Few foods polarize palates as cleanly as natto, the slimy, fragrant fermented soybeans that anchor a classic Japanese breakfast. For the uninitiated, the sticky strings and pungent ammonia notes can be intimidating, yet for millions in Japan, natto is a non-negotiable part of the day, a savory powerhouse believed to deliver energy and vitality before the workday even begins.
What is Natto and How is it Made?
Natto is simply soybeans that have been steamed, inoculated with the specific bacterium Bacillus subtilis, and then fermented at a warm temperature for roughly 24 hours. This controlled fermentation is what creates the beans' signature sticky texture and deep umami flavor, transforming the humble soybean into a completely different ingredient. The process is closely monitored to ensure the right balance of viscosity and flavor, resulting in a product that is simultaneously tender and stringy.
The Science Behind the Slime
The distinctive stickiness of natto is caused by a polysaccharide called poly-gamma-glutamic acid (γ-PGA), which is produced by the Bacillus subtilis bacteria during fermentation. This compound acts as a natural thickener and is also found in other fermented foods like Japanese nattō-maki. Beyond the texture, this fermentation process also breaks down the soybeans' complex sugars and proteins, making the nutrients more bioavailable and creating the unique, slightly bitter, and nutty flavor profile that defines the dish.
Health Benefits and Nutritional Profile
Natto is frequently celebrated as a functional food, largely due to its high vitamin K2 content, which is crucial for bone and cardiovascular health by helping to direct calcium to the right places in the body. It is also an excellent source of high-quality plant-based protein, dietary fiber, and several B vitamins. The fermentation process generates a powerful enzyme called nattokinase, which has been studied extensively for its potential benefits in supporting healthy blood circulation and maintaining balanced blood pressure.
Key Nutritional Components
Culinary Traditions and Modern Usage
In Japan, natto is most commonly enjoyed over steamed rice, a combination that balances the strong flavor of the beans. It is typically topped with finely chopped green onions, Japanese mustard (karashi), and a drizzle of soy sauce or tsume (a sweet bonito broth). While it remains a staple of traditional breakfast menus, its use has evolved, appearing today in burgers, pasta sauces, and even as a thickening agent for soups, showcasing its versatility beyond the traditional bowl of rice.
How to Approach Eating Natto
For the first-time eater, the key to enjoying natto is to embrace the process rather than focusing on the immediate texture. Start with a small amount mixed into hot rice; the heat helps to mellow the flavor and loosen the strings. Chew thoroughly to experience the full transformation of the beans into a creamy, savory paste. Rather than fighting the stickiness, view it as an indicator of the active enzymes and probiotics that make the food so distinctive.
