What Are Fermented Beans Called? Natto and More
What Are Fermented Beans?
Fermented beans are legumes, most commonly soybeans, that have undergone a controlled transformation process involving beneficial microorganisms. This process, known as fermentation, uses specific bacteria, yeasts, or molds to break down the complex compounds in the beans. The result is a food with enhanced flavor, improved digestibility, and often a significantly higher nutritional value than the raw bean.
The fermentation process works by converting proteins into amino acids, carbohydrates into simpler sugars, and fats into fatty acids. This not only creates the characteristic umami taste and distinct textures found in fermented bean products but also neutralizes anti-nutrients like phytic acid, which can block mineral absorption. The specific microorganism used—whether it is Bacillus subtilis for natto or Rhizopus oligosporus for tempeh—determines the final product's appearance, flavor, and nutritional profile.
The Role of Soybeans in Fermentation
While nearly any legume can be fermented, soybeans are the most common base due to their high protein content, healthy fat profile, and mild flavor that readily absorbs the character of the fermenting culture. Soybeans are a complete protein, meaning they contain all nine essential amino acids, making them an excellent foundation for nutrient-dense fermented foods. The fermentation process further enhances their nutritional value by producing bioactive compounds like vitamin K2 and nattokinase, which are not naturally present in raw soybeans.
Fermented Beans vs. Fermented Soy Products
It is important to distinguish between whole fermented beans and other fermented soy products. While natto and douchi involve fermenting the whole bean, other common foods like miso and soy sauce are made by fermenting soybeans but are typically processed into pastes or liquids. Tempeh, while made from soybeans, involves the beans being bound together by a mold mycelium into a solid cake. Understanding these differences helps clarify the specific answer to "what are fermented beans called" in different culinary contexts.
The Most Common Fermented Bean: Natto
When people ask "What are fermented beans called?" the most direct and common answer is natto. This traditional Japanese food is made by fermenting soybeans with the bacterium Bacillus subtilis. Natto is renowned for its strong, pungent aroma, slimy texture, and powerful nutritional profile. It is a staple breakfast food in Japan, often served over rice with soy sauce, mustard, and green onions.
Appearance, Taste, and Texture
Natto is immediately recognizable by its sticky, gooey texture. When stirred, the beans produce long, stringy threads of viscous material. The flavor is deeply savory and umami, with a slight bitterness and a pungent, fermented smell that many describe as an acquired taste. The texture can be off-putting to first-timers, but regular consumers appreciate it for its unique mouthfeel and the way it coats each grain of rice.
Nutritional Profile of Natto
Natto is one of the most nutrient-dense foods available. A single serving (about 100 grams) provides approximately 211 calories, 18 grams of protein, 11 grams of fat, and 14 grams of carbohydrates. It is exceptionally rich in vitamin K2, specifically the menaquinone-7 (MK-7) form, which is crucial for bone and cardiovascular health. Natto is also the only natural food source of nattokinase, a powerful enzyme with fibrinolytic activity that helps break down blood clots. Additionally, it contains high levels of fiber, iron, calcium, magnesium, and probiotics.
How Natto Is Made
The production of natto is a fascinating process that relies on precise conditions. Soybeans are first soaked overnight, then steamed (not boiled) until soft. They are then inoculated with Bacillus subtilis spores and incubated at a temperature of around 40°C (104°F) for 24 hours. During this time, the bacteria break down the soybean proteins into amino acids and produce the characteristic sticky substance, which is composed of polyglutamic acid and levan. After fermentation, the natto is cooled and aged for a day or two to develop its full flavor profile.
Other Fermented Beans Around the World
While natto is the most well-known answer to "what are fermented beans called," many cultures have their own unique versions. These fermented bean products vary significantly in taste, texture, and preparation method. Understanding these differences provides a richer appreciation for global fermented foods.
Douchi: The Versatile Chinese Fermented Black Bean
Douchi, also known as Chinese fermented black beans, is a staple ingredient in Cantonese cuisine. These are whole soybeans that have been fermented with salt and Aspergillus oryzae or Rhizopus mold. The resulting product is soft, salty, and intensely savory with a deep, complex umami flavor. Douchi is usually preserved in salt and is used as a seasoning rather than eaten on its own. It is a key ingredient in dishes like black bean sauce, steamed ribs, and stir-fried vegetables. Unlike natto, douchi has a firm texture and a salty, slightly spicy taste that lacks the slimy consistency.
Cheonggukjang: Korea's Quick-Fermented Bean Paste
Cheonggukjang is a Korean fermented soybean paste that shares similarities with natto. It is made by fermenting whole soybeans with Bacillus subtilis for a short period, typically two to three days. The result is a sticky, pungent paste that is used as a base for soups and stews. Cheonggukjang has a stronger aroma than natto and is known for its potent health benefits, including high levels of vitamin K2 and fibrinolytic enzymes. It is often described as a rustic, home-style ingredient in Korean cuisine.
Tempeh: The Firm and Nutty Indonesian Cake
Tempeh is a fermented soybean product from Indonesia that is fundamentally different from natto and douchi. Whole soybeans are cooked, dehulled, and inoculated with Rhizopus oligosporus mold, which binds the beans together into a firm, dense cake. The fermentation process is shorter than natto, typically lasting 24 to 36 hours. Tempeh has a nutty, earthy flavor and a firm, chewy texture that makes it highly versatile in cooking. It can be sliced, marinated, grilled, or fried. Unlike natto, tempeh is not sticky or slimy and has a pleasant, mushroom-like aroma.
Other Regional Fermented Beans
Beyond these three major types, other cultures have their own fermented bean specialties. Hawaijar is a fermented soybean product from Manipur, India, similar to natto but often spiced differently. Kinema, from Nepal and Bhutan, is another sticky fermented soybean product. In West Africa, iru and dawadawa are made from fermented locust beans and used as flavor enhancers. These examples demonstrate the global ingenuity in transforming simple legumes into flavorful, nutritious foods.
Health Benefits of Fermented Beans
Fermented beans offer a wide range of scientifically supported health benefits that extend far beyond basic nutrition. The fermentation process creates bioactive compounds that can positively impact digestion, cardiovascular health, bone density, and immune function.
Probiotics and Digestive Health
All fermented beans are rich in probiotics, live microorganisms that confer health benefits when consumed in adequate amounts. For natto and cheonggukjang, the primary probiotic is Bacillus subtilis, a spore-forming bacterium that can survive the harsh conditions of the stomach and reach the intestines alive. These probiotics help maintain a healthy balance of gut flora, support digestion, reduce inflammation, and may alleviate symptoms of irritable bowel syndrome (IBS). The fiber in fermented beans also acts as a prebiotic, feeding beneficial gut bacteria and promoting regular bowel movements.
Vitamin K2 and Bone Health
Natto is one of the richest dietary sources of vitamin K2, specifically the MK-7 form. Vitamin K2 plays a critical role in calcium metabolism by activating osteocalcin, a protein that binds calcium to the bone matrix. Adequate vitamin K2 intake is associated with increased bone mineral density and reduced risk of fractures, particularly in postmenopausal women. A single serving of natto can provide several times the daily recommended intake of vitamin K2, making it a powerful food for bone health.
Cardiovascular Benefits and Nattokinase
Nattokinase, the enzyme found exclusively in natto, has been extensively studied for its cardiovascular benefits. This enzyme has fibrinolytic activity, meaning it can break down fibrin, the protein involved in blood clot formation. Research suggests that nattokinase can help reduce blood pressure, prevent blood clots, and improve blood flow. Some studies indicate it may be as effective as certain medications for preventing deep vein thrombosis and stroke. However, individuals taking blood-thinning medications should consult their doctor before consuming large amounts of natto.
Iron Absorption and Anemia Prevention
Fermentation reduces the levels of phytic acid in soybeans, which normally inhibits iron absorption. This makes the iron in fermented beans more bioavailable than in unfermented soy products. Iron deficiency anemia is a common nutritional deficiency worldwide, and incorporating fermented beans into the diet can help improve iron status. Additionally, the vitamin C present in many fermented bean dishes further enhances iron absorption.
How to Eat Natto (and Other Fermented Beans)
For those new to fermented beans, especially natto, the unique texture and flavor can be intimidating. Fortunately, there are simple and delicious ways to prepare these foods that make them more approachable.
The Traditional Way to Eat Natto
The classic Japanese preparation for natto is called natto gohan. Start by placing a package of natto in a bowl and stirring it vigorously with chopsticks for about 30 to 60 seconds. This agitation aerates the beans and enhances the sticky texture. Add the included packets of Japanese mustard (karashi) and soy sauce (or tamari), then stir again. Serve immediately over a bowl of steamed short-grain rice. Top with finely chopped green onions (scallions), a sprinkle of dried bonito flakes (katsuobushi), and optionally, a raw egg yolk for extra richness.
Creative Ways to Incorporate Natto
Natto is surprisingly versatile and can be used in many dishes beyond rice. Add a spoonful to avocado toast for a protein and probiotic boost. Mix it into pasta dishes with olive oil and garlic for a umami-rich sauce. Use it as a filling for spring rolls or sushi. Natto can also be blended into salad dressings or dips to add creamy texture and savory flavor. For those who find the texture challenging, mashing the natto into a paste can help integrate it more smoothly into dishes.
Cooking with Douchi and Tempeh
Douchi is usually used as a seasoning. Rinse the fermented beans quickly if they are very salty, then mash them lightly before adding to stir-fries, braised dishes, or steamed dishes. They pair exceptionally well with garlic, ginger, and chili. Tempeh is best when cooked to develop a crispy exterior. Slice or cube it, marinate in soy sauce, garlic, and ginger, then pan-fry or bake until golden. Tempeh can be used as a meat substitute in sandwiches, tacos, stews, and curries.
Storing Fermented Beans
Proper storage is essential for maintaining the quality and probiotic content of fermented beans. Unopened natto can be refrigerated for several weeks or frozen for up to six months. Once opened, consume within a few days. Douchi, because of its high salt content, can be stored in an airtight container in a cool, dry place for months. Tempeh should be refrigerated and used within one week, or frozen for longer storage. Avoid freezing natto after it has been opened, as this can damage the bacterial cultures.
Where to Buy Fermented Beans
Finding fermented beans has become much easier in recent years due to increased interest in gut health and international cuisines. Most major supermarkets now stock some form of fermented bean product, but specialty stores offer a wider variety.
Asian Grocery Stores
Asian grocery stores are the best place to find a wide selection of natto, douchi, tempeh, and cheonggukjang. Natto is usually sold in small Styrofoam packages in the refrigerated or frozen section. Japanese markets often carry multiple brands, including varieties with different soybean sizes or added seasonings. Chinese markets stock douchi in bags or jars. Indonesian markets are the best source for fresh, high-quality tempeh.
Online Retailers
For those without access to Asian grocery stores, online retailers offer a convenient solution. Amazon, Japanese specialty food websites, and Korean grocery delivery services carry a range of fermented bean products. When buying online, check for cold-chain shipping for natto, as it requires refrigeration to maintain freshness. Tempeh can often be shipped at room temperature if it is freeze-dried or pasteurized, but fresh tempeh should also be shipped cold.
Health Food and Natural Grocery Stores
Many health food stores and natural grocery chains now carry tempeh and occasionally natto. Tempeh is often found in the refrigerated produce section, near tofu and other plant-based proteins. Some stores also carry freeze-dried natto powders or supplements, which can be a convenient alternative for those who want the health benefits without the texture. Always check the ingredient list to ensure the product is traditionally fermented and contains live cultures.
Making Your Own Natto at Home
For the adventurous home cook, making natto at home is a rewarding process that allows for complete control over the ingredients and fermentation conditions. Homemade natto can be fresher and more flavorful than store-bought versions.
Basic Equipment and Ingredients
To make natto at home, you need soybeans, natto starter culture (available online), clean glass or ceramic containers, a steamer or pressure cooker, and a method for maintaining a consistent temperature around 40°C (104°F) for 24 hours. A yogurt maker, an instant pot with a fermentation setting, or a warm oven with a pilot light can all work. Cleanliness is paramount to prevent unwanted mold growth.
Step-by-Step Process
- Wash and soak 500 grams of soybeans in water for 12 to 18 hours, changing the water once or twice. The beans should roughly double in size.
- Drain the beans and steam them in a pressure cooker for 30 to 45 minutes or until they are soft enough to be easily mashed between your fingers. Overcooking is better than undercooking.
- Spread the cooked beans in a thin layer on a clean tray and allow them to cool to approximately 40°C (104°F). Do not let them cool completely.
- Dissolve the natto starter powder in a small amount of clean water, then sprinkle it over the warm beans and mix thoroughly but gently to avoid mashing them.
- Transfer the inoculated beans to clean, shallow containers (glass baking dishes work well) and cover with a breathable cloth or perforated plastic wrap to maintain humidity while allowing air exchange.
- Place the containers in your fermentation chamber at a steady temperature of 40°C (104°F) for 24 hours. Check periodically; a white film or grayish coating is normal and indicates successful bacterial growth.
- After 24 hours, remove the natto, cover tightly, and refrigerate for 12 to 24 hours to allow the flavor to mature. The characteristic sticky texture will develop fully during this chilling period.
- Enjoy within one week, or freeze individual portions for up to six months.
Safety Precautions
While home fermentation is generally safe, there are important precautions. Use food-grade equipment and sterilized containers. If you notice any mold that is not the characteristic white or gray of Bacillus subtilis, particularly black, green, or pink mold, discard the batch immediately. Always trust your nose: if it smells putrid or unpleasant rather than nutty and savory, it is better to err on the side of caution and discard the batch.
Frequently Asked Questions About Fermented Beans
What does eating natto every day do?
Eating natto daily can provide significant amounts of protein, fiber, vitamin K2, and probiotics. Regular consumption may improve digestion, support cardiovascular health by helping to regulate blood pressure and prevent blood clots, and strengthen bones due to its high vitamin K2 content. Some people also report improved skin health and enhanced immune function. However, due to its high vitamin K2 content, individuals taking blood-thinning medications like warfarin should consult their doctor before adding natto to their daily diet.
What are Japanese fermented beans called?
The most common Japanese fermented beans are called natto. Natto is made from whole soybeans fermented with Bacillus subtilis. Other Japanese fermented bean products include miso (fermented soybean paste), soy sauce (shoyu), and tamari. However, when referring specifically to whole fermented beans, natto is the accurate term. There is also a regional variety called Hokkaido natto made with larger beans.
What is another name for fermented black beans?
Fermented black beans are most commonly known as douchi, which is the Chinese name. They are also referred to as Chinese fermented black beans, salted black beans, or simply black bean sauce when processed into a paste. In Cantonese cuisine, they are called dau si. They are not to be confused with regular black turtle beans, which are not fermented. The "black" refers to the color the soybeans turn during the fermentation and aging process.
What is the correct way to eat natto?
The traditional and most popular way is to eat it as natto gohan. First, stir the natto vigorously with chopsticks in its original container until it becomes sticky and stringy. Add the included soy sauce and mustard packets, then stir again. Serve immediately over steamed rice, and top with chopped green onions and optionally a raw egg yolk. Many people also add a dash of sesame oil or chili flakes. The key is to mix it well and eat it fresh for the best texture and probiotic content.
Are fermented beans good for you?
Yes, fermented beans are highly nutritious and beneficial for health. They are rich in protein, fiber, vitamins, and minerals, while the fermentation process enhances digestibility and creates bioactive compounds like vitamin K2 and nattokinase. The probiotics in fermented beans support gut health, and the anti-nutrient reduction improves mineral absorption. However, some fermented bean products, particularly douchi, are high in sodium, so they should be consumed in moderation as part of a balanced diet.
Can I make natto at home?
Yes, making natto at home is possible and relatively straightforward with the right equipment and starter culture. You need soybeans, natto starter (Bacillus subtilis spores), and a way to maintain a steady temperature of about 40°C (104°F) for 24 hours. A yogurt maker, instant pot, or warm oven works well. The process involves cooking the beans, inoculating them with the starter, and maintaining the temperature. Homemade natto can be fresher and more flavorful than commercial versions, but cleanliness is critical to prevent contamination.
Where can I buy natto?
Natto is widely available in Japanese and Korean grocery stores, often in the refrigerated or frozen section. Many large Asian supermarkets carry several brands. In the United States, it can also be found at specialty health food stores and some conventional grocery chains with international aisles. Online retailers like Amazon, Weee!, and Japan Centre offer a variety of natto products with delivery. Always check the expiration date and ensure the packaging is intact.
What does natto taste like?
Natto has a strong, complex flavor that is often described as nutty, savory, and deeply umami. It has a slight bitterness and a pungent, fermented aroma reminiscent of aged cheese or miso. The taste is not particularly sour or salty on its own. When mixed with soy sauce and mustard, the flavor becomes more balanced and approachable. The texture is the most challenging aspect for beginners, as it is slimy and sticky, with a sensation that coats the mouth.
Is it safe to eat fermented beans during pregnancy?
In general, fermented beans that are commercially produced and properly stored are safe to eat during pregnancy. They are a good source of protein and iron. However, natto and douchi should be consumed in moderation due to their high vitamin K2 content, which can theoretically interfere with fetal development if consumed in extremely large amounts. Pregnant women should also ensure that any homemade fermented foods are prepared with sterile equipment to avoid harmful bacteria. It is always best to consult a healthcare provider before making significant dietary changes during pregnancy.
How long do fermented beans last in the refrigerator?
Storage times vary by product. Natto typically lasts one to two weeks in the refrigerator after purchase, but it is best consumed within a few days for optimal flavor and texture. Unopened natto can be frozen for up to six months. Douchi, due to its high salt content, can last for months in an airtight container in the refrigerator. Tempeh usually lasts about one week in the refrigerator, though some brands may be shelf-stable until opened. Once opened, tempeh should be used within three to five days. Always check for signs of spoilage like off-odors, discoloration, or mold before consuming.
Key Takeaways
- The most direct answer to "What are fermented beans called?" is natto, a Japanese food made by fermenting soybeans with Bacillus subtilis.
- Fermented beans exist in many cultures, including douchi (Chinese), cheonggukjang (Korean), and tempeh (Indonesian), each with unique fermentation methods and flavors.
- Natto is an exceptional source of vitamin K2 (MK-7), which supports bone health and cardiovascular function, and contains nattokinase, an enzyme with blood-clot-dissolving properties.
- Fermented beans are rich in probiotics that support gut health, digestion, and immune function, with spore-forming Bacillus subtilis being particularly resilient.
- The fermentation process reduces anti-nutrients like phytic acid, making minerals such as iron and calcium more bioavailable.
- Tempeh is a firm, nutty cake that can be used as a versatile meat substitute, while douchi is a salty seasoning used in Chinese cooking.
- Natto has a distinct sticky texture and pungent flavor that many consider an acquired taste, but it can be made more approachable by mixing it with rice, soy sauce, and mustard.
- Homemade natto is achievable with basic equipment and starter culture, but requires careful temperature control and clean conditions.
- Individuals on blood-thinning medication should consult their doctor before consuming large amounts of natto due to its high vitamin K2 content.
- Fermented beans are widely available at Asian grocery stores, health food stores, and online retailers, making them accessible for most consumers.
Conclusion: Embracing the World of Fermented Beans
The answer to "What are fermented beans called?" opens the door to a diverse and nutritionally powerful category of foods. From the iconic sticky natto of Japan to the salty douchi of China and the firm tempeh of Indonesia, fermented beans offer unique flavors, textures, and health benefits that are hard to find elsewhere. Their rich probiotic content supports a healthy gut microbiome, while bioactive compounds like vitamin K2 and nattokinase provide targeted benefits for bones and the cardiovascular system.
Understanding the biological processes behind fermentation—how Bacillus subtilis transforms soybeans into natto, or how Rhizopus mold creates tempeh—helps you appreciate the craftsmanship behind these foods. This knowledge also highlights the importance of individual variability in how we digest and respond to these foods. Your unique microbiome composition can influence how well you tolerate and benefit from the probiotics in fermented beans. While common symptoms like bloating or gas may simply be temporary adjustments, they could also signal deeper imbalances in your gut flora.
The limitations of guessing your gut health are significant. Without objective data, it is impossible to know which bacterial strains you may be lacking or which foods might be most beneficial for your specific microbiome. This is where microbiome testing provides an educational and insight tool. By analyzing the composition of your gut bacteria, a test from InnerBuddies can reveal hidden differences in your microbiome that influence how you process foods like fermented beans. It can show whether you have adequate levels of Bacillus species, how your gut handles dietary fibers, and which specific probiotic strains might support your digestive health best.
For those curious about optimizing their gut health, understanding your personal microbiome can be a transformative step. A microbiome test provides personalized insights that help you make informed decisions about which fermented foods to include in your diet and how your body uniquely responds to them. Whether you are a seasoned enthusiast of natto or a curious beginner exploring douchi and tempeh, discovering your gut's specific needs can enhance your dietary choices and overall well-being.
Fermented beans represent a delicious, time-honored tradition of food preservation and health promotion. By incorporating them into your diet—and by gaining deeper insight into your own digestive ecosystem—you can unlock their full potential for your health. Start with small portions, experiment with different types and recipes, and observe how your body responds. The world of fermented beans is rich with opportunity for both culinary adventure and nutritional discovery.
Internal Links for Further Reading
- Explore our detailed microbiome testing service to understand your unique gut health.
- Read our comprehensive guide to fermented foods for more on how they affect the gut.
- Discover the benefits of probiotics and how they interact with your microbiome.
- Learn about Japanese cuisine basics for more traditional ways to enjoy natto.
Frequently Asked Questions
- What does eating natto every day do? Regular natto consumption supports bone health with vitamin K2, aids cardiovascular health through nattokinase, and provides probiotics for digestive balance. However, its high vitamin K content requires caution for those on blood thinners.
- What are Japanese fermented beans called? The primary term is natto, referring to whole soybeans fermented with Bacillus subtilis. Other Japanese fermented soy products include miso and soy sauce, which are processed differently.
- What is another name for fermented black beans? They are called douchi in Chinese, also known as Chinese fermented black beans or salted black beans. They are used as a salty, umami seasoning in many Asian dishes.
- What is the correct way to eat natto? Stir the natto vigorously until sticky, add the included soy sauce and mustard, mix well, and serve immediately over hot steamed rice. Top with green onions for added flavor.
- Are fermented beans good for you? Yes, they provide high-quality protein, probiotics, vitamin K2, and enhanced mineral absorption. They support digestive and cardiovascular health when consumed as part of a balanced diet.
- Can I make natto at home? Yes, with soybeans, a natto starter culture, and a consistent temperature of 40°C for 24 hours, you can make natto at home using a yogurt maker or instant pot.
- Where can I buy natto? Japanese and Korean grocery stores are the best sources. It is also available online through specialty retailers and some health food stores. Look for it in the refrigerated or frozen section.
- What does natto taste like? It has a nutty, savory, and intensely umami flavor with a slight bitterness and pungent aroma. The texture is slimy and sticky, which is an acquired characteristic.
- Is it safe to eat fermented beans during pregnancy? Generally yes, in moderation. They offer protein and iron. However, consult your healthcare provider before making dietary changes, particularly due to the high vitamin K2 content.
- How long do fermented beans last in the refrigerator? Natto lasts 1-2 weeks, douchi can last months, and tempeh about one week. Always check for off-odors, mold, or discoloration before consuming.
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