Nanking (Ref??). A summary was published in Science magazine in English in 1929 as "A New Species of Mono-Mucor, Mucor sufu, on Chinese Soybean Cheese" (Coville 1929). Prior to Wai's studies, the tofu fermentation had been considered a "spontaneous natural phenomenon." Wai isolated the main microorganism thought to be responsible for the fermentation and identified it as an undescribed species of Mucor ; he proposed the name Mucor sufu . He thought that this mold originally lived on rice straw, which was always used to cover the tofu cubes in the traditional fermentation process. He also stated that sufu (or tosufu ) was made in large quantities in the region of Shoushing (Chekiang Province) and in Soochow, Wushih, and Changkow (Kiangsu Province). Some 35 years later, starting in 1964, Wai continued his publications on fermented tofu. At that time, however, he was working in Taiwan (see below).

Wai's research during the late 1920s prompted more. Wei (1930) isolated some species of Mono-Mucor molds from samples of fermented tofu obtained at Shaoshing (Chekiang province) and Suchow (Kiangsu province). Liu (1932a,b) studied the microorganisms on varieties of both red and white fermented tofu obtained in Hangkow; he found at least seven genera and published a detailed study of the enzymes produced by the molds (Shih 1937).

A. K. Smith (1949) of the USDA, following his visit to China in 1948, described three varieties of fermented tofu, which he called "soybean cheese;" these were called chee-fan , tsue-fan , and hon-fan , each apparently made in Hangchow, just south of Shanghai. The names were from the local dialect. It was now becoming clear that fermented tofu had traditionally been made primarily in the provinces along the southeast coast of China, from Shanghai in southern Jiangsu province, down through Zhejiang, Fujian, and Guangdong provinces, as well as in Taiwan (located off the coast of Fujian province).

Following the establishment of the People's Republic of China in 1949, the many traditional varieties of fermented tofu continued to be widely consumed. The more popular of these varieties were sold at Jiang Gardens, typically in 500-ml glass jars. Harris (1949) gave a nutritional analysis of redolent fermented tofu ( ch'ou tou fu lu ) and noted that "it is used as an appetizer by the wealthy and as a main dish by the poor in many provinces." In southern China (Hunan or Hupei) it is apparently fried to make the famous cha ch'ou doufu , which is served with hot sauce. Redolent fermented tofu is said to have been Chairman Mao's favorite dish; it is widely sampled by visitors to his home province of Hunan. The former "Stinky Doufu" has been renamed "Hibiscus Doufu." (By whom? why?)

The most popular way of serving fermented tofu in China continued to be as a seasoning for hot breakfast rice or rice porridge ( shi fan , also called congee). Some people prefer to use the tips of their chopsticks to take a tiny piece of fermented tofu (placed by itself on a small dish) with each bite, whereas others like to mix the fermented tofu (and often some of its brining liquor) in with the porridge before starting the meal. Fermented tofu is also used to make a dipping sauce for live "dancing shrimp" or (in Sichuan) various other foods, including lamb. It is also widely used in cooking (especially stir-frying) to season vegetable, fish, or meat dishes (Shurtleff and Aoyagi 1975; 1983; Lin 1977).

Relatively little on fermented tofu has been published in English by Chinese scientists since 1949. Guo (1983) reported that calcium sulfate and calcium chloride were inappropriate for use as coagulants to make the tofu for fermented tofu. Rather the whey from regular tofu, which was allowed to stand for 2 days until it soured to a pH of 4, was used as the coagulant. The curd was then wrapped, pressed, cut, fermented, salted, and packed in an earthenware vessel for 6 months.

History of Fermented Tofu in Taiwan . Nothing is known of the early history of fermented tofu in Taiwan, except that it was probably fairly widely produced there since early times, as it was in each of the southeastern martitime provinces of China.

In 1964, N.S. Wai, who had done the earliest known scientific research on fermented tofu in China during the late 1920s and was now living in Taiwan, published a detailed study of fermented tofu entitled "Soybean Cheese" in the Bulletin of the Institute of Chemistry , Taiwan. And in 1968 he published the final synopsis of his studies in a report of research funded by the United States Agency for International Development. Here he stated that the primary mold used in factories was Actinomucor elegans (actually Wai termed it Rhizopus chinensis var. chungyuen ) and that the same strain was used by all three of the fermented tofu manufacturers he visited in Taipei, as well as by six manufacturers studied in Hong Kong and Kowloon. Fermented tofu made at home in Taiwan, however, utilized Mucor hiemalis and M. silvaticus . Wai developed a pure culture fermentation and described the various types of fermented tofu with nutritional analyses: red sufu, tsao sufu, Kwantung sufu, Yunnan sufu, and rose sufu.

Simonds (1979) wrote colorfully in Gourmet magazine of fermented tofu in Taiwan: "Stinky bean curd ( ch'ou tou fu ) is a favorite snack of the Chinese. Vendors of this unsavory--at least to my unsophisticated palate--delicacy run rampant all over the city of Taipei with their portable deep fryers. The children in my Chinese family's house, all great fans of the stuff, used to race outside excitedly with empty plates at the stinky bean curd man's call. (The smell usually preceded him by two blocks). This fermented bean curd is generally deep-fried and eaten with a choice of soy sauce, vinegar, mashed garlic, and chili paste."

In 1977 L.P. Lin and Y.C. Su, both from the Department of Agricultural Chemistry, National Taiwan University, Taipei, presented in-depth studies of fermented tofu (sufu) and its methods of preparation; these were published by Stainkraus (1983). Su estimated that production of fermented tofu in 1977 was approximately 10,000 tons, and per capita consumption was about 12 gm a week.

Fermented tofu, is increasingly imported from Taiwan to the US, where it is winning converts. Anderson (1982, pers. comm.) has lauded one such import labeled "Bean Curd Preserve with Rice Sauce" ( mi-jiang furu ). Ingredients were "bean curd, soybeans, rice (probably koji), salt, sugar, and wine [probably Shaoshing or a close relative]. The product and its thick sauce were milder than most, and the split soybeans were unique.

History of Fermented Tofu in Japan and Okinawa . Although fermented tofu has never been widely known or consumed in Japan, it has a long and interesting history there, especially in Okinawa (a major group of islands in the Ryukyu Islands), where a mellow, delicious product named tofu-yo has been enjoyed for at least 150 years. Recent publications by Dr. Masaaki Yasuda, Associate Professor of Agricultural Chemistry at the University of the Ryukyus in Okinawa, have thrown new light on this food and its history (Yasuda 1983). The following history draws largely on Dr. Yasuda's research.

The Ryukyu Islands, stretching some 500 miles from the southern tip of Kyushu (Japan's southernmost main island) past the coast of China down to Taiwan, have long had strong cultural ties with both China and Japan. During Japan's Edo Period (1600 to 1868) the kingdom of Ryukyu formally belonged to China, but in fact it was more closely tied with the Satsuma Han, a powerful domain in southern Kyushu. Like China and Japan, Ryukyu had its own emperors and dynasties. The imperial palace was in Okinawa, in the southern city of Shuri. Imperial messengers ( sakuho-shi ) were frequently sent to Okinawa from China and there were cultural exchanges between the two countries.

The earliest known reference to soybeans in Okinawa appeared in 1534 in the Record of the Messengers to Ryukyu (R-16). Thereafter soybeans became a widely grown crop (R-17).

The History of Ryukyu by Ryukyu Opu (1713, R-19) noted that it was not clear at the time when and how tofu came to the country. Although this uncertainty still remains, tofu is thought to have arrived in Ryukyu by the mid-1600s. According to the Records of the Messengers to Ryukyu written by O-sho? (Wang-shu?) in 1683 (R-18), tofu was widely available at that time in Okinawan market places, being produced by many companies. It was an important food not only for the local people, but also for the Chinese imperial messengers (R-20, R-21, R-22). Okinawa's tofu was a firm tofu, made in the Chinese way by pressing out the soymilk before cooking. This method was also traditionally used in Korea and southern Japan (in Kumamoto, Yamaguchi, Ishikawa, and Koichi prefectures). The method was probably introduced to Okinawa by Chinese imperial messengers or by exchange students, although it could have been brought from Japan by Buddhist monks, who served it in their temple cuisine.

Interestingly, the earliest known reference to fermented tofu in Japan comes from Osaka (Sakai?, an international port having considerable trade with China) rather than from Okinawa. In 1783 Ka Hitsujun of Osaka? wrote his famous book Tofu Hyakuchin Zokuhen (100 More? Favorite Tofu Recipes). In the section on "Unusual Foods" ( Kihin ) he wrote: "Red tofu ( beni tofu ): The method of making it is a family secret, not revealed to others. Fermented Tofu ( tofuji ): Put koji in white sake ( shirozake ; what is it?), grind it well in a mortar, then mix in red koji (or other? hot-spicy things) and hot peppers? (How say in Japanese; see Dict?)". This product was apparently a type of Chinese fermented tofu.

In Okinawa, neither red tofu nor fermented tofu ( furu or doufuru ) are mentioned in the Ryukyu's old language dictionary ( Konpo Kenshu ??) of 1711, nor in the History of Ryukyu ( Ryukyukoku Uraiki ??) of 1713.

Fermented tofu was probably introduced to Ryukyu and Okinawa during the late 1700s or early 1800s. The earliest known indirect reference there was by an Englishman, Basil Hall, who visited Naha harbor in 1816, on his way from China. He and his party were entertained by the Ryukyu government and served the local cuisine. In his book Account of a Voyage of Discovery to the West Coast of Corea and the Great Loo-Choo Island (1818), Hall reported being served "hard boiled eggs, cut into slices, the outside of the white being colored red. . . Sackee [ sake ]. . . and something like cheese (p. 96-97*). The red color was probably imparted to the egg by red koji ( beni koji ) and the food resembling cheese may well have been fermented tofu (which is often also made with red koji) (R-30).

The earliest known direct reference to tofu-yo (Okinawan fermented tofu) and red koji appeared in 1832 in the Gozen Honzo , a book about food and medicine written by the physician TOKASHIKI Tsukan Peichin (R-9). Peichin is a term for a high-ranking officer. He wrote that "Tofu-yo has a delicious flavor and is good for the stomach. It makes eating a pleasure and is good for various types of sickness."

Yasuda (1983) has speculated that Chinese fermented tofu ( doufuru ) was brought to Ryukyu during the early 1800s (perhaps during the Ryukyu Ocho?? or Sho Ko dynasty, 1804-1828) in the cultural exchanges between the two countries. It was consumed largely by the upper classes, both as a medicinal food and as a side dish. They learned how to make it but kept this method secret. This may explain why its use did not spread and why so little was written about it. However the Ryukyu royal family and nobility probably found the rather strong aroma and flavor, the saltiness and the spiciness of the Chinese product to be somewhat unsuited to their tastes. So they began to change it, creating a product with a simpler, mellower flavor, made with a famous local millet brandy (a relative of sake) called awamori .

According to Yasuda (1983) there were no known written references to tofu-yo from 1832 until the 1930s??. It is not mentioned in the subsequent records of Chinese imperial messengers, in the accounts of visits to Ryukyu by the Americans Beechey (1831) or Commander Perry (1857), nor in any documents from the Meiji period (1860-1926).

During this period, while China was militarily weak, the increasingly powerful Meiji government in 1871 made Ryukyu a part of Kagoshima prefecture, then in 1872 renamed it Ryukyu Han (feudal domain), but allowed the existing emperor, Sho Tai, to continue his rein. Finally in 1879 Japan formally conquered Ryukyu, renaming it Okinawa prefecture.

During the Taisho period (1912-1926) and the early Showa period (1926 to present), according to a survey of old citizens of Okinawa done by Yasuda (1983), tofu-yo was popular among the upper classes in the Okinawan cities of Shuri (the former capitol) and Naha (the new capital and a major port?). It was eaten with tea by the ladies or with awamori (an Okinawan sake made from millet) by the men. Typically a small cube (roughly 3/4 inch on a side) was placed on a small dish and eaten, a little at a time, with chopsticks or a tooth pick. The regular people couldn't afford tofu-yo, since it was very expensive.

In Naha there was a large area called Tsuji-machi (Tsuji-town), and within it was a thriving, licensed and segregated "red-light" district ( yukaku ), with over 300 "houses" run by women, who served as entertainers and prostitutes. Many of these women (called anman ) had been sold to the owners of the houses by very poor families. The women, renowned as excellent cooks, learned to make tofu-yo themselves. They were said to make it with all the same tender loving care that other women might devote to their children. Like the kings and nobility before them, they too kept their methods for making tofu-yo a secret. One secret was said to be the 3-4 month fermentation in very strong awamori (sake). They served it to their male guests (clients) as a high-class hors d'oeuvre, and soon the tofu-yo from Tsuji became quite popular, developing the reputation as being the finest available anywhere. Its mellow flavor and soft "melt-on-the-tongue" quality came to be especially prized. In 1926 there were about 300 houses of "entertainment" in Tsuji and many featured tofu-yo, which came to be called "the taste of tsuji." It was from Tsuji that the reputation and use of tofu-yo began to spread throughout Okinawa (NHK 1985).

Scientific research in Japan on fermented tofu and its microbiology began in the early 1900s. The famous microbiologist Keizo?? Takahashi is thought to have written a scientific report in about 1900 (Ohta 1983, pers. commun.), but we have been unable to locate the document?? (See R. Nakazawa Hakko Bunshu under Nyufu; Furu; Toufuru; Mucor; Rhizopus??) The Japanese microbiologist M. Yamazaki (1920-25; 1931; from where??) published research on the use of molds and other fungi in food fermentations in China, and on their history (Shih 1937). Was he the one who found the reference from 1500 years ago?? Cite the source?? The earliest?? known scientific article by a Japanese on fermented tofu was in 1932 by Liu, a Chinese doing research at Hokkaido Imperial University's Department of Agricultural Chemistry. He called the food nyufu , discussed the chemical changes taking place during its fermentation, and showed that ripening was caused by enzymes from the mold.

In June 1938 a man named SHOJUN Danshaku, a descendant of the Ryukyu royal family and a well-known connoisseur, wrote an interesting 7-page article titled "In Praise of Tofu" in the magazine Monthly Ryukyu . He noted that in mainland Japan, there was no cookery using fermented tofu. But in China and Okinawa fermented tofu had been made for a long time. Chinese gourmets call it dou-ru and prize even more highly than swallows nest and trepang. He found the flavor of Chinese red fermented tofu overpoweringly strong, but was impressed with way Okinawans had used awamori to make tofu-yo less salty and less strong in flavor. Popular Okinawan dishes featuring tofu-yo were Itami Rokuju ("Sauteed Sixty" served with rice porridge), Sen Rokuju-age ("One Thousand Sixty Deep-fried"), and Itami Tofu (Fried Tofu). In each case well-ripened tofu-yo was fried. The best time for making tofu-yo was from June to September. Finally Shojun philosophized:

If you search throughout this world for foods which can match the good taste of tofu-yo, you will find the cheeses of France, the caviar of Russia, as well as natto and salt-pickled sea urchins (uni no shiokara) from Japan. But old cheese is not liked by everyone, while sea urchins and caviar lack the robust, rich flavor of tofu-yo and are thus less satisfying. Therefore I think that tofu-yo is one of the best rare and tasty foods (chinmi) in this world--if not the best.

In 1969 this article was reprinted in a book titled Matsuyama Oji Shojun Iko (the posthumous collected writings of prince Shojun of Matsuyama in Ryukyu), edited by Yamazato Eikichi. It introduced many mainland Japanese to tofu-yo.

Starting in the 1960s Japanese microbiologists began to take a growing interest in fermented tofu, which they called nyufu (the characters mean "milk spoiled"). Reports were published by Ohta (1965, Hakko Kyokai Zasshi , 60(7):8-??), Nakano (1967), and Matsuoka et al. (1968). Nakano classified fermented tofu into two types (based on whether or not mold was grown on the tofu initially) and ten varieties. He described the characteristics of each variety in a detailed table. The source of his information, "a survey done in Shanghai in about the 1920s," may have been Shih (1918). Ohta (1971, in Watanabe, Ebine, and Ohta), Okada et al. (1974), Nakano (1979), and Watanabe (1984). This interest grew in part from the chance to investigate a "new" Asian fermented soyfood, but perhaps even more from the potential to develop truly new cheeselike foods by fermentation of tofu. Japanese scientists pioneered in this latter area during the 1960s and 1970s, as described in the next section.

During the early 1980s, interest in tofu-yo grew steadily in Japan. Kurima (1982) discussed it briefly in an article on Okinawan foods, noting that the flavor was best after 6 months of aging and that tofu-yo was now found mostly in restaurants specializing in traditional Okinawan cuisine, such as Urizun in Naha city.

But the man most responsible for introducing tofu-yo to Japan and the world is Dr. Masaaki Yasuda from the University of the Ryukyus. During 1983 and 1984 he and his colleagues wrote a series of six scientific articles about tofu-yo and red koji ( beni koji , which is always used in making tofu-yo). These included a detailed and carefully documented history (with 37 references) and a precise description of the process by which tofu-yo is made. Yasuda presented a poster session on tofu-yo in English at the 1985 Tsukuba symposium on unsalted (or low-salt) fermented soyfoods in Japan.

Then on 9 March 1985 NHK TV, Japan's largest and most respected television station, did a 30-minute documentary titled "Tofu-yo," as part of its series "Today's Food." Filmed in Okinawa, it showed step by step how this delicacy had been made in one family's home for three generations: Dry a large cake (5 x 9 x 12 in.) of lightly salted, firm tofu outdoors on a flat bamboo tray, turning it many times daily, for 4 days, until it becomes yellow. Cut it into 1-inch squares (3/4 inch thick), then wash these with 2-3 times with awamori (millet brandy). Soak white koji and red koji separately in awamori for 2-3 days until soft, then grind them separately in a serrated earthenware mortar (suribachi); finally grind them together. Stir in a little salt, then the tofu. Pack the mixture into a large glass jar (2-4 liters; wooden crocks used to be used) and leave it to ferment for 3-6 months. Remove the pinkish pieces of tofu-yo and serve to men with awamori. The remaining thick beige koji grog (called nuta ) is typically eaten by the women with their hot cooked rice.

The film also showed the one shop out of 300 in Naha's central Kosetsu market that sold reddish tofu-yo (in a plastic bag inside a box) and one of Okinawa's 2-3 restaurants that served it (with awamori). There were only a few people in Okinawa who still knew the difficult and time-consuming process for making tofu-yo, which was clearly not widely consumed, although its popularity was now apparently growing. The film also discussed tofu-yo's history in Tsuji, and showed a photograph of Shojun Danjaku and his hand-written text. A summary of the documentary was published in the March issue of Kyo no Ryori.

As of 1985 only one small plant (K.K. Maruyama in Naha city) was producing tofu-yo commercially in Okinawa. The plant's owner, Mr. Yamada, also sold his product in Tokyo's fanciest department stores (Matsuzakaya in Ginza and Seibu in Yurakucho); 8 pieces in a glass jar retailed for 2,000 yen. He also planned to export it to the USA and Europe, packed it in small pottery crocks. At least one restaurant, Urizun, which opened in 1972 and featured awamori, also sold its tofu-yo in a handsomely packed wooden box, over the counter.

In mainland Japan, Chinese-style fermented tofu is even less well known. It has never been made there and is sold only at a few Chinese food stores. Few Japanese have even heard of it and those who taste it generally find the flavor and aroma much too strong.

In the mid-1980s tofu-yo began to be known outside of Japan. In a article on Okinawan cuisine in the New York Times (10 June 1984), Stinechum mentioned that it was served at Urizun with awamori. In May 1985 Soya Foods , the ASA newsletter published in Belgium, summarized an article by Yasuda and Hokoma about tofu-yo. In September Yasuko Torii, a Japanese whose mathor was Okinawan, brought some tofu-yo and information about it to Shurtleff and Aoyagi at the Soyfoods Center. They liked it very muchas did a number of visitors to whom they served it. That month Shurtleff began a correspondence with Dr. Yasuda in Okinawa.

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