After making 8 batches of rice koji, I’ve been making some barley koji too. The barley I use is slightly polished so that the aspergillus mold can penetrate the hull and the bran.

I follow the same procedure as I described in rice koji making earlier. There are, however, slight differences in odor, color, growth etc. The main difference in my procedure is that I use wooden (ash wood) boxes without lids, because these keep a better balance between air and moisture that is just right for the steam cooked barley.

The mold grows faster and flowers early on the second day. Still, I let it grow about 48 hours as with the rice.

The color at flowering (sporulation) is a rich greenish-yellow tan. When harvesting the koji, a cloud of mold spores rises, so do it carefully. Dry it and package it for later use in making barley miso.