Started a batch of natto this evening. 600g of dry soybeans soaked about 8 hours, then pressure cooked for 20 minutes. Mixed in some spores, put a thin layer of the beans in these glass containers, then covered with a damp cloth and lids. I'll keep these in my makeshift incubator (a cooler with a reptile cage heating mat) overnight at 40C, then put them in the fridge in the morning, and enjoy them the day after.
How did it turn out?
I should get someone to help stir it up for better photos, as the strands disappear too quickly for me to do everything, but it was delicious! My wife and kids all enjoy eating it (unlike some of my other ferments), and it is a fast ferment with stable results, so a winner in our house.
That looks really interesting! I make lots of tempeh at home, but I've never heard about "natto" before. From reading the wiki I can see that the microorganism is a specific variant of Bacillus subtilis bacteria. Where did you get your spores from?
I'm in Taiwan, and we have reasonable local access to various spores from Japan (especially for Koji and natto) through a few online retailers.
My natto comes out much like yours, a bit thin on the strings but tasty. I can’t get dry soy beans where I am so use chick peas or black eye beans. 