I’ve been making my own natto, which is a type of Japanese fermented soybean. I’ve heard about its health benefits and have been making it since last year. Singapore sells it, yes, but they’re in tiny styrofoam packs that are bad for the environment. I learnt it from NattoKing, which was a website dedicated to this food. Unfortunately, the NattoKing website is no longer up.
I found other guides such as this one from Happy Donabe Life. Unfortunately many of these make the process seem complicated and as if you need a lot of special equipment. Here’s my lazy version. I don’t sterilise my stuff and didn’t buy any special equipment; everything is from the house (except for my starter natto + soybeans).
To make natto, you just need something to cook the soybeans. After that, fermentation is just heat and insulation and starter culture (the natto bacteria). As long as you have those three, the specifics don’t actually matter that much.
1. Pressure Cooker (some rice cookers are pressure cookers too)
3. Insulation. I used cooler bags and jackets.
4. Heat. For me, that was glass jars/something to hold hot water
5. Large container to hold the insulation
6. Some natto (the sushi bars in supermarkets usually sell them. Liang Court does, too.)
1. Soak the soybeans overnight.
2. Drain and put soybeans into a bowl (ceramic/metal).
3. Cook it in the pressure cooker with the bowl. I fill the cooker with some water (make sure the water level is below the bowl). When the pressure cooker starts releasing steam kinda like a steam train, I let it steam for 15 ish minutes more before turning off the stove. I know that it’ll still be cooking as the pressure decreases.
4. As it depressurises, I prep my cooler bags to make a chamber for the beans to ferment in. I just put the smaller bags into the bigger ones (around 3 bags). I also layer a thick jacket in the large container, like a nest for the chamber.
5. Open up the cooker. Take the natto and mix it into the bowl with a spoon. I usually use one whole box if it’s store bought. For subsequent batches, I used the previous natto. Sometimes I replenish with new store bought natto (when the natto stops becoming very sticky).
6. Stuff the bowl into the fermentation chamber. Cover with jacket.
7. Fill the glass jars/other container with all the hot water from the pressure cooker. This will keep the temperature high enough. Don’t close the cap too tight, or you’ll have problems unscrewing it after it cools down. I put this in between the natto and one layer of cooler bags. Then I spam (aka use a lot of) jackets until it’s all wrapped snugly.
8. Let it ferment overnight (around 12-14 hours). Some like to ferment it for 24 hours or more.
9. Voila! Store in the fridge and eat it as you wish.
Super lazy edition
I haven’t tried this, but I just realised my pressurised rice cooker has a “keep warm” feature and it has kept soups warm for overnight periods before. So in actual fact, I could just:
1. Cook the soybeans in the rice cooker
2. Mix in the natto
3. Press the “keep warm” option
4. Eat it the next morning.
Simple! Not sure if “keep warm” will truly be warm enough (roughly 40 degrees Celsius) for the natto to ferment, but I think it’ll work nicely.