Making Koji rice using a koji starter culture is a fascinating process that combines tradition with the science of fermentation. Here's a step-by-step guide to help you get started:

Ingredients and Equipment:


  1. Soak the Rice:

    • Wash the rice thoroughly until the water runs clear.

    • Soak the rice in water for about 6-12 hours.

  2. Steam the Rice:

    • Drain the soaked rice and steam it until it's fully cooked but still firm. This usually takes about 45-60 minutes. A rice cooker can be used.

    • Ensure the rice is not too wet, as excess moisture can hinder the growth of the koji mold.

  3. Cool the Rice:

    • Spread the steamed rice on a clean tray to cool down. The ideal temperature for inoculation is around 30-35°C (86-95°F).

  4. Inoculate with Koji Starter:

    • Once the rice has cooled to the desired temperature, sprinkle the koji starter culture evenly over the rice.

    • Gently mix the rice to distribute the spores uniformly.

  5. Fermentation Setup:

    • Spread the inoculated rice evenly in the 2L yoghurt maker jar (lined with a clean dried cloth)

    • Cover the rice with the cloth to maintain humidity and prevent it from drying out.

  6. Incubation:

    • Place the 2 L jar in the yoghurt maker. The ideal temperature for koji fermentation is around 30-35°C (86-95°F).

    • Maintain a relative humidity of around 70-80% 

  7. Monitoring:

    • Check the rice every few hours to ensure it remains moist and at the correct temperature.

  8. Fermentation Duration:

    • The fermentation process typically takes about 40-48 hours.

    • During this time, you should see white mycelium spreading across the rice. The rice will start to emit a sweet, fragrant aroma.

  9. Completion:

    • The koji rice is ready when it is fully covered in white mycelium and has a sweet smell.

    • If the rice develops green or black spots, it means undesirable molds have grown, and the batch should be discarded.

  10. Storage:

    • Once the fermentation is complete, you can use the koji rice immediately or store it in the refrigerator for up to a week.

    • For longer storage, you can dry the koji rice and keep it in an airtight container. You can freeze and store for  up to 3 months.



  • Hygiene: Ensure all equipment and surfaces are clean to prevent contamination.

  • Patience: Koji fermentation requires patience and attention to detail. Monitor the process closely.

By following these steps, you'll be able to create your own Koji rice, which can be used for making miso, soy sauce, sake, amazake and other fermented foods. Enjoy the process and the delicious results!

Feel free to ask if you have any questions or need further assistance in your fermentation journey.