Wash the barley 2-3 times or until the white dirt dissapears. To begin soaking, add a clean water until the barley is all soaked. The appropriate time to soak the barley in 20℃ water is about 1 hour. Since barley has fast speed of water suction, don’t soak it in water for a long time.
STEP 2. Drain water from the barley
Take the soaked barley with a strainer, and drain it for about 30 minutes. Make sure that all water were drained well. If there’s water left, the finished result will not be good barley koji.Also, if in the middle of draining process you stir the barley, or wipe the strainer, the surface of barley may be scraped into powder, causing stickiness. Please put the barley on strainer and leave it as it is when draining the water.
STEP 3. Steam the barley
Wrap the barley with steaming cloth and steam it for approximately 40-50 minutes. You can use instant pot (with steamer function), any steamer device, or bamboo steamer. The steaming process here affects the finished result of koji greatly, so let's be careful when steaming teh barley. Please steam the barley slowly and set the fire not too strong so the heat can nicely pass through the core of the barley.When steaming with weak steam for a long time, please be careful as it will become koji with high water content.
When the barley grain became translucent, elastic, there was no core when you pinch it, and its texture is just springy like a mochi, then the steaming condition is good.While waiting for the steaming process to be done, please prepare the koji fermenter device and warm it until 35℃
STEP 4. Sprinkle the koji seed (koji starter) on steamed barley (seeding)
Spread the steamed barley on a clean tray (※please be careful not to burn yourself because of the hot temperature). Cool off the barley's temperature by spreading it with rice paddle.Sprinkle the koji starter suitable for making barley koji when the temperature reaches 35-40℃. This steep is called “seeding”. Use a sieve to sprinkle the koji starter. After that, mix well.
Use 1g of koji starter for 500g of steamed barley. But, it’s easier to succeed the breeding of the koji starter if you use 3 to 4 times of that amount, so you can increase the koji starter quantity to increase the possibility of success.
After you finish the seeding, quickly gather the barley together and wrap it with a clean cloth.When wrapping it with cloth, wrap it roundedly as small as possible by applying force.
STEP 5. Keep the barley warm (18-20 hours)
Place the wrapped barley on the Kojibuta (Koji Lid/Koji Tray), then put it in the koji fermenter machine. Warm the barley for 18-20 hours. The optimum temperature of the surface of the barley is around 30-35℃.
STEP 6. Untangle the in-fermenting-process barley (First maintenance of koji)
After 18-20 hours of the first warming process, the temperature of barley will rise, and it will produce a sweet aroma of koji. When the temperature rises to about 38 to 40℃, take it out, untangle the clumps of the barley with both hands to lower the temperature of the barley.After that, wrap it in the cloth and put it again in the fermenter machine. Keep it warm for 5-6 more hours.
STEP 7. Second maintenance of koji
When 5-6 hours have passed from the first maintenance of koji, the koji starter will further breed, and the barley koji temperature will rise again to 36-40℃. At this moment, once more, quickly untangle the clumps of barley and stir the whole of barley koji. This time also, keep in mind to do the maintenance quickly so that the temperature of barley does not go down under 30℃. After the second maintenance of koji, keep it warm again for 19-21 more hours.
STEP 8. Completion of koji
After 19-21 hours from the second maintenance (42-48 hours from sprinkling the koji starter on steamed barley {seeding}), good quality barley koji is completed if it has a nice chestnut-like scent. The indication of the completion of koji is that if the hyphae of koji starter stretches out, the barley sticks to each other and becomes a plate shape, and easy to disentangle by hand.