Koji making

[Tim Hall]

Ideal humidity is probably 90-100%. If you want more humidity, you can put some soaked sponges or a tray of perlite soaked with water in there.

But I have a feeling the problem was the temp and/or too much competing bacteria. Next time you might take a little extra care to make sure your prep area, utensils, blankets/towels/whatever, are extra clean. Avoid using wooden/porous utensils that were used for other ferments. Bacteria grows much faster than fungi, and if you give them the advantage, they'll take over.

You may need to monitor the temp a little closer...it builds up over time. Cracking the lid on the cooler is one way to reduce temp. Other options get more technical/expensive. You might also try doing a "dry" run with your hot water bottles in the cooler (no koji) and just see where you're at. IIRC the ambient temp in the cooler starting out should be between 80-85F.

[anahatabalance]

Been making koji for a long time now. To correct Tim, koji is really a mold spore. Any thing sour smelling and having a poorly developed appearance means contamination. Gem Cultures instructions for making koji works, but are somewhat out of date. I use a food dehydrator(excalibur) to control the temp vs water bottles. Find trays that fit your dehydrator, cover rice filled trays with plastic or foil and place wet cloths on top of this to keep the rice from drying out. About every two to four hours you'll have to re-wet the cloths and stir the koji rice. Around 36 hours later you should see and smell the koji mold on the rice grains. Once the koji starts working you'll have to watch the temp, as the koji will start producing it's own heat. If the temp is to high you'll kill off the koji mold spores. The process is finished when the grains of rice turn "koji white" about 3/4 of the way through and has that great smell. Dried koji is just as active as fresh koji just last a longer time in storage.

I have reproduced koji spores but it is not easy as just buying a big batch of spores from someone online. You have to keep the temp and humidity correct and your white rice grains will turn green. This in turn can be ground to make a new batch of koji. Hope this answers some questions.

Nirinjan

[Tim Hall]

To correct Tim, koji is really a mold spore. Any thing sour smelling and having a poorly developed appearance means contamination.

That koji is a mold was not in contention, and culturing at above-normal temps (in addition to using contaminated vessels & utensils) is well known to give bacteria the advantage over fungal cultures. So I'm pretty sure that's what I said...

But I have a feeling the problem was the temp and/or too much competing bacteria...bacteria grows much faster than fungi [especially at elevated temps], and if you give them the advantage, they'll take over.

Nice to learn a new incubation method though.

If you are referring to my use of the term "fungal":
Mushrooms = multicellular, fruit-body producing fungi
Molds = multicellular, sporulating fungi
Yeasts = unicellular fungi

Generally speaking this is the order of things, fastest growing/multiplying, also going from least susceptible to contamination and temperature differential to most susceptible:
Bacteria>Yeasts>Molds>Mushrooms

[nkbrilley]

I made two batches koiji, one rice , one barley a few months ago, for the first time, using GEM cultures and their recipe. Very successful, no mention of plastic cover - that WOULD make it soggy, I covered with a tea towel (their suggestion) lint textile, i was actually worried about drying, so i did even add a tiny bit of water on the second day. We have an oven which can go down to 30C for bread proving - ideal, and using a cheap thermometer with thermocouple buried in the grain you can keep an eye on the temp to 0.1 of a degree.