Kome Koji: Fermenting rice with Aspergillus Oryzae
Now let’s get a little funky and talk a little koji shall we?
This time around instead of just using rice for my beer, I decided to use rice koji which is essentially rice with a type of fungus called koji or Aspergillus oryzae growing on it.
Now some may think “Woah now Shun, you’re gonna put some moldy looking rice into the beer you’re going to sell?” Yes, and don’t worry it’s totally edible.
Koji is a type of fungus that is native to Japan and is used in many of the staple ingredients used in Japanese cooking. Miso, Sake, Soy Sauce, Mirin are among the few things that use koji in its production process.
What the koji does is quite simple, and they just break down large things transforms them into smaller bits and pieces. In case with rice, the koji can break down the starch in the rice into sugars and other components that are the building blocks to the flavor of umami.
So why put it in beer?
To put it simply, I wanted more rice flavor in the beer that I am going to make this time around.
The problem with adding more rice to increase the flavor of rice in beer what happens is that the beer starts to lose body and becomes very light. Instead of having something with a little depth and mouth feel, you start getting closer to water. So just adding ingredients to beer doesn’t make it always better or flavorful. So to over come that problem we decided to use rice koji instead of just rice. By fermenting rice together with the koji, you can extract more of the natural sweetness and the fragrance of rice. So you get more of that rice flavor and fragrance without having to put as much rice in the beer which solves the whole “not enough body problem”.
making rice koji
Making rice koji is actually quite easy, and only takes two simple ingredients: rice and koji.
Here are the steps :
Measure out 600 grams of rice
Soak the rice in water for 5-7 hours until the rice turns completely white
Leave the rice out in a strainer for a couple of hours to get rid of the excess moisture
Wrap the rice in a steaming cloth and steam the rice for 40 and check if you can squish the rice grain between your fingers
Let the rice cool to about 40 degrees Celsius and speed the rice out onto a tray getting rid of any clumps with your hands
Once the rice is nice and spread out and at 40 degrees Celsius, spread the koji powder over the rice evenly using a sieve
Using your hands rub the koji powder into the rice without squishing the rice too much
Once fully mixed, wrap the koji and rice mixture up tightly in a breathable cloth
Place the cloth with the rice and koji in a container over two water bottles with water that is about 70 degrees Celsius
Close the container with its contents and leave it be for 24 hours. Make sure to keep the inside of the container from 28-40 degrees Celsius
After 24hours, unwrap the rice and place it on a board to mix the contents together once more to get all the moisture and temperature evenly throughout
Wrap the rice up again this time a little less tightly and place it back in the container to ferment keeping the temperature now from 35-42 degrees Celsius and leave for another 36 hours
Your Rice Koji should be all done!
Some points to watch out for:
Make sure that the rice and koji mixture does not fall under 20 degrees or go over 43 degrees Celsius.
If the rice seems to be drying out, wet a cloth a place over the wrapped rice
The rice should start smelling a little like sake and taste sweet, almost like chestnuts
