Using adzuki, black, kidney, or lentils requires cooking the beans, cooling them, and inoculating them with a suitable natto culture. You can succeed, but your result likely tastes milder, feels softer, and forms fewer sticky strands than traditional soybean natto.
This practical guide walks home fermenters through adapting natto-making methods for adzuki, kidney, black beans, and lentils, with advice on preparation, inoculation, safety, flavor, and texture.
Traditional Natto Starts With Soybeans
Japanese natto begins with cooked soybeans inoculated with Bacillus subtilis, a bacterium associated with Bacillus natto. During fermentation, the beans develop the savory aroma, strong flavor, and sticky coating that distinguish traditional natto.
Those traits give you a useful baseline. An alternative legume rarely duplicates the aroma, strands, and tender-but-firm texture of soybean natto at the same time.
- Sticky strands: Soybeans often hold together in slippery threads as microbial compounds develop during fermentation.
- Pungent aroma: Traditional natto has a sharper smell than many seasoned lentil and bean fermentations.
- Soft interior: Cooked soybeans become tender without dissolving into a purée-like mass.
- Bean structure: Whole seeds remain visible after the sticky coating forms.
A natto-style dish can also use another legume, cooked grain, or blended bean. Your version depends on controlled fermentation and seasoning rather than a perfect match with every feature of Japanese natto.
Because soybean natto begins with soybeans, alternative legumes require adjusted preparation rather than a copied fermentation routine.
Adzuki, Kidney, Black Beans, and Lentils Suit Home Fermentation
Adzuki beans offer a practical starting point because their starch-rich skins soften into a creamy mixture during cooking and fermentation. Kidney beans, black beans, red lentils, and chickpeas also work, although their size and density change their water and heat requirements.
| Legume | Likely result | Main preparation concern |
|---|---|---|
| Adzuki beans | Creamy, mild, gently sweet | Short cooking and careful stirring |
| Black beans | Dark color, earthy taste | Firm skins and strong cooked-bean flavor |
| Kidney beans | Soft texture, mild savoriness | Long cooking and possible splitting |
| Red lentils | Tender, mild, less stringy | Quick breakdown into a soft mass |
| Chickpeas | Firm bite, nutty aroma | Dense texture and slower softening |
Adzuki beans and red lentils can produce a smooth, spoonable preparation. Kidney beans and chickpeas usually retain more of their cooked bite, while black beans add a dark color and earthy flavor.
Your choice depends on the texture and taste you want. Choose adzuki beans for creaminess, chickpeas for structure, or black beans for a bolder, darker result.
You also need to account for how each bean breaks down under heat. Red lentils collapse sooner than chickpeas, and a batch that dissolves during simmering may also become too soft during fermentation.
A Controlled Culture Gives Better Consistency
A commercial culture offers a more controlled route than exposure to kitchen air. Traditional natto spores, a packaged Bacillus subtilis culture, or another culture listed for the chosen legume lowers the chance that mold or unrelated bacteria will dominate.
Rice koji is not interchangeable with a legume-compatible natto starter. Its mold and yeast do not reproduce the sticky strands formed by suitable Bacillus subtilis strains.
You need a starter to repeat batches with reasonable consistency. Follow its directions for moisture, temperature, and inoculation because beans hold different amounts of water than soybeans.
Matching Preparation to the Bean
The size difference behind the earlier texture contrast also affects soaking and cooking. Sorting removes stones and damaged seeds, while rinsing removes dirt that could disturb the ferment.
Larger legumes need longer soaking and cooking than small lentils. Red lentils absorb water quickly and may split during an open simmer, so you need restraint rather than a soybean timetable.
- Sort the dry beans: Remove damaged seeds and debris, then rinse the legumes in cool water until the water runs clearer.
- Soak according to size: Follow package directions or a food-safety source for the specific legume rather than applying a soybean schedule.
- Cook with restraint: Add enough water to prevent scorching, and simmer until the beans yield to gentle pressure.
- Cool before inoculation: Keep the culture away from steaming-hot beans because excessive heat can damage it.
- Drain excess liquid: Leave the beans moist without allowing a watery ferment that favors unwanted growth.
- Season after fermentation: Add salt and other flavorings once the culture has developed, following the starter directions.
Red lentils need less cooking than black beans because they break down faster. Chickpeas and kidney beans can stay firm through soaking but need enough cooking to become tender enough for fermentation.
Your cooked beans also absorb different amounts of water. Adzuki beans may become creamy, while chickpeas retain firmer surfaces that need even moisture for the culture.
Never rinse cooked beans after inoculation. The remaining cooking liquid can distribute spores across the seeds and within the sticky bean texture.
Fermenting Alternative Beans Safely
The cooling step protects your culture, but temperature control during fermentation protects the entire batch. Excess heat can kill the culture, while inadequate heat can leave the mixture vulnerable to mold.
Use the exact temperature range published for your starter. Kitchen air and an unmeasured countertop setting do not replace that range.
Mix cooled beans with the inoculant at the supplier’s stated ratio. Spread the mixture in a clean container with the air exchange specified for fermentation, away from direct sunlight and kitchen splashes.
Alternative legumes do not necessarily ferment at the same rate as soybeans. Red lentils can turn creamy during a short fermentation, while chickpeas and kidney beans may retain more bite.
You may notice clean acidity and a sticky coating before the entire batch reaches your target texture. Your nose and eyes still need to stay involved throughout that period.
Discard the batch after fuzzy growth, unexpected blue, green, pink, or black coloration, or a rotten odor. Strong ammonia alone is familiar in natto, but sour, rotten, or solvent-like odors do not belong in a sound ferment.
Refrigerate the beans promptly after the culture reaches its target aroma and texture. Follow the culture’s refrigeration and use-by directions, and seal the container to limit moisture loss and exposure to nearby foods.
Your equipment also affects contamination risk. Clean containers, utensils, and work surfaces before inoculation, and avoid splashing fermented liquid across unrelated foods.
Flavor and Texture Change With Every Legume
The bean usually affects the finished dish more than the seasoning. An adzuki ferment can taste creamy and mildly sweet, while a black-bean version has a darker color, firmer skins, and a deeper earthy note.
| Legume profile | Texture | Flavor direction |
|---|---|---|
| Soft and creamy | Adzuki beans | Mild, sweet, gentle |
| Soft and bean-centered | Kidney beans | Cooked-bean savoriness |
| Firm and earthy | Black beans | Deep, vegetable-like notes |
| Pasty and tender | Red lentils | Soft, creamy, mild |
| Substantial and nutty | Chickpeas | Dense, roasted-bean character |
Salt sharpens acidity, scallions add freshness, sesame contributes richness, and grated daikon cuts through strong flavors. Soy sauce and miso deepen the fermented taste, but both contain soy.
A soy-free bean ferment does not guarantee a soy-free meal. Check miso, soy sauce, broth, sauces, and shared processing equipment, particularly for a person with a soy allergy.
Fermented beans may also conflict with medical restrictions involving histamine, sodium, or specific organisms. Your clinician can assess those concerns because fermentation does not suit every person or diet.
After weighing those health constraints, choose a legume and formula that suit your kitchen experience and available equipment.
Hold salt until you taste the plain ferment. Adding it before inoculation can encourage unwanted growth and complicate your judgment of the bean flavor.
Choosing the Most Practical First Batch
A small test lets you judge aroma, texture, flavor, and storage before making a larger quantity. Use one small bean portion, a fresh commercial inoculant, and clean containers prepared according to the culture directions.
Set a Clear Goal
Choose adzuki beans or red lentils for a creamy, mild experiment. Choose black beans for a darker, earthier profile, or select chickpeas and kidney beans for a substantial bite.
For natto using lentils, red lentils give the softest outcome, while green and brown lentils usually retain more skin and structure. Your choice affects spoonability and the number of sticky strands.
You can use the best beans for making natto by matching the legume to your preferred result. Creaminess calls for adzuki beans, pronounced structure calls for chickpeas, and a dark profile calls for black beans.
Evaluate Before Scaling
- Track the timing: Record when inoculation begins, when acidity first appears, and when the target texture emerges.
- Inspect every layer: Check the surface and center because uneven air or moisture affects different areas.
- Taste before seasoning: Compare bean flavor, acidity, aroma, stickiness, and harsh or rotten notes.
- Check storage: Confirm that texture, smell, and appearance remain acceptable through the recommended refrigeration period.
- Change one variable: Alter bean type, cooking level, or fermentation time separately so your notes identify the cause.
Probiotic claims deserve caution because probiotic fermentation does not guarantee identical live cultures or nutrient levels. Alternative-bean natto should not be compared with a verified traditional product without evidence.
Your first batch also lacks the advantage of a known soybean formula. A small sample gives you room to adjust bean hydration, cooking level, or container depth before a larger batch depends on the same variables.
Putting the Fermentation Method Together
To begin, select one legume and sort the dry seeds. Soak and cook it according to its own directions, then cool the beans to the temperature required by your natto starter.
After inoculation, maintain the supplier’s temperature range and container conditions. Check the beans during the stated fermentation window for acidity, aroma, coating, texture, and discoloration.
Once the batch meets its target profile, refrigerate it promptly and follow the culture’s storage directions. Your next batch can change one variable, such as bean type or cooking level, so your notes show which step shaped the result.
Yes, because adzuki beans, black beans, kidney beans, lentils, and chickpeas can all undergo controlled fermentation, though their texture and flavor will differ from traditional natto.
The basic process for how to ferment other beans into natto closely resembles soybean preparation, but bean hydration and starch content require legume-specific timing. Your starter’s directions remain more reliable than a fixed schedule drawn from soybean natto.
Key Takeaways
- Choose by texture: Adzuki beans and red lentils soften quickly, while chickpeas, kidney beans, and black beans retain more structure.
- Use a compatible culture: Traditional natto spores or a suitable Bacillus subtilis culture offers control that kitchen air cannot provide.
- Prepare for bean differences: Larger beans need longer cooking, and red lentils need less heat than chickpeas or black beans.
- Follow culture directions: Use the stated inoculation rate, temperature, fermentation window, and refrigeration period for your starter.
- Start with one legume: A small batch lets you compare aroma, acidity, coating, texture, and storage before scaling.
- Avoid substitute claims: A natto substitute for soybeans can be satisfying without matching traditional natto’s strands, aroma, or live-culture profile.
FAQ
Can you make natto using beans other than soybeans?
You can make natto-style food with adzuki beans, black beans, kidney beans, lentils, or chickpeas. Cook the beans, cool them, inoculate them with a suitable culture, and follow the supplier’s fermentation directions. Expect a different flavor and texture rather than an exact soybean version.
Which beans work best as substitutes for soybeans?
Adzuki beans produce a creamy, mild result, while black beans offer darker color and an earthier taste. Chickpeas and kidney beans provide more structure. Your preferred outcome matters more than a universal ranking, so begin with a small batch of one legume.
Can lentils, chickpeas, or black beans be used to make natto?
A simple fermentation can turn lentils, chickpeas, and black beans into natto-style dishes. Red lentils become creamier and milder, chickpeas retain bite and a nutty flavor, and black beans bring a dark, earthy profile.
Do you need natto spores to ferment alternative beans?
You need a controlled culture for more consistent results with an unfamiliar legume. Traditional natto spores or a suitable Bacillus subtilis culture can inoculate cooked beans. Rice koji and uncontrolled kitchen air are unsuitable substitutes without specific instructions.
How does texture and flavor change with other beans?
Your bean choice changes both traits. Adzuki beans tend toward creaminess and mild sweetness, red lentils become soft and mild, chickpeas stay substantial, and black beans offer firm skins with earthy notes.
What is the basic process for making natto at home?
Sort, rinse, soak, and cook your chosen beans. Cool them, mix in a compatible inoculant, and ferment at the stated temperature. Refrigerate the finished beans once they reach the expected aroma and texture.
