Natto: Japan's unique fermented soybean delicacy

What is natto and how is it made?

Natto is a traditional Japanese dish made from fermented soybeans. The production process involves soaking whole soybeans in water, steaming them, and then fermenting them with a specific strain of bacteria called Bacillus subtilis var. natto. This fermentation process typically takes 24 to 36 hours and results in the characteristic sticky, stringy texture that natto is known for.

The commercial production of natto has evolved over time. In modern facilities, the process is carefully controlled to ensure consistency and quality. After the soybeans are cooked, they are inoculated with the natto bacteria and placed in small containers for fermentation. The temperature and humidity are closely monitored to create the ideal environment for the bacteria to thrive. Once the fermentation is complete, the natto is cooled and aged in a refrigerator to develop its full flavor and texture.

Interestingly, natto can also be made at home. Some families in Japan still practice the traditional method of wrapping cooked soybeans in rice straw, which naturally contains the natto bacteria. However, most home producers now use starter cultures and modern equipment to create their own natto.

The history and origins of natto

The exact origins of natto are somewhat unclear, but it is believed to have been developed in Japan over a thousand years ago. One popular legend attributes the discovery of natto to Minamoto no Yoshiie, a famous samurai who lived in the 11th century. According to the story, Yoshiie's troops were attacked while boiling soybeans for their horses. They quickly packed the beans in straw bags, and when they opened them a few days later, they found the beans had fermented into natto.

Another theory suggests that natto may have been influenced by similar fermented soybean foods from China, such as douchi. The fermentation of soybeans has a long history in East Asia, and it's possible that the technique spread to Japan and evolved into the unique product we know as natto today.

Regardless of its exact origins, natto became an important part of Japanese cuisine during the Heian Period (794-1185) and has remained popular ever since. The commercialization of natto production in the early 20th century, during the Taisho Period, led to more consistent and widely available natto, further cementing its place in Japanese food culture.

Opening a pack of wara natto

Nutritional benefits and health properties of natto

Natto is renowned for its impressive nutritional profile and potential health benefits. It is rich in protein, fiber, vitamins, and minerals, making it a nutritional powerhouse. Here are some of the key nutrients found in natto:

• Protein: Natto is an excellent source of plant-based protein, containing all essential amino acids.
• Vitamin K2: Natto is one of the richest dietary sources of vitamin K2, which is important for bone health and blood clotting.
• Probiotics: The fermentation process creates beneficial bacteria that can support gut health.
• Fiber: Natto is high in dietary fiber, which aids digestion and promotes feelings of fullness.
• Minerals: It contains significant amounts of iron, calcium, magnesium, and zinc.
• Vitamin C: Unlike many other soy products, natto retains its vitamin C content due to the fermentation process.

The health benefits associated with natto consumption are numerous. Research has suggested that regular natto intake may contribute to stronger bones, improved cardiovascular health, and enhanced digestive function. The high vitamin K2 content is particularly noteworthy, as it may help prevent osteoporosis and reduce the risk of heart disease. Additionally, the enzyme nattokinase, produced during fermentation, has been studied for its potential to dissolve blood clots and lower blood pressure.

How to eat natto: serving suggestions and popular combinations

In Japan, natto is most commonly eaten for breakfast, typically served over a bowl of steamed rice. However, there are many ways to enjoy this versatile food. Here are some popular serving suggestions:

• Traditional style: Mix natto with the provided soy sauce and mustard, then serve over hot rice. Add chopped green onions for extra flavor.
• Natto sushi: Roll natto in sushi rice and nori seaweed to make nattomaki.
• Natto toast: Spread natto on toast for a quick and easy breakfast or snack.
• In miso soup: Add natto to your miso soup for an extra protein boost.
• With pasta: Toss natto with spaghetti for a unique fusion dish.
• In salads: Mix natto into your favorite salad for added texture and nutrition.

For those new to natto, starting with smaller portions and gradually increasing the amount can help in acquiring a taste for it. Experimenting with different condiments and accompaniments can also make natto more palatable for beginners.

The taste, texture, and smell of natto: an acquired taste

Natto is often described as an acquired taste, primarily due to its unique sensory characteristics. The flavor of natto is complex, with notes of earthiness, nuttiness, and umami. Some people compare it to strong cheese or aged meat. The texture is perhaps the most distinctive aspect of natto - it's sticky and slimy, with long, stringy strands that form when the beans are stirred.

The aroma of natto is another factor that can be challenging for some. It has a strong, pungent smell that has been likened to ammonia or old socks. This odor comes from the compounds produced during fermentation, including diacetyl and pyrazines.

While these characteristics may seem off-putting to some, many people who grow up eating natto or who give it a chance find that they develop a taste for it over time. In fact, a 2009 survey revealed that 70% of Japanese people find the taste of natto pleasant. For those who struggle with the taste or texture, there are milder varieties available, as well as dried or fried natto products that have a less intense flavor and aroma.

Wara natto on sale in Kairaku-en Park, Mito, Ibaraki Prefecture

Regional popularity and variations of natto in Japan

While natto is enjoyed throughout Japan, its popularity varies by region. It is particularly beloved in eastern Japan, including the Kanto, Tohoku, and Hokkaido regions. In these areas, natto is a common breakfast food and is widely available in supermarkets and convenience stores.

The city of Mito in Ibaraki Prefecture is particularly famous for its natto. Known as the "Mito - the Natto Capital," this city has a long history of natto production and is home to several renowned natto manufacturers. Visitors to Mito can find a wide variety of natto products, including the traditional Mito Wara Natto, which is fermented in rice straw wrappings.

Regional variations of natto exist throughout Japan, with different areas having their own unique preparation methods and serving styles. For example:

• In Hokkaido, natto is often served with squid ink for a distinctive black color.
• In some parts of western Japan, natto is mixed with okra for added texture.
• In Kumamoto, you can find "hikiwari natto," made from crushed soybeans.

Natto production: commercial vs. homemade methods

Natto production has evolved significantly over the years, from traditional homemade methods to large-scale commercial operations. Let's explore both approaches:

Commercial Production:

Modern Mass Production Natto Today involves sophisticated equipment and carefully controlled environments. The process typically includes:

• Washing and soaking soybeans
• Steaming the beans in large pressure cookers
• Inoculating the cooked beans with B. subtilis natto bacteria
• Packaging the inoculated beans in sterile containers
• Fermenting under controlled temperature and humidity
• Cooling and aging the natto

Companies like Takano Foods have industrialized this process, producing millions of natto packages daily. These mass-produced natto packages often come with small sachets of soy sauce and mustard for flavoring.

A container of Takano Food Okame Natto. Packs of soy sauce and karashi mustard are inside of each container

Homemade Methods:

While less common today, some people still make natto at home. Traditional methods involve:

• Cooking soybeans
• Wrapping them in rice straw (which naturally contains natto bacteria)
• Fermenting in a warm place for 24-48 hours

Modern home production might use a store-bought natto as a starter culture or use specialized natto spores. Some enthusiasts use kitchen appliances like yogurt makers or instant pots to maintain the right fermentation temperature.

Whether commercially produced or homemade, natto remains an important part of Japanese cuisine and culture. Its unique flavor, texture, and health benefits continue to intrigue food lovers and health enthusiasts around the world.