How to Make Bokashi Grains
While white mold growth on the bokashi grains towards the end of fermentation is a good sign (green, blue and black molds mean you should dump the batch and start over), Aspergillus oryzae, or koji—the same beneficial mold use to ferment sake, miso, and several other food products—will also grow on your spent grain. Koji is especially useful as a bokashi EM addition if your food scraps contain a lot of starch, as the amylase will make quick work of pasta, bread, rice, or other grains. (Technically, you can grow pure-culture koji mold on sterilized spent grains in an incubator with the correct time, temperature, and humidity and then use those grains to make sake, but that’s a fairly elaborate process that’s better left for another ferment.) If you want to just add koji to your bokashi cocktail of EM, which will include lots of LAB if you’re pulling wet spent grain directly from the mash tun, simply sprinkle some koji-kin spores on the grains along with your other seed cultures.