So I’m trying to make sake again after almost ten years. The last few times were a disaster–I barely got beyond the koji-kin, because it turned pink and smelled like nail polish. The sake itself was pee yellow, and I used sweet short grain rice to do it, so I knew that had to be wrong. This time, I’m trying to make sure I follow all the directions. I’m back at the koji stage, so I’m using the instructions on the back of the koji package.
My question is this: for those of you who make your own koji-kin, do you cover the inoculated rice with, say, a damp paper towel or cheesecloth as well as the container lid while you’re letting the spores do their thing? The Vision Brewing site says to, but the instructions on the back of the package don’t say anything about it. Neither does “Sake U.S.A.”, the book I’m currently using to finish the process ( the author doesn’t have much to say about making your own koji-kin, unless I’ve missed a chapter). So… help me out? What do you do?
Hello! Glad to hear you’re resuming your sake effort.
I think that choosing to cover the rice mass with a damp covering will depend on the moisture content of the rice and your ambient humidity. I don’t cover mine, but I do control the ambient humidity.
Generally, condensation on the rice, or any kind of surface water, is not very good for the koji. You want the mold to grow into the grain, not so much on the surface. That said, as long as the covering is damp, not soaking wet, it should just help the mass not dry-out, and will be fine. But it may not be needed.
Break the grain and you should see the level of growth inside it, approaching the center as the process finishes. Sweet and nutty taste and aroma should also be developing after awhile.
Assuming appropriate temperatures, I would say if you have clumping in the koji then you have enough (or maybe too much) moisture, and don’t cover with dampness. If its really fuzzy, you likely have too much. If you have grains drying out and becoming hard, or you see no growth in the grain, then maybe not enough moisture.
Hope that helps, good luck.
I may have had too much water, which is a bit odd, because I barely added any at all. The condensation in the container came from what was already there ( may have oversteamed the rice) and what was on my wet hands when I mixed the rice every ten hours. It’s been 40 hours now, and the rice smells good, but it’s mush (it looks like a gelatinous, somewhat solid pile of goo). And I don’t see any growth at all. Plus, I can hear what sounds like fermentation taking place (there is no yeast yet). Should I just start over?
ETA: I just tasted the mix. It tastes sweet, with the slightest amount of sour. I’m betting that’s coming from the fermentation. So I must be all right, even if I can’t see the mold. At least, I hope so 
I’m really late in responding. I never got a new post notification…
Did you decide to use it? Your koji is worth a try, I’d say. You may like the result. It’s a learning process at least.
A sour taste may indicate some bacteria influence. I don’t know. I’ve never heard sounds from koji. But having a pleasant smell and a sweet taste are both good things.
The growth can be discrete. Like i said earlier, I judge it based on the individual grain; it changes from a relatively translucent, rubbery white to a more opaque, chalky white as the growth heads inward. In a sticky mass, it’s likely just as happy growing in-between the grains.
Sticky, lumpy rice after the steam could be from not letting it drain long enough after soaking. I will spin the rice after hours of draining and still get drips out, it’s amazing how well it can hold on to the water.
Let the board know how it goes! I’m always happy to chime in when I have the time.
