My explorations in miso making can be found here and here. Now I’m going to describe the basic steps involved. If you decide to make your own and order the koji spores from GEM Cultures (which is where I get mine) you’ll receive detailed ingredient lists and measurements and instructions. Also Sandor Katz has a chapter all about miso making and koji rice culturing in his new book for those interested in learning more.
But maybe you just want to know what is involved in the process before you decide if you want to make your own? That is what I’ll be describing.
First, miso comes in many varieties. Those of you who buy miso are already familiar with this. There are several kinds. I’ll just be talking about red miso for simplicity sake. Red miso is fermented the longest, minimum 6 months to a year but sometimes left to incubate for multiple years. It also uses the most salt and a much higher ratio of soybeans to koji rice compared to other misos. This slows down the fermentation process which is why it’s left to incubate longer than the other types.
Making miso involves two separate culturing processes:
1) Inoculating rice or barley (or wheat if you’re making shoyu/soy sauce) with koji spores (the spores of the mold responsible for making miso, sake, and soy sauce as well as amazake). Yes, you will be intentionally growing mold on your rice. But a special kind of mold.
2) Combining this cultured koji grain with cooked soybeans (or your choice of legume), salt, water, and a few Tbs of unpasturized miso and then packing this into a crock and storing it for a while. This is the easy part.
You can buy already cultured koji rice, but it’s significantly more expensive than purchasing the koji spores and inoculating your own rice and you can only get sweet rice koji. I recommend making your own koji rice. It’s a bit time consuming but not too difficult and you’ll end up with a lot more koji rice to play around with. But if this part of the process is deterring you, then just buy some koji rice and make some sweet miso or try using a red miso recipe with your sweet rice koji and see what happens.
Making Koji Rice
First you steam the rice then cool it down until it is warm. You mix the koji spores with some flour that you’ve heated and then mix that in with your rice. Then you wrap the whole thing up in a big bundle of towels to keep it warm and put it in a warm place. I use a large picnic cooler with mason jars of hot water and a hot water bottle packed in around the towel bundle. You unwrap it and check it every two hours throughout the day to make sure it’s staying the right temperature and then repack it into the cooler. You check it one last time before bed and then first thing in the morning.
At this point it should start smelling kinda mushroomy/yeasty (Audrey and I think it smells wonderful; Aaron says it smells ‘interesting’) and it should be dusted with a white growth. You take it out of the bundle and spread it into trays (I use pyrex baking pans) in a thin layer. Because the koji is now metabolizing quickly, it’s creating a lot of heat so that’s why we spread it out: to keep it from getting too hot in the center and killing itself. Again you’ll wrap up these trays and put them back in the cooler with warm water bottles (I make the water much less hot at this point). And again you’ll unwrap them every two hours and take their temperature and stir them up a bit if they’re getting too warm. Then rewrap them and put them back to incubate. Check one last time before bed then first thing in the morning.
If you’ve done everything right enough and it hasn’t gotten too cold or too hot and died off then you should find that your rice is completely covered with a fuzzy white growth possibly spotted with a bit of green or yellow and if you break open a rice grain it’ll be the same opaque white at least half-way through to the center. Sorry for the horrible picture of this part. But hopefully you can see the clumps of rice covered with the koji.
You’re done making koji rice! You can now make miso or store it for a few days in the fridge, a few months if you dehydrate it or freeze it.
When you’ve recovered from making koji rice and have decided to move on to making miso, you’ll soak your soybeans overnight. Cook them until soft. Mash them. Mix them with salt and some of the cooking water and a few Tbs unpasturized miso (to seed it with beneficial bacterial; miso is made by the koji and a complex combination of beneficial bacteria and yeasts).
Finally you’ll mix in your koji rice and pack the whole thing into a large crock. I like to sprinkle salt on the very top. Cover this with a plate or other lid (like you would when making saurkraut) and weigh it down with a large gallon jug of water. Cover the whole thing with a towel and tape around it so the towel will keep any bugs out. Label and put in a cool location. I use our dirt lined cellar under the house. Forget about it for at least six months or leave it for a few years. Or make two crocks and open one earlier than the other (my new approach).
I know this probably all sounds super involved. But it’s not that bad, really. It mainly requires a couple ‘hang around the house days’. Choose a rainy winter weekend and make some soup while you babysit your koji. Oh, and set a timer to let you know when two hours has passed, that really helps. And if you know that you already enjoy fermenting things (or you’re a kitchen scientist kind of person) then you’ll probably love this. It’s fun. Especially when you open the finished crock!