How to Make Natto

This recipe introduce 2 simple methods of how to make natto at home.

By following these methods, you can create your own delicious and nutritious batch of natto using a dash of powder starter or some leftover store-bought natto.

What’s Natto?

Natto is a traditional Japanese food made from fermented soybeans. The soybeans are steamed or boiled, and then a bacteria called Bacillus subtilis is added to the mixture to ferment the beans. The resulting product has a sticky, slimy texture and a strong flavor.

Natto is a popular breakfast food in Japan and is often eaten with rice and other toppings like mustard, soy sauce, and chopped scallions. You can also serve natto as a healthy side dish.

Natto is rich in protein, vitamins, and minerals and is considered a healthy food by many people. However, natto has a distinctive and somewhat strong odor that can be described as pungent, earthy, and slightly cheesy. The smell is kinda similar to ammonia or old socks. It may take some time for some people to appreciate its unique flavor and texture.

Benefits and side effects

Natto has several potential health benefits, including:

1. High Nutritional Value: Natto is rich in protein, fiber, vitamins (especially vitamin K2), and minerals such as iron, calcium, and magnesium.
2. Probiotics: Natto contains beneficial bacteria that can help promote a healthy gut microbiome and boost the immune system.
3. Heart Health: Natto contains an enzyme called nattokinase, which may help improve blood flow and lower the risk of heart disease.
4. Bone Health: Natto is a good source of vitamin K2, which is important for bone health and may help reduce the risk of osteoporosis.
5. Anti-Inflammatory: Natto contains compounds that have anti-inflammatory properties and may help reduce inflammation in the body.

However, people who are allergic to soy should avoid eating it.

Additionally, natto contains high levels of vitamin K, which can interfere with blood-thinning medications such as warfarin. Therefore, people taking these medications should consult with their healthcare provider before consuming it.

Lastly, some people may experience digestive discomfort or bloating when consuming natto, which may be due to its high fiber content or the presence of certain bacteria.

How to make natto with natto starter?

Natto starter is a type of bacterial culture used to ferment soybeans and produce natto. You can easily find different brands of starters sold in small packets on Amazon or at many Asian grocery stores.

To make natto with starter, start by soaking soybeans overnight, steaming them, and then draining them thoroughly. Dissolve the powder starter in cold water, mix it with the cooked soybeans, and then ferment the mixture in a warm oven for 24 hours.

How to make natto with packaged natto?

We can use packaged natto to make new batches of natto because it contains live cultures of bacteria that are responsible for the fermentation process.

When you mix the packaged natto with cooked soybeans, the live bacteria will multiply and ferment the soybeans, resulting in a new batch of natto.

This method of using packaged natto as a starter is a convenient way to make natto at home without having to purchase a separate starter.

How to Make Natto Q&A

1. Do I have to steam the soybeans? Can I boil them instead?

Traditionally, steamed soybeans are better than boiled soybeans for making natto.

This is because steaming the soybeans can help to preserve their natural enzymes, which are essential for the fermentation process. Boiling the soybeans, on the other hand, can destroy some of these enzymes, which may result in a less consistent fermentation process or even failure.

Additionally, steamed soybeans tend to have a firmer texture and retain their shape better during fermentation, while boiled soybeans may become mushy or break apart.

Although it’s highly recommended to steam your soybeans for making natto, many people have successfully made natto by boiling soybeans for 2 to 3 hours until mushy. You can give it a try, and just make sure to cool the boiled soybeans before adding the starter to avoid killing the bacteria.

2. What if I don’t have a steamer?

Most instant pots actually come with a steaming rack or steaming basket. You can easily use your instant pot to steam the soybeans.

If you don’t have a steamer or instant pot at home, you can use a large pot to steam the soybeans by filling it with 2 inches of water and placing a steamer rack (or three golf-ball-size aluminum foil balls) at the bottom. Next, put the soybeans in a plate on top of the rack/balls, cover the pot with a lid, and bring the water to a boil. Remember to check and add water as needed to prevent the pot from boiling dry.

3. How to prevent mold during fermentation?

To ensure successful fermentation of the soybeans, it is important to use clean and sterilized containers and utensils during the preparation process.

You can either bake all the equipment you plan to use at 250°F (121°C) for 30 minutes, or boil them in a large pot of water for at least 5 minutes. This will help to eliminate any potential bacteria or contaminants that could interfere with the fermentation process.

4. What’s initial and secondary fermentation?

Natto’s initial fermentation occurs when the starter is mixed with cooked soybeans and left to ferment for around 24 hours at a warm temperature, typically between 100-110°F (37-43°C). During this time, the bacteria in the starter culture ferment the soybeans, resulting in the characteristic sticky texture and unique flavor.

After the first fermentation is complete, we need to transfer the soybeans to a refrigerator for an additional 12 hours. This secondary fermentation can increase the amino acids and flavor and reduce the ammonia odor. You will find that the natto turns less stinky and more slimy after the secondary fermentation in the fridge.

5. Why puncture holes on the plastic food wrap?

We cover soybeans with two layers of plastic food wrap to create an environment that is conducive for the growth of the natto bacteria.

The plastic wrap helps to maintain a high humidity level inside the container, which is important for the growth and multiplication of the bacteria. Additionally, the plastic wrap creates a barrier that helps to prevent contamination from other bacteria and mold spores that may be present in the air.

Natto bacteria require oxygen to survive and reproduce. By puncturing small holes on the plastic wrap, the air can flow in and out of the container, ensuring that the bacteria have access to the oxygen they need for the fermentation process.

6. Does natto made using powder starter and packaged natto taste different?

No, based on my personal experience, there is no difference in taste or texture between them. You can choose either of these two methods, based on which one is more convenient for you.

7. How to enjoy natto

Natto itself tastes earthy and bland. It may have an unpleasant odor to those who have not tried it before. Therefore, you will need to season the natto before enjoying it.

• Soy Sauce: Adding a few drops of soy sauce to natto is a simple and classic way to add flavor. The saltiness of the soy sauce can help to balance out the strong earthy flavor. I also like to add a dash of sugar to balance the saltiness of the soy sauce.
• Mustard: Packaged natto always comes with a small pocket of Japanese mustard. Mixing a small amount of mustard can help to give it a spicy kick.
• Scallions: Chopped scallions can add a fresh, savory flavor. They also provide a nice crunch.
• Sesame Oil: Drizzling a small amount of sesame oil over natto can add a nutty, rich flavor.
• Mentaiko: Mentaiko is a type of spicy cod roe that is often served with natto. Mixing a small amount of mentaiko can add a burst of umami flavor and heat.
• Raw Egg: In Japan, natto is commonly served with hot steamed rice and raw egg yolk. However, it is important to note that consuming raw eggs is not recommended in other countries due to the potential risk of foodborne illness.

EQUIPMENT You Will Need:

• Steamer (If you don’t have a steamer, you can steam using a regular pot or an instant pot.)
• Oven with proof mode (Can also use a yogurt maker or an instant pot with a “yogurt” mode, or a rice cooker with a “keep warm” function.)
• Food storage containers (Use glass or ceramic ones)
• Plastic Food Wrap
• Refrigerator

INGREDIENTS List:

Natto starter method – will produce 900g natto (100g per serving)

• 2 cups soybeans
• ½ tsp natto starter
• 2 tbsps cold water (Use sterile water, such as bottled water, boiled and naturally cooled water.)

Store bought natto method – will produce 900g natto (100g per serving)

• 2 cups soybeans
• 2 tbsps store bought natto

Step-by-step INSTRUCTIONS:

1. Wash the soybeans in cold water by gently rub the beans with your hands. Be careful not to rub too hard or the soy skin may break. Wash for a couple of times until the water turns clear.

2. Soak the washed soybeans in 6 cups of cold water overnight for around 10 hours. Drain the water.

3. Transfer the soybeans to a steamer, steam the soybeans for about 2½ hours until they are soft and can be easily mashed with fingers.

4. As you are steaming the soybeans, wash container you are going to use later thoroughly with soap and water. Place the them on a clean baking sheet, bake at 250°F (121°C) for at least 30 minutes to ensure that the containers and utensils reach a temperature of at least 165°F (74°C), which is the minimum temperature to kill most bacteria.

5. Transfer the steamed soybeans to a sanitized container and let the soybeans cool to room temperature.

6. – natto starter method: Add ½ tsp of natto starter spores powder and 2 tbsps of cold water (use bottled water or boiled then cooled water) to a small bowl, stir until the powder is fully dissolved. Pour the starter water onto the steamed and cooled soybeans (about 900g) and mix thoroughly with a clean spatula.

7. – store bought natto method: Add 2 tbsps of store-bought natto to the steamed and cooled soybeans (about 900g) and mix thoroughly with a clean spatula.

8. Cover the soybeans’ container loosely with plastic food wrap, then puncture the wrap with a toothpick every ½ inch. Next, press down the food wrap gently to ensure it conforms tightly to the surface of the soybeans.

9. Cover the the soybeans’ container tightly with a second piece of plastic food wrap, then puncture the wrap with a toothpick every ½ inch.

10. To ferment soybeans, first, place a steam rack and add 2 inches of water to an instant pot, yogurt maker, or rice cooker. Then, put the soybean container on the steam rack, making sure the container is not submerged in water. Close the lid and activate the “yogurt” mode or “keep warm” mode in the appliance and let it ferment for 24 hours. Alternatively, you can use an oven with the “proof” mode to ferment the soybeans without requiring a water bath. In this case, simply place the container in the oven and let it ferment for 24 hours.

11. 24 hours later, put the containers on the countertop and let them cool down to room temperature. Then keep them in the fridge for at least 12 hours before enjoy. This secondary fermentation can increase the amino acids and flavor and reduce the ammonia odor.

13. To store your homemade natto, you can keep it in an airtight container in the refrigerator for up to one week. Or you can pack them in small individual containers and store them in the freezer for up to one month. Thaw it in the refrigerator overnight before consuming.

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