Nattō

Nattō(納豆)is a traditionalJapanese foodmade from wholesoybeansthat have beenfermentedwithBacillus subtilisvar.natto.It is often served as a breakfast food with rice.It is served withkarashimustard,soyortaresauce, and sometimesJapanese bunching onion. Within Japan,nattōis most popular in the eastern regions, includingKantō,Tōhoku, andHokkaido.
Nattōis often considered anacquired tastebecause of its powerful smell, strong flavor, and sticky, slimy texture.A 2009 survey revealed that 70% of Japanese people find the taste pleasant, and others who may not find the taste  pleasant still eat the food out of habit.
Sources differ about the earliest origin ofnattō. One theory is that nattō was codeveloped in multiple locations in the distant past, since it is simple to make with ingredients and tools commonly available in Japan since ancient times.
One story about the origin ofnattōattributes it to the samuraiMinamoto 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 involvesPrince 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.
Beforenattō, there was a similar dish of fermented black soybeans food in China called (Chinese:豉;pinyin:Shì) (chǐ) ordouchi(Chinese:豆豉;pinyin:dòuchǐ). 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 producedouchi. The amount of salt used also differentiatesdouchiandnattōin taste and appearance.
The cultivation methods of soybeans and rice were imported from China to Japan during theYayoi period, and later on, the circulation of salt began to flourish in Japan. This provided an opportunity for the production ofdouchito become popular in Japan. Because salt was expensive at the time, it has been suggested thatnattōwas invented by accident during the production ofdouchi.
A wooden slip was excavated inHeijō-kyō, which had the Chinese character 豉 (chǐ; soybean) written on it.The excavation of the slip is considered an evidence to support the hypothesis that the invention ofnattōwas based on the Chinesedouchiimported to Japan.
The Chinese character 豉 entered Japan in the 8th century. It was pronounced "kuki" until the 11th century, whennattōbecame a new name for fermented soybeans.
A change in the production ofnattōoccurred in theTaishō period(1912–1926), when researchers discovered a way to produce anattōstarter culturecontainingBacillus subtiliswithout the need for straw, thereby simplifying the commercial production ofnattōand enabling more consistent results.
Nattō is 55% water, 13%carbohydrates, 19%protein, and 11%fat(table). In a 50 grams (1.8 ounces) serving, nattō supplies 110caloriesand is a rich source (20% or more of theDaily Value, DV) of severaldietary minerals, especiallyiron(33% DV) andmanganese(73% DV), andvitamin K(542% DV). Nattō contains someB vitaminsandvitamin Cin moderate amounts (table).
Nattōhas a distinctive odor, somewhat akin to a pungent aged cheese. Stirringnattōproduces many sticky strings.The dish is eaten cold with rice, mixed with the included soy sauce orkarashimustard if eaten from a commercially packagednattō. Other ingredients such as long onion orkimchiare often added.
Nattōis frequently eaten asnattōgohan(nattōon rice).Nattōis occasionally used in other foods, such asnattōsushi (nattōmaki),nattōtoast, inmiso soup,tamagoyaki, salad, as an ingredient inokonomiyaki,chahan, or even withspaghetti. Sometimes soybeans are crushed before fermenting.
Many find the taste unpleasant and smelly while others relish it as a delicacy. Nattō is more popular in some areas of Japan than in others.Nattōis known to be popular in the easternKantō region, but less popular inKansai.
For those who dislike the smell and texture of natto, "dried natto" and "fried natto" were developed around 1990. The smell and stickiness are reduced, making it easier to eat for those who do not like conventional natto. Another type of fermented soybeans calledmamenoka(Japanese:豆乃香) has also been developed by improving the soybean and natto bacillus varieties to make it less sticky.
Nattōis made from soybeans, typicallynattōsoybeans. 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 aresteamedfor six hours, although apressure cookermay be used to reduce the time. The cooked beans are mixed with the bacteriumBacillus subtilis, known asnattō-kinin Japanese. From this point on, care must be taken to keep the ingredients away from impurities and otherbacteria. The mixture is fermented at 40 °C (104 °F) for up to 24 hours. Afterward, thenattōis cooled, then aged in a refrigerator for up to one week to allow the development of stringiness.
Innattō-making facilities, these processing steps have to be done while avoiding incidents in which soybeans are touched by workers. Even though workers useB. subtilis nattoas the starting culture, which can suppress some undesired bacterial growth, workers pay extra-close attention not to introduceskin floraonto soybeans.
Nattōcontinues 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 fornattō, which is a less finicky culture capable of sustaining its own ideal temperature once it gets going.
Mass-producednattōis sold in smallpolystyrenecontainers. A typical package contains two, three, or occasionally four containers, each 40 to 50 g (1.4 to 1.8 oz). One container typically complements a small bowl of rice.
Nattōodor comes fromdiacetylandpyrazines, but if it is allowed to ferment too long, thenammoniais released.
The fermenting ofnattōdevelopsglutamic acid, which is why it has anumamiflavour.
Many countries around Asia also produce similar traditional soybean foods fermented withBacillusbacteria, such asshuǐdòuchǐ(水豆豉) ofChina,cheonggukjang(청국장) ofKorea,thua nao(ถั่วเน่า) ofThailand,kinemaofNepaland theHimalayanregions ofWest BengalandSikkim,tungrymbaiofMeghalaya,hawaijaarofManipur,bekang umofMizoram,akhuniofNagaland, andpiakofArunachal Pradesh,India.