History of Natto and Its Relatives - Page 2

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A Chapter from the Unpublished Manuscript, History of Soybeans and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 Soyinfo Center, Lafayette, California

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Taisho Period (1912-1925). As new train lines expanded in Japan, Iwadeyama natto in Miyagi prefecture north of Tokyo started to be mass produced and distributed outside the prefecture. Yet as large-scale production increased, so did problems of temperature and oxygen control, contamination, and product failure. Since the findings of Japanese microbiologists had not yet begun to affect actual commercial natto production, producers had no idea what was causing their problems. Soon several major producers (including Mr. Sasanuma, the first producer of straw-wrapped natto packets) declared bankruptcy. Increasingly producers turned in despair to Buddhist monks and Shinto priests, asking them to chant sutras, pray, or ritually purify the incubation rooms. Producers carefully guarded their production secrets and superstitions from one another and tried to steal the secrets of successful producers, but they still failed to make good natto.

In 1912 Dr. Shinsuke Muramatsu of the Morioka College of Agriculture, Iwate prefecture, published "On the Preparation of Natto" in English. He noted that natto was consumed mostly in the northeast prefectures in the winter (Aizu in Fukushima prefecture was especially noted for its natto production), and in Tokyo in the summer. He studied the role of rice straw in the fermentation, noting that fresh rice straw gave the best product, and that the use of rice straw was important in producing a top quality product since it imparted to the natto a desired flavor, and aided ventilation and absorption of free ammonia. After discussing the findings of Yabe, Sawamura, Monzen, and Muto?? concerning the natto bacteria, he gave a detailed analysis of the three principal bacilli he isolated from various natto samples. He found that all three Bacillus species or strains produced fine natto with strong viscosity and good aroma at 45*C, but that Bacillus No. 1 produced the best product. Thus Muramatsu recommended its use in the form of a pure culture. He concluded by giving the first nutritional analysis of fresh and several-day-old natto and noting that the natto bacteria "secrete trypsin and diastase (enzymes), so that when we take natto together with several foods rich in protein or starch, they may be digested more rapidly than when they are taken alone." Soon Dr. Muramatsu started producing his "College Natto" at the agricultural college; his students helped to make and sell it, as a source of income, and it became very popular.

Another important event of 1912 was the founding of the Natto Manufacturers Association of Tokyo by six local producers. In 1954 it was merged into the newly formed Japanese National Natto Association ( Zenkoku Natto Kyodo Kumiai Rengokai ).

In 1919 Dr. Jun Hanzawa, of Hokkaido University's Department of Agriculture, made two key breakthroughs that helped to bring natto production out of the "Dark Ages." In 1919 and 1938 (Refs??) he published the results of his investigations, which included important work on the taxonomy of natto bacteria. Serving simultaneously as a microbiologist, an extension worker, and a pilot plant operator, Dr. Hanzawa began by producing a pure culture bacterial inoculum for natto; this allowed commercial natto makers to discontinue, for the first time, the use of straw as a source of inoculum. Secondly, disliking the use of straw even as a wrapper, he developed a simple, low-cost method for packing, incubating, and selling natto wrapped in paper-thin sheets of pine wood ( kyogi ) or small boxes of pine veneer ( oribako ). A third important improvement followed shortly: the development of a new incubation room design ( bunka muro ), which had an air vent on the ceiling and substantially decreased the natto failure rate. These three developments laid the basis for modern industrial, sanitary, scientific natto production. Dr. Muramatsu began distribution of his pure culture starter and laboratory-scale production of his hygienic natto. Commercial natto producers filled his classes and he worked as a consultant for them. Like Dr. Muramatsu before him, Dr. Hanzawa sold his "University Natto" from his research lab, promoting it as a rival to cheese, full of nutrition and an aid to digestion. In the process he raised money to support his lab, aided the spread of applied microbiology, and popularized modern natto production. Eventually his low-cost product became so popular that traditional rice-straw natto producers got upset and started doing counter propaganda. Soon, however, natto was being produced commercially in local Sapporo city using his method; it quickly spread to the rest of Japan, and eventually to Manchuria, China, and South America among the Japanese living in those foreign lands. In 1971 Dr. Hanzawa, who had long before earned the appellation of "the father of modern natto production," was given the honor of addressing the emperor of Japan on the subject of natto.

Showa Period (1926-1981 and beyond). In the modern period, serious medical and nutritional studies on natto were started. Traditional folk wisdom had it that natto helped in curing many types of diseases (perhaps because its bacteria suppressed harmful bacteria) and aided digestion (via its proteolytic enzymes). In Akita prefecture, for example, natto was thought to help prevent tuberculosis and in Ibaragi it was considered a remedy for colds and flu. In 1929 Dr. Yu Eguchi (Ref??), a navy physician, did a series of experiments indicating that natto bacteria could be used to prevent typhus and dysentery in laboratory animals. In 1932 Dr. Nakano (Ref??), a navy lieutenant commander, used natto bacteria to cure people who had dysentery. In 1936 Dr. Matsumura (Ref??), a Kyoto University bacteriologist, discovered that natto bacteria killed typhus bacteria in rabbits. He first fed the rabbits typhus bacteria, then natto; a subsequent examination of the rabbits showed that the typhus had disappeared. The story made headlines in Japan.

By 1935 in Yokote, Akita prefecture, split-bean ( hikiwari ) natto had become very popular; 70 out of 73 families produced it at home and sold it in nearby villages. In 1936 Mito Natto started to be sold on the platform of Mito station and soon became very popular.

Throughout its long history in Japan, natto had developed a close association with the military and had come to be highly regarded as a wartime food. The same pattern emerged prior to and during World War II. Japanese ships and submarines regularly took soybeans and natto culture on board; natto was highly regarded as a tasty and inexpensive source of energy, protein, vitamins, and minerals, plus an aid to digestion and disease prevention. It was said that some ships got so hot inside during the summer (42*C or 108*F) that natto could be made without a special incubation chamber. Japanese pilots who had to climb quickly to high altitudes in fighter planes as they tried to intercept B-29 bombers were found to develop severe problems from expansion of intestinal gasses. Dr. Shoji Iwadare solved this problem by having the pilots eat natto before their flights. He later wrote extensively about natto in two books: The Japanese Way to Long Life (1968) and Miso, Natto, Tofu: The Way to Health (1976, which drew heavily on Ohta 1975). Dr. Eguchi, whose work on natto, typhus, and dysentery had made him Japan's most famous natto researcher, wrote a report in 1942 (Ref??) in which he urged the Japanese to popularize natto as a tasty, nutritious food that could build good health and prevent disease. He encouraged its spread to the people of Southeast Asia. Before World War II, consumption of natto was confined almost exclusively to that part of Japan north of Tokyo and especially to the northeast prefectures. The widespread use of natto by the army and navy, however, and the fact that it was included in the Japanese food rationing program during and after the war, introduced natto to many people from other parts of Japan who had never tasted it before. After the war it came to be enjoyed increasingly nationwide. Figure ??.? shows 1968 data for average per capita yearly expenditures on natto in a number of major Japanese cities, illustrating the nationwide spread. At this time natto retailed for 4-6 cents (US) per 100-gram packet or 18-27 cents a pound.

After World War II two of the Americans in charge of food and nutrition at the General Headquarters of the American occupying forces, Colonel Hobb and Ms. Appleton, regarded soybeans and natto highly and encouraged their use, importing lots of soybeans from America. Nagasawa Takeshi (Ref??) of the Japanese Department of Agriculture called natto "Soybean Cheese" and stimulated its use by pointing out that in 1946, compared for example with chicken, it provided 3.0 times as much protein and 2.7 times as much energy (calories) for the same price. In 1949 Yamazaki Momoji and Miura Jira (Ref??) wrote "Rational Natto Production" to aid modernization of the industry.

In 1953 Sakai published an extremely important article (in Japanese) on "Production of Vitamin B-12 by Microorganisms." It contained the first known reference to the existence of vitamin B-12 in a soyfood, in this case natto, which was found to contain 0.1 to 0.3 micrograms of B-12 per 100 grams. Sano (1961) also found an increase in B-12 during natto fermentation.

In 1959 Japanese Ministry of Agriculture Food Research Center and the Japanese National Nutrition Research Center, under request and funding from the United Nations' UNICEF, began cooperative research to develop a dried powder from natto, for use as a protein supplement for children in biscuits, crackers, soups, and the like. There was also interest in mixing the natto powder with chlorella, then a newly developed microalga. Natto was prepared as usual except that the fermentation was reduced to 6-8 hours from the usual 18-24 hours. The natto was then press ground into noodle shapes or spread on trays, dried under vacuum to 4% or less moisture, and ground to pass through a 40-mesh screen. The resultant product had a light yellow color, light fragrance, and delicate flavor, with no beaniness. Animal feeding experiments showed a high absorption rate (83%) and biological value (63), higher than those of cooked soybeans. While the 3-year project was not able to generate enough information to lead to commercial production or practical applications, it did lead to a wave of research articles on natto fermentation and nutrition, published in Japanese with English summaries. Hayashi (1959a, 1960), in the most comprehensive studies to date on nutritional changes during natto fermentation, found that riboflavin (B-2) increased roughly three-fold to five-fold, while carbohydrates virtually disappeared. Amino acid composition was unchanged. Sakurai (1960) reconfirmed that B. natto is an aerobic, gram-positive, rod, related to B. subtilis. Sakurai and Nakano (1961) gave a general report on the UNICEF project, noting that the new powder improved natto's keeping properties and broadened its use. Arimoto (1961) found that the addition of 15% powdered natto to biscuits, 20% to crackers, and 5% to curry was well accepted by school children. Rats fed on a diet containing natto and rice grew as well as those on an ideal lab diet. Natto had a Protein Efficiency Ratio (PER) of 2.6, a biological value of 55, and a digestibility of 72 (based on work also done by Standal in 1963). Kihara et al. (1961) reported on the chemical/nutritional constituents of natto. Muto et al. (1963) did the first known nutritional studies of natto on humans, testing it as a protein source in infant diets. They concluded that it could be substituted, at least in part, for animal protein, to maintain adequate growth, digestibility, and nitrogen retention. Some researchers (Matsuno and Tamura 1964 Ref??) found feeding experiments with rats to show that the nutritive value of natto was somewhat less than that of unfermented cooked soybeans, but others cited above, found the opposite.

In 1958 Dr. A.K. Smith of the USDA visited Japan to study soyfoods. He described the basic natto production method at that time: 1/3 cup cooked soybeans was inoculated with a pure culture, wrapped in a paper-thin sheet of pine wood, and incubated at 40-43*C for 18-20 hours. He noted that there were 800 natto producers throughout Japan, including 80 in Tokyo alone.

In 1961 the Japanese National Natto Festival was inaugurated; sales increased rapidly, especially in parts of Japan where natto was not traditionally eaten.

In 1969 Dr. Teruo Ohta of the Japanese National Food Research Institute published a comprehensive article on natto in Shokuryo (Foods) magazine, establishing him as one of the top researchers in the field. In 1971 he wrote an even more detailed and comprehensive chapter on natto in the excellent book Soyfoods ( Daizu Shokuhin ; coauthored by Watanabe, Ebine, and Ohta), and in 1975 he wrote an entire book on natto, The Natto Way of Health ( Natto Kenkoho ). Our chapter has drawn heavily on his writings.

In 1975 the Japanese National Association published the voluminous Natto History and Development (Natto Enkaku-shi), edited by K. Yokotsuka. In 1977 the first issue of the Natto Kagaku Kenkyu Kaishi (Natto Scientific Research Journal) was published by Natto Scientific Research Society. It contains excellent, detailed research studies, some in English or with English summaries. During the 1970s a number of advances in natto production were made. Small-seeded soybeans (especially those from China) were preferred. They were pressure steamed at 15-22 psi for 20-30 minutes, inoculated with a pure culture of Bacillus natto when they were still at 80*C or above, transferred to small polystyrene or polyethylene trays (each with a cover) in 1/3 cup or 100-gram quantities, and incubated at 40-50*C and 70% humidity for 14-18 hours in a modern incubation room, then cooled to 2-7*C, and shipped to market. Up until the 1960s the double-wall incubation rooms had been quite primitive and required constant attention; heat was provided by a charcoal fire or electric heater and humidity was controlled by a boiling pot of water. The new rooms had sophisticated control panels and automatically controlled temperature and humidity. One part by weight of raw soybeans yielded 1.8-2.0 parts of finished natto. In each gram of natto there are approximately 10,000,000 living natto bacteria, plus the enzymes they produce. Investigations by Ishima (Iishima??) and Ohta (1979 Ref??) showed that the most important sensory or organoleptic characteristics of good natto, in descending order of importance, were taste, appearance, and viscosity. The latter was ascribed to the formation of glutamic acid polymers.

Natto production and consumption in Japan expanded steadily during the postwar period (Table ??.?). According to Ebine (1968) and Ohta (1969), in 1968 there were about 1,600 natto manufacturers in Japan, and they produced roughly 80,000 tons of natto. The nationwide per capita consumption was estimated at 760-789 grams per year. The highest consumption was in the northeast prefectures, with an annual per capita consumption of 2,400 grams. The corresponding figure was 1,200-1,800 grams for Hokkaido and for the Tokyo area (Kanto), but less than 600 grams for the Kyoto-Osaka area (Kansai) and for Kyushu.

Official Japanese government statistics, compiled by the Ministry of Agriculture, Forestry, and Fisheries, show that natto production in Japan, from 1958 to 1982, grew at the average compound rate of 6.2% a year. This is impressive, especially when we consider that per capita consumption of Japan's two other major fermented soyfoods, shoyu (soy sauce) and miso, have declined during this period. Equally promising, the second-largest annual production increase in postwar history took place in the most recent year (1982), an increase of 16,000 tonnes, or 10.4%. Major reasons for this increase were (1) The growing reevaluation in Japan of the nutritional value of traditional soyfoods; (2) The growing interest in natural foods; and (3) the expansion of natto consumption in western Japan. Dampening the growth was the simultaneous steady Westernization of the Japanese diet, which slowed however after the early 1980s.

Nevertheless, per capita natto consumption is still relatively small, only 1.4 kg a year in 1982, compared with about 12 kg for shoyu and 6 kg for miso.


Natto Population Per Capita Consumption of Japan Natto

Year (Metric Tons) (Million) Consumption (kg/yr)

Metric Tons
1958 39,000 91.77 0.42
1959 41,000    
1960 42,000 93.42 0.45
1961 43,000    
1962 47,000    
1963 47,000    
1964 54,000    
1965 59,000 98.28 0.60
1966 68,000    
1967 85,000 100.20 0.85
1968 99,000    
1969 108,000    
1970 115,000 103.72 1.11
1971 115,000    
1972 122,000 107.60 1.13
1973 122,000    
1974 124,000 110.57  
1975 122,000 111.94 1.09
1976 124,000    
1977 130,000    
1978 135,000    
1979 142,000    
1980 153,000 117.06 1.30
1981 153,000    
1982 169,000 119 est    1.42

Source : Norin Suisansho Shokuhin Yushi-ka; or Sorifu no Kakei Chosa, Tokei Kyokyoku 1983.

Note: It is not clear whether or not these statistics include Hamanatto and Daitokuji natto (soy nuggets, both mold-fermented and salted). But even if they do, the latter would comprise less than 5% of the total.



While production was growing, the number of commercial manufacturers and the number of workers dropped, reflecting the rise of a new generation of large modern natto factories. In 1980 there were 1,037 manufacturers in Japan (there were 60 in Tokyo alone), and they employed 5,000 workers. In 1976 the ex-factory value of Japan's natto was US$ 228 million. The largest plant (Okame Natto Factory in Ifioka, Ibaragi prefecture) produced 3,000 metric tons of natto a year. The average Tokyo retail price was US $0.83 a pound. Prefectures and their leading centers with the highest annual per capita natto consumption in 1981 were Ibaragi prefecture (Mito 9,312 gm), Miyagi prefecture (Sendai 6,427 gm), Tochigi prefecture (Utsunomiya 5,179 gm), and Hokkaido (Sapporo 4,110 gm). Large amounts were also consumed in Fukushima and Aomori prefectures and in Tokyo. Note that all these areas are north of Tokyo. Natto continues to sell best during the winter months and more slowly during the summer; tofu is just the opposite.

Among scientists there is continued research and discussion concerning natto's medical and healing value. In 1967 Dr. Kameda (Ref??) of Kanazawa University Medical School injected cancer cells into both legs of 15 white rats and then injected natto bacteria into one leg of each rat. In each case the leg injected with natto showed no cancer development. Natto contains dipicolinic acid ( zibicolin in Japanese), a substance first discovered in natto and later found in all bacterial cells. It is said to bind heavy metals (such as radioactive strontium) and expel them from the body, thus making natto a food to ameliorate the effects of radioactivity. In Daizu Shokuhin ("Soyfoods") (1971), Dr. Ohta of the Japanese National Food Research Institute summed up the issue as follows: "Although there is much tentative evidence and basic research to the effect that natto is helpful in the prevention and cure of such contagious diseases as dysentery and intestinal typhus, it is still uncertain among medical specialists whether natto can prevent food poisoning or intestinal ailments, or whether it is of value as a convalescent dietary food." Little?? is known about the ability of the natto fermentation to reduce the flatulence factors in whole soybeans; if they are reduced, this would make natto much easier to digest than whole soybeans. It is known that the natto enzymes are potent, since commercial protease enzymes are now often produced from cultures of Bacillus natto .

During the 1970s, a number of new natto products were developed. These included: (1) Natto with Almonds. 10-15% finely diced almonds were added to natto to give an almond flavor and reduce the strong natto smell. Sold in 50 gm and 100 gram sizes, the product was considerably more expensive than regular natto; (2) Smoked Natto Dusted with Wheat Bran. The finished natto were rolled in wheat bran (to eliminate stickiness), then smoked (to give a savory flavor); (3) Calcium Fortified Natto . Used in some school lunch programs; (4) Natto with Chlorella. Made by mixing this microalga rich in protein and vitamin B-12 with natto; (5) Natto with Kombu, a sea vegetable, which is slivered; (6) Barley Natto and Brown Rice Natto. Although no soybeans are used, barley or brown rice are cooked in the liquid left over after cooking soybeans for regular natto. The grains are then incubated like soy natto; the soybean liquid gives the product a stringy consistency, but it has no natto smell yet a light taste that is nice for bread-based breakfasts. Introduced in about 1980.

At least one restaurant in Japan specialized in natto cuisine. The Hotel Sun Route, owned by Mr. Isamu Naraoka, served only natto recipes; the repertoire of 300 dishes took Mr. Naraoka some 10 years to develop.


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