Rice Koji Recipe
Rice Koji is a traditional Japanese ferment made from cooked rice inoculated with Aspergillus oryzae spores. Once created, it becomes a powerhouse of enzymes used to create deep, complex umami flavours by breaking down starches and proteins of regular ingredients into flavorful sugars and amino acids. The application range for Koji is extremely wide, from marinating and tenderizing meat to use as a salad dressing component. Koji essentially provides the enzymes needed to ferment and break down soybeans to turn them into miso and soy sauce. It can also be used to create Amazake and curing agent for dry-aging meat and pickling vegetables.
Yield: approximately 1.3kg finished Rice Koji
Fermentation time: 48hrs
Ingredients:
- 1kg uncooked rice
- 2-3g Koji Starter (aka Tane-Koji) (Aspergillus oryzae)
Water for soaking and steaming
Equipment:
- Small mesh strainer
- Fermentation tray
- Steamer pot or bamboo steamer
- Fermentation chamber for temperature control
Method:
Wash the rice until the water runs clear and soak the rice in water for at least 4hrs so it gets properly hydrated. Once the rice is hydrated, strain away the water and steam the rice in a steamer pot or bamboo steamer. It is also possible to steam the rice in a regular large pot by wrapping the rice in cheesecloth and placing it on an elevated plate so it is well above the water level inside the pot. Make sure to place a cloth underneath the steaming basket to avoid rice from falling through. Steam the rice over high heat for 40 minutes.
Once cooked, let the rice cool down to below 40°C and place it onto a fermentation tray (preferably a Cedar Wood Koji Tray). Sprinkle the koji starter through a small mesh strainer to evenly distribute the powder over the rice. Mix it well so all the rice grains are coated with the koji starter, then spread the rice evenly and thinly over the tray.
Place the tray of rice inside a fermentation chamber and set the temperature to 31°C for 48hrs. Set the fan speed to low and the humidity to about 75% RH, as you do not want the rice to dry out. If you cannot control the humidity, you can cover the tray with a damp cloth or plastic wrap to trap moisture. Setting the temperature to 31°C allows for proper inoculation while preventing the rice from heating itself up too much. Reaching above 40°C will kill the koji starter and inhibit mold growth.
After 48hrs, the rice koji will be done. You will notice a sweet aromatic smell that is nutty and fruity while seeing white fungus developed, like tiny delicate roots that bind the rice together, forming a cake of rice koji. Seeing this means you have successfully made rice koji!
This is how the koji spores are spread and interlinked at the bottom side.
