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Nattō (なっとう or 納豆) is a traditional Japanese food made from soybeans fermented with Bacillus subtilis. It is popular especially as a breakfast food. As a rich source of protein, nattō and the soybean paste miso formed a vital source of nutrition in feudal Japan. Nattō may be an acquired taste because of its powerful smell, strong flavor, and slimy texture. In Japan nattō is most popular in the eastern regions, including Kantō, Tōhoku, and Hokkaido.
Sources differ about the earliest origin of nattō. The materials and tools needed to produce nattō commonly have been available in Japan since ancient times; one source puts the first use of nattō in the Jōmon period (10,000–300 BC). According to other sources the product may have originated in China during the Zhou Dynasty (1134-246 BC). There is also the story about Minamoto no Yoshiie who was on a battle campaign in northeastern Japan between 1086 AD and 1088 AD when one day they were attacked while boiling soybeans for their horses. They hurriedly packed up the beans, and did not open the straw bags until a few days later, by which time the beans had fermented. The soldiers ate it anyway, and liked the taste, so they offered some to Yoshiie, who also liked the taste. A third source places the origin of nattō more recently, in the Edo period (1603–1867). It is even possible that the product was discovered independently at different times.
One significant change in the production of nattō happened in the Taishō period (1912–1926), when researchers discovered a way to produce a nattō starter culture containing Bacillus natto without the need for straw. This simplified production and permitted more consistent results.
Appearance and consumption 
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The first thing one notices after opening a pack of nattō is its distinctive smell, somewhat akin to a pungent cheese.[original research?] Stirring the nattō produces lots of sticky strings. The nattō strings themselves are often described by the Japanese ideophone nebaneba, which roughly translates as 'viscid' or 'gooey'. The flavor of nattō is nutty, savory, and slightly salty.
Nattō commonly is eaten at breakfast to accompany rice, possibly with soy sauce, tsuyu broth, mustard, scallions, grated daikon, okra, or a raw egg. In Hokkaidō and the northern Tōhoku region, some people dust nattō with sugar.[original research?] Nattō frequently is used in other foods, such as nattō sushi, nattō toast, in miso soup, tamagoyaki, salad, as an ingredient in okonomiyaki, or even with spaghetti. A dried form of nattō, having little odor or sliminess, may be eaten as a nutritious snack. There is even nattō ice cream. Sometimes soybeans are crushed and fermented. This is called 'hikiwari nattō'. It is a food that is easy to digest.
The perceived flavor of nattō can differ greatly between people; some find it has a strong and cheesy taste and they may thus use it in small amounts to flavor rice or noodles, while others find it tastes bland and unremarkable, requiring the addition of flavoring condiments such as mustard and soy sauce.[original research?] Many non-Japanese find the taste unpleasant and smelly, while others relish it as a delicacy. Some manufacturers produce an odorless or low-odor nattō.
Nattō is more popular in some areas of Japan than in others. Nattō is known to be popular in the eastern Kantō region, but less popular in Kansai. 236,000 tons of nattō are consumed in Japan each year. A 2009 internet survey in Japan indicated 70.2% of respondents like Natto and 29.8% do not, but out of 29.8% who dislike Natto, about half of them eat natto for its health benefits.
Production process 
Nattō is made from soybeans, typically nattō soybeans. Smaller beans are preferred, as the fermentation process will be able to reach the center of the bean more easily. The beans are washed and soaked in water for 12 to 20 hours to increase their size. Next, the soybeans are steamed for 6 hours, although a pressure cooker may be used to reduce the time. The beans are mixed with the bacterium Bacillus subtilis natto, known as nattō-kin in Japanese. From this point on, care must to be taken to keep the ingredients away from impurities and other bacteria. The mixture is fermented at 40 °C (104 °F) for up to 24 hours. Afterward the nattō is cooled, then aged in a refrigerator for up to one week to allow the development of stringiness. During the aging, at a temperature of about 0 °C, the bacilli develop spores, and enzymatic peptidases break down the soybean protein into its constituent amino acids.
In Natto making faculties, these processing steps have to be done by avoiding incidents which soy beans are touched by workers. Even though workers use Bacillus subtilis natto as the starting culture which can suppress some of other undesired bacterial growth, workers pay an extra- close- attention not to introduce skin flora onto soy beans. 
Historically, nattō was made by storing the steamed soybeans in rice straw, which naturally contains B. subtilis natto. The soybeans were packed in straw and left to ferment. The fermentation was done while the beans were buried underground beneath a fire or stored in a warm place in the house, for example under the kotatsu.
Regardless of the process, Japanese manufacturers need permission from the prefectural government, as required by food sanitation law.
End product 
Today's mass-produced nattō is sold in small polystyrene containers. A typical package contains two, three, or occasionally four containers, each 40 to 50 g. One container typically complements a small bowl of rice. It usually includes a small packet of soy sauce and another packet of karashi, a type of mustard. Other condiments to accompany the nattō, such as shiso, also are available.
Sometimes outside of Japan, frozen nattō is sold that must be thawed before consumption.
To make nattō at home, you need a bacterial culture of B. subtilis. B. subtilis nattō is weak in lactic acid, so it is important to prevent lactic acid bacteria from breeding. Some B. subtilis nattō varieties that are more odorless are usually less active, raising the possibility that minor germs will breed. Bacteriophages are dangerous to B. subtilis. After a bacteriophage has infected a B. subtilis colony, minor germs may breed in the soybeans, particularly in boiled soybeans.
Natto has a different nutritional makeup from when it was raw soy beans, losing Vitamin A, and other Vitamins and minerals compared to raw soy beans. However, calories in Natto are lower than in raw soy beans. Soy beans are highly nutritious, however the nutrition is packed in hard fiber. Natto has the benefit of nutritious soy and softer dietary fiber without too much sodium, which is present in high concentrations in other soy products like miso. Natto contains no cholesterol, almost no sodium, but is a significant source of iron, calcium, magnesium, protein, potassium, vitamin B6, B2, E, K2 and more.   When Natto is mixed with egg and eaten with rice, Japanese call the dish a perfectly nutritious meal, covering all nutrition needs.
When Bacillus subtilis natto breaks up soy protein, the bacteria creates chains of polyglutamic acid, Gamma polyglutamic acid. The unique part of this polypeptide chain is that the peptide bond is between Nitrogen and R-group’s carboxyl acid.
Health Benefits 
The Japanese media frequently claim, especially in television shows for health-concerned viewers, that nattō is health-enhancing and that these claims are backed by medical research.[original research?]
One example is pyrazine: Pyrazine is a compound that, in addition to giving nattō its distinct smell, reduces the likelihood of blood clotting. It also contains a serine protease type enzyme called, nattokinase which also may reduce blood clotting both by direct fibrinolysis of clots, and inhibition of the plasma protein plasminogen activator inhibitor 1. This may help to avoid thrombosis, as for example in heart attacks, pulmonary embolism, or strokes.
An extract from nattō containing nattokinase is available as a dietary supplement. Studies have shown that oral administration of nattokinase in enteric capsules leads to a mild enhancement of fibrinolytic activity in rats and dogs. It is, therefore, plausible to hypothesize that nattokinase might reduce blood clots in humans—although clinical trials have not been conducted. Another study suggests that Fibrinolysis Accelerating Substance (FAS) in natto is the substance which initiates fibrinolysis of clots, which accelerates the activity of not only nattokinase, but urokinase.
A 2009 study in Taiwan indicated that the nattokinase in natto has the ability to degrade amyloid fibrils, suggesting that it might be a preventative or a treatment for amyloid-type diseases such as Alzheimer's.
Natto is rich in vitamin K. It contains large amounts of vitamin K2, which is involved in the formation of calcium-binding groups in proteins, assisting the formation of bone and preventing osteoporosis. Vitamin K1 is found naturally in leafy greens, seaweed, liver, and some vegetables, while vitamin K2 (Menatetrenone) is found in fermented food products such as cheese, miso, and Nattō. Nattō has large amounts of vitamin K2, approximately 870 micrograms per 100 grams of nattō.
According to recent studies, polyamine suppresses excessive immune reactions, and nattō has a much larger amount of it than any other food. Dietary supplements containing the substances extracted from natto such as polyamine, nattokinase, FAS, and vitamin K2 are available.
Nattō contains chemicals alleged to prevent cancer, for example, daidzein, genistein, isoflavone, phytoestrogen, and the chemical element selenium, however, most of these chemicals also may be found in other soybean products, and their effect on cancer prevention is uncertain.
Nattō is claimed to prevent obesity, possibly because of its low calorie content of approximately 90 calories per 7–8 grams of protein in an average serving. Unverified claims include improved digestion, reduced effects of aging, and the reversal of hair loss in men due to its phytoestrogen content, which can affect testosterone associated with baldness. These conjectured physiological effects of eating natto are based on biochemically active contents of nattō, and have not been confirmed by human study.
Ecological use 
Natto’s polyglutamic acid is useful as an organic polymer coagulant. Polyglutamic acid is useful in making organic and inexpensive water cleaner products, PGα21Ca, sold as a powder.
Similar foods 
Many countries produce similar traditional soybean foods fermented with Bacillus subtilis, such as shuǐdòuchǐ (水豆豉) of China, cheonggukjang (청국장) of Korea, thuanao (ถั่วเน่า) of Thailand, kinema of Nepal and the Himalayan regions of West Bengal and Sikkim, hawaijaar of Manipur, akhuni of Nagaland, piak of Arunachal Pradesh, India. In addition certain West African bean products are fermented with the bacillus, including dawadawa, sumbala, and iru, made from néré seeds or soybeans, and ogiri, made from sesame or melon seeds.
Methods of eating nattō differs from region to region. Nattō is eaten with rice, with curry, Chinese noodles, Japanese style pasta, and tempura.
Natto dishes 
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Salted nattō is a local dish in the Kouchi prefecture of Japan. Salt is sprinkled over nattō, and roasted nuka (powdered rice bran) is added in the pan. In the traditional recipe, the nattō soybeans are steamed with momigara (rice chaff).
Stamina nattō is nattō mixed with minced chicken, then stir-fried in sesame oil, ginger, garlic and Tabasco. It is served with the school lunch in the Tottori prefecture.
Nattō Ae is nattō mixed with cheese, soy sauce, parsley, and sugar. It is served with the school lunch in the city of Toyota in the Aichi prefecture of Japan.
Nattō-jiru is a kind of miso soup, which consists of nattō and vegetables and popular in the Tohoku area.
Nattō-maki is a kind of sushi roll.
Soboro-nattō is a speciality in Ibaraki, mixing nattō and kiriboshi-daikon (cut and dried daikon raddish), seasoned with soy sauce.
Hoshi-nattō (sun dried nattō) is an Ibaraki speciality which can be stored for long time. This is eaten as is, or eaten as Chazuke. Originally, hoshi-nattō is a preserved food. It is often eaten by Japanese when away from Japan.
Age-nattō (fried nattō) looks simillar to hoshi-nattō. This product is removed the stickiness by deep-frying and is seasoned with soy sauce and/or salt. The peculiar smell is lessened by this process. This is eaten as is or as a relish with alcohol.
Sakura-nattō is a popular dish in Kumamoto prefecture, which mixes nattō and raw horse meat (sakura-niku, lit.cherry meat) seasoned with soy sauce.
Nattō gunkan maki (Nattō sushi)
See also 
- Amanattō – is not nattō, but rather, beans sweetened with sugar
- Fermented bean paste
- Japanese cuisine – Other fermented soy foods include soy sauce, Japanese miso, Chinese dòuchǐ (fermented black soybeans), fermented tofu and (a subcategory) chòu dòufu (stinky tofu), Korean doenjang, Meju, and cheonggukjang, Nepalese kinema, and Indonesian tempeh and oncom.
- List of fermented soy products
- Hosking, Richard (1995). A Dictionary of Japanese Food - Ingredients and Culture. Tuttle. p. 106. ISBN 0-8048-2042-2.
- McCloud, Tina (7 December 1992). "Natto: A Breakfast Dish That's An Acquired Taste". Daily Press. Retrieved 25 December 2012. "It's a traditional soybean breakfast food from northern Japan and it's called natto. [...] As a breakfast food, natto is usually served over steamed rice and mixed with mustard and soy sauce."
- Katz, Sandor Ellix (2012). The Art of Fermentation: An In-Depth Exploration of Essential Concepts and Processes from Around the World. Chelsea Green Publishing. pp. 328–329. ISBN 978-1603582865. "Natto is a Japanese soy ferment that produces a slimy, mucilagenous coating on the beans, something like okra. [...] The flavor of natto carries notes of ammonia (like some cheeses or overripe tempeh), which gets stronger as it ferments longer."
- A., M. (30 March 2010). "Not the natto!". Asian Food. The Economist. Retrieved 25 December 2012. "... natto, a food that has achieved infamy among Japan's foreign residents."
- Buerk, Roland (11 March 2010). "Japan opens 98th national airport in Ibaraki". BBC News. Retrieved 25 December 2012. "... natto, a fermented soy bean dish that many consider an acquired taste."
- "Natto Fermented Soy Bean Recipe Ideas". Japan Centre. Retrieved 25 December 2012. "Natto are one of those classic dishes that people either love or hate. Like Marmite or blue cheese, natto has a very strong smell and intense flavour that can definitely be an acquired taste."
- "Preparing Nattou". Massahiro. Retrieved 28 March 2013. "Preparing Nattou step by step, without using rice straw."
- Shurtleff, W.; Aoyagi, A (2012). History of Natto and Its Relatives (1405-2012). Lafayette, California: Soyinfo Center.
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- National Cardiovascular Center (Suita, Osaka, Japan) HuBit genomix, Inc. (Chiyoda-ku, Tokyo, Japan; President and CEO: Go Ichien) NTT DATA Corporation (Koto-ku, Tokyo, Japan; President and CEO: Tomokazu Hamaguchi) Municipality of Arita, Saga Prefecture, Japan (Mayor: Masata Iwanaga) (April 2006). "Examining the Effects of Natto (fermented soybean) Consumption on Lifestyle-Related Diseases". Retrieved 2007-03-19.[dead link]
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