How to Make Shio-Koji

When you buy rice koji, it will look like rice with a powdery white substance on it. This is because the rice has been inoculated by the spores of a fungus called Aspergillus oryzae, also known as “koji.”  Koji is the key to making fermented foods such as miso paste, mirin, sake and soy sauce.

Today, I’m using rice koji to make a seasoning called shio-koji, but in a previous post I used rice koji to ferment sweet rice to make amazake.

When rice koji is mixed with water and salt, the koji is activated and fermentation of the rice begins. The carbs and proteins in the rice turn into sugars and amino acids. One of the amino acids is glutamate which adds umami or a deep flavor. You will be pleasantly surprised by the sweet and salty flavor of shio-koji. It adds flavor to food and is healthy too.

Basic Shio-Koji Recipe 

Rice koji 200 grams

Salt 60 grams

Water 300 ml (1 1/3 cups)

1. Mix together rice koji and salt, rubbing the grains of rice between your fingers.

2. Heat the water to 60-70 C (120-140 F). Add it to the rice and salt mixture and stir.

3. Put the mixture in a clean container with the lid loosened or with a paper towel covering the top.

4. Stir it once a day with a clean spoon.

In the summer it takes 7 days to make shio-koji; in winter it takes 14 days. Taste it around 5 days to make sure the fermentation is taking place. It should not have a “rotten” or off flavor. The taste will be pleasantly sweet and salty. When the shio-koji is done, the color will be light brown.

Here is the finished shio-koji. Keep covered in the refrigerator and use in place of salt of soy sauce. It can be used to marinate fish or meat, to make dressings, pickle vegetables and much much more.