I have been thinking about how different koji compare with each other. The most meaningful way would be to compare sake made from each. However, I can’t do this at this time so I decided to look at the koji itself. The koji I looked at are: Cold Mountain, GEM Cultures, home made koji from GEM Cultures’ Koji-kin and SakeOne koji.
Both the Cold Mountain and GEM Cultures koji are quite dry and hard. When bit they are a little softer than dry rice but not by much. The home made and SakeOne koji are “fresher” and somewhat soft and chewy.
Cold Mountain and GEM Cultures seem less sweet than SakeOne which much less sweet then the home make koji. Given the minimal fuzz covering of the home made koji, I was surprised it was by far the sweetest. This seems to indicate a healthy amount of enzyme despite the lack of fuzz. To check to see how much the dryness is effecting the sweetness, I soaked some koji from each sample.
After soaking for an hour the water for Cold Mountain and GEM Cultures were a little sweet. The water for the home made koji was almost like syrup. However, the water for SakeOne was the least sweet. As for the koji itself, Cold Mountain was now the sweetest. GEM Cultures koji was noticeably sweeter but has a strong brand taste. Neither the SakeOne nor the home made koji seemed sweet any longer.