How to make Koji rice at home 쌀누룩 만들기

Koji is a cooked rice inoculated with a bacteria called Aspergilus Oryzae.
Koji is a good first step to many elaborately processed foods and beverage.

Koji can be used in making your own Makgeolli, Sake, Miso paste and pickles. Furthermore, you could marinade your meat with Koji to give aged taste and soften the meat as well. Koji can be added on your food directly as a form of Koji salt (Kojishio) or Koji Soy sauce ( Kojishoyou) to give extra boost of umami flavour to your food.

Nowadays you could purchase your Koji rice from online or from your local shop easily, However I find using house made koji gives so much better result on the product you make. Plus It is not hard to make at all.

[Ingredients]
1kg Calrose rice (sushi rice)
5g Koji Spore

[Method]
IMPORTANT! Every steps you follow, make sure using sanitised utensils, trays and hands. If you don't use clean hands or tools, its easy to get contaminated with bad bacteria. You can purchase an alcohol for food industrial use or Starsan for brewing from the shop. If you dont have the any of them, make sure to sanitise in the boiling water for few minute or steam over 100c for few minutes.


1. Wash the rice thoroughly several times, until the water is almost clear.
2. Soak the rice for overnight. (Frankly, after 3 hours of soaking the result is same. you could do soak it for 3 hours if you have time for the whole process)
3. Drain the rice for 1 hour
4. Lay out the rice on the steamer tray ( make a few holes) and Steam the rice for 30mins and take it off the heat, and rest for another 20mins. (Depends on your steamer condition, the process might take longer. The rice should be just cooked but it shouldn't under cooked inside. Looking for nice fluffy rice)
5. Weight out 15g of Rice flour and 5g Koji spore
6. Place the rice in the clean sanitized tray and quickly cool down the rice to just under 40c. (35~38c)
7. Add rice flour and koji mixure into the rice and mix up with rice properly. Make sure spreading out properly.
8. Cover with a wet cloth and move it to a fermentation chamber.
9. My fermentation chamber is set at 30~33c and humidity 70%. If you don't have a proper set up, you could use your oven with pilot light on with tray of water at the bottom for humidity. Make sure keep eyes on the temperatures.

AFTER 12 HOURS

10. Check the temps of rice, its going well if its around 30~32c. Mix up rice gently so heat inside can be escape. and Check after another 24 hours.

AFTER 24 HOURS

11. You should be able to see white mold starts to bloom a bit, Again, mix up rice gently.

AFTER 36 HOURS

12. Repeat the process.

AFTER 48 HOURS

13. Your Koji rice should be bloomed with healthy white mold and has smell of fruity aroma.
14. Koji should be ready around this stage, if you leave for another 24 hours it will turn to green spore which is the Koji spore you used. So if you are looking to get more koji spore, you could leave another 24 hours.
15. Now dry your Koji rice in the oven with light on for 2-3 days depends on how moist your koji is.
16. After dry out, Vacuum seal with food saver or Store in a Zipper bag and store in the freezer until you would like to use the koji rice.