Nattō
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Nattō (納豆?) is a traditional Japanese food made from fermented soybeans, popular especially at breakfast. A rich source of protein, nattō and the soybean paste miso formed a vital source of nutrition in feudal Japan. Nattō is an acquired taste due to its powerful smell (which tends to leave its consumer with unpleasant breath), strong flavor and sticky consistency. In Japan nattō is most popular in the eastern Kanto region.
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[edit] Appearance and consumption
The first thing noticed by the uninitiated after opening a pack of nattō is the very strong smell, akin to strong cheese. Stirring the nattō produces lots of spiderweb-like strings. The nattō itself has a nutty, savory, somewhat salty flavor that belies its odor.
Nattō is most commonly eaten at breakfast to accompany rice, possibly with some other ingredients, for example soy sauce, tsuyu broth, mustard, scallions, grated daikon, okra, or a raw quail egg. In Hokkaido and northern Tohoku region, some people dust nattō with sugar. Nattō is also commonly used in other foods, such as nattō sushi, nattō toast, in miso soup, salad, as an ingredient in okonomiyaki, or even with spaghetti or as fried nattō. A dried form of nattō, having little odor or sliminess, can be eaten as a nutritious snack. There is even nattō ice cream.
Nattō is often considered an acquired taste and the perceived flavor of nattō can differ greatly between people; some find it tastes very strong and cheesy and may 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. Some manufacturers produce an odorless or low-odor nattō. The split opinion about its appearance and taste might be compared to Vegemite in Australia and New Zealand, haggis in Scotland, blue cheese in France, lutefisk in Norway and Sweden, and Marmite in the UK. Even in Japan, nattō is more popular in some areas than in others. Nattō is known to be popular in the eastern Kanto region (Tokyo), but less popular in Kansai (Osaka, Kobe). About 50,000 tons of nattō are consumed in Japan each year.
[edit] Production process
Nattō is made from soybeans, typically a special type called 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. This will increase the size of the beans. Next, the soybeans are steamed for 6 hours, although a pressure cooker can be used to reduce the time. The beans are mixed with a special sauce containing salt, sugar, and yeast and the rice straw bacterium Bacillus subtilis natto, known as nattō-kin in Japanese. Other ingredients may be added by some manufacturers. From this point on, care has to be taken to keep the ingredients away from impurities and other bacteria. The mixture is fermented at 40°C for up to 24 hours. Afterwards the nattō is cooled, then aged in a refrigerator for up to one week to add stringiness. During the aging process at a temperature of about 0°C, the Bacilli develop spores, and enzymatic peptidases break down the soybean protein into its constituent amino acids.
Historically, nattō was made by storing the steamed soy beans in rice straw, which naturally contains B. subtilis natto. The nattō was packed in straw and then left to ferment by itself. The fermentation was done either while the beans were buried underground underneath a fire or stored in a warm place in the house as for example under the kotatsu.
[edit] End product
Today's mass-produced nattō is usually sold in small polystyrene containers. A typical package contains 2 or 3 containers, occasionally 4 containers, each of 40 to 50 g. One container typically complements a small bowl of rice. It usually includes a small packet of tsuyu and another packet of karashi, a type of mustard. Other flavors of sauce, such as shiso, are available.
Mito City and Kumamoto Prefecture are famous as nattō-producing districts.
Outside of Japan, nattō is sometimes sold frozen, and must be thawed before consumption.
[edit] History
The materials and tools needed to produce nattō (soybeans and straw) were commonly available in Japan since ancient times, so the discovery could have happened as early as in the Jomon period. It may also be possible that the product was discovered independently by numerous people at different times. The sources differ about the earliest origin of nattō. One source puts the first use of nattō in the Jomon period between 10,000 and 300 BC. According to other sources the product may also have originated in China during the Zhou Dynasty (1134 - 246 BC). Another story is that Yoshiie Minamoto was on a battle campaign in northeastern Japan between 1056 and 1063 and another campaign between 1086 and 1088 when one day in 1083 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, at 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 calls the origin of nattō fairly recent from the Edo period (1603 to 1867).[citation needed]
One significant change in the production of nattō happened in the Taisho period (1912 - 1926), when researchers discovered a way to produce a nattō starter culture containing Bacillus natto without the need for straw. This greatly simplified the production process and enabled more consistent results.
[edit] Medical benefits
Nattō is claimed to have many medical benefits, and Japanese often say that eating nattō is good for your health. Some of these claims are backed by medical research. Nattō for example contains a compound Pyrazine, which not only gives nattō its distinct smell, but also reduces the likelihood of blood clotting. It also contains a serine protease type enzyme called nattokinase[1] which may also 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 leads to a mild enhancement of fibrinolytic activity in rats[2] and dogs. It is therefore plausible to hypothesize that nattokinase might reduce blood clots in humans, although clinical trials have not been conducted.
Nattō also contains large amounts of Vitamin K, 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 seaweed, liver and some vegetables, while vitamin K2 is found in fermented food products like cheese and miso. Nattō has very large amounts of vitamin K2, approximately 870 micrograms per 100 grams of nattō.
Nattō also contains many chemicals alleged to prevent cancer, as for example daidzein, genistein, infrabin, phytoestrogen, and the chemical element selenium. However, most of these chemicals can also be found in other soy bean products, and their effect on cancer prevention is uncertain at best. Some sources also claim that nattō has a cholesterol-lowering effect.[citation needed]
Nattō is also said to have an antibiotic effect, and was used as medicine against dysentery by the Imperial Japanese Army before World War II. Furthermore, nattō is said to improve digestion, reduce the effects of aging, and to prevent obesity (also possibly due to a low calorie content of approximately 90 calories per 7-8 grams of protein in an average serving), although this seems to be based only on an analysis of the chemicals contained in nattō, and not on any medical study.
Nattō is also sometimes used as an ingredient of pet food, and it is claimed that this improves the health of the pets.
Nattō is known to reverse hair loss in men due to phytoestrogens, which can lower testosterone that causes baldness.
[edit] Iron Chef Nattō Battle
Nattō was a theme ingredient in an episode of the Japanese hit television show Iron Chef. For details of that episode see Iron Chef Natto Battle.
[edit] See also
Other fermented soy foods include: Korean doenjang, Japanese miso, Chinese dòuchǐ (fermented black beans) & chòu dòufu (stinky tofu), and Indonesian tempeh. Note that amanatto is not nattō, but rather, beans sweetened with sugar.
The Korean fermented soybean product cheonggukjang is very similar to nattō.
[edit] References
- ^ Fujita M et al (December 1993). "Purification and characterization of a strong fibrinolytic enzyme (nattokinase) in the vegetable cheese natto, a popular soybean fermented food in Japan.". Biochemical and Biophysical Research Communications 197 (3): 1340-1347. PMID 8280151. Retrieved on 14 July 2006.
- ^ Fujita M, Hong K, Ito Y, Misawa S, Takeuchi N, Kariya K, Nishimuro S. (September 1995). "Transport of nattokinase across the rat intestinal tract.". Biological & pharmaceutical bulletin. 18 (9): 1194 - 1196. PMID 8845803. Retrieved on 14 July 2006.
