Nattō - WikiHQ

is a traditional Japanese food made from whole soybeans that have been fermented with Bacillus subtilis var. natto.

Nattō is often considered an acquired taste because of its powerful smell, strong flavor, and sticky, slimy texture.

Legendary origins

thumb|Opening and stirring a container of nattō

One story about the origin of nattō attributes it to the samurai Minamoto no Yoshiie (1039–1106), who was on a campaign in northeastern Japan between 1086 and 1088 AD. One day, his troops 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.

Another story involves Prince Shotoku (574–622), who is said to have wrapped the leftovers of boiled soybeans in straw bags for his horse. As people happened to eat these fermented beans and found them delicious, this type of fermented stringy beans soon gained popularity in Japan because of its unique taste and strong flavor.

Chinese douchi

Before nattō, there was a similar dish of fermented black soybeans food in China called shì, chǐ (), or douchi (). These are salted, fermented and aged whole soybean seasonings or condiments invented in China and spread throughout East Asia. They are usually made from fermented soybeans and with an ample amount of salt; however, the ingredients and production methods differ in Japan. Chinese use both black and yellow soybeans to produce douchi. The amount of salt used also differentiates douchi and nattō in taste and appearance.

The cultivation methods of soybeans and rice were imported from China to Japan during the Yayoi period, and later on, the circulation of salt began to flourish in Japan. This provided an opportunity for the production of douchi to become popular in Japan. Because salt was expensive at the time, it has been suggested that nattō was invented by accident during the production of douchi.

Nutrition

Nattō is 55% water, 13% carbohydrates, 19% protein, and 11% fat (table). In a serving, nattō supplies 110 calories and is a rich source (20% or more of the Daily Value, DV) of several dietary minerals, especially iron (33% DV) and manganese (73% DV), and vitamin K (542% DV). Nattō contains some B vitamins and vitamin C in moderate amounts (table).

Appearance and consumption

thumb|Nattō with strands

Nattō has a distinctive odor, somewhat akin to a pungent aged cheese. Stirring nattō produces many sticky strings.

Production process

Commercial

thumb|Nattō is historically wrapped in rice straw

thumb|A nattō bean-size legend using beans before fermentation in a supermarket

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 hydrate them, and increase their size. Next, the soybeans are steamed for six hours, although a pressure cooker may be used to reduce the time. The cooked beans are mixed with the bacterium Bacillus subtilis, known as nattō-kin in Japanese. From this point on, care must be taken to keep the ingredients away from impurities and other bacteria. The mixture is fermented at 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.

In nattō-making facilities, these processing steps have to be done while avoiding incidents in which soybeans are touched by workers. Even though workers use B. subtilis natto as the starting culture, which can suppress some undesired bacterial growth, workers pay extra-close attention not to introduce skin flora onto soybeans.

Home

Nattō continues to be a popular home fermentation activity with some families starting new batches daily. Home production was historically done using rice straw to maintain moisture and as insulation with placement in naturally warmer parts of the home or fermentation shed, but is now done with moist towels over glass pans or perforated plastic wrap on thermostat-controlled heating pads. At-home fermentation machines are also available but are rarely marketed specifically for nattō, which is a less finicky culture capable of sustaining its own ideal temperature once it gets going.

End product

thumb|Nattō is usually sold in small containers.

Mass-produced nattō is sold in small polystyrene containers. A typical package contains two, three, or occasionally four containers, each . One container typically complements a small bowl of rice.

Nattō odor comes from diacetyl and pyrazines, but if it is allowed to ferment too long, then ammonia is released.

The fermenting of nattō develops glutamic acid, which is why it has an umami flavour.

alt=KNT (Kinema-Natto-Thua Nao) triangle|thumb|The KNT (Kinema–Natto–Thua Nao) triangle connects the fermented soyabeans across [[Asia.]]

Many countries around Asia also produce similar traditional soybean foods fermented with Bacillus bacteria, such as shuǐdòuchǐ (水豆豉) of China, cheonggukjang (청국장) of Korea, thua nao (ถั่วเน่า) of Thailand, kinema of Nepal and the Himalayan regions of West Bengal and Sikkim, tungrymbai of Meghalaya, hawaijaar of Manipur, bekang um of Mizoram, akhuni of Nagaland, and piak of Arunachal Pradesh, India.