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Will my koji drown?

Being new on the subject of sake-making I permit myself to bluntly put forward a foolish question. Just to help me understand the process a little better. I’ve not made any sake yet, but I am planning to. And I’m a bit confused here. . . As I understand from things I’ve read sofar, the idea is to first carefully make a koji-culture and then to drown the whole thing in water (and yeast and more rice).
I mean. . .Will the process of turning starch into fermentable sugars (by Koji) continue EVEN when the Koji is being comletely drowned in the water/rice/yeast mixture? Won’t it die?

By the way, Hello to you all, I am a beer-brewing enthousiast from Holland, developing an interest in sake-making.

Hello and welcome to our Sake community :smiley:

The koji process would be completed in 3 days, ending in a white-ish mold-rhined rice grains. At this point the koji mold growth is stopped/complete for Sake making.

The brewing of Sake simply takes advantage of this koji for the enzyme content and aesthetically for flavor. So technically your koji will not just be drowned, but water-logged and broken up. The enzymes from the koji dissolve into the water additions. The added steamed rice (gelatinous starch) will absorb the enzyme rich water. This makes the starch matrix in the steamed rice become exposed to amylase (starch to sugar converting enzymes) creating mostly glucose.

The yeast will eat the glucose to give us Sake. It’s the continuous break down of starch by the enzymes and the metabolism of the yeast relationship that makes Sake so special.

In beer, malted barley has much of its starch still in the grain and enzymes.

With Koji, it took another organism to make the enzymes so the starch is much less in the koji-rice vs steamed rice. I would hazard a guess there are more enzymes in the koji than the barley. By looking at typical Sake rice/koji ratio’s, koji can convert alot more by weight than malted barley to adjuncts/unmalted barley.

I hope this will help you, and good luck!


Thanks Dray!

Your reply helped me a lot.
I suppose I’ll be back with more Noob-questions shortly.


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