Koji
Temperature comfort zone: 27-35C Starter grains: long grain rice, polished sushi rice, pearled barley
Cook the rice or beans al dente. For rice, add slightly less water to the rice cooker than you would for eating. For beans, they should be soft enough to easily crush between thumb and ring finger.
Preparing the spores
Mix with flour to make it easier to disperse the spores in the substrate.
- Toast rice flower in a pan over medium heat until lightly browned (ca. 5 min).
- Remove flour from heat and let cool down.
- Add the right amount of spores to the flour.
Incubation
Koji likes humidity, so use a damp cloth to cover or plastic wrap. Check the humidity regularly and maybe add a bowl of water or a damp towel.
27-29C is best for savoury applications, as more proteases (rather than amylases) are produced by the fungus which give umami flavours. Stir every once in a while (every 24h or so) to distribute oxygen and heat, and loosen up clumps. But make sure to not dry out the substrate too much!
Best time to start to be able to monitor:
- Cook rice at 18:00, inoculate at around 20:00.
- Check temperature throughout the next day: 8:00 (=12h), 14:00 (=18h), 20:00 (=24h).
- Disperse and keep monitoring temperature: 8:00 (=36h), 12:00 (=40h), 22:00 (=50h).
During the first 12-18h: Set the incubation chamber to 29-31C. Usually you have to heat during that time and the koji can be placed in a thicker layer or even wrapped in towels to keep the temperature cosy and warm. Later on, the koji generates enough heat to stay at the right temperature (or might even need dispersing). Check the internal temperature of the koji every few hours and check the moisture levels.
After 18-24h: Fuzzy white coating appears. Pleasant yeasty, floral, sweet scent. Disperse heat by spreading out and stirring with clean hands or a clean spoon.
After 40-50h: Koji looks cottony and fuzzy and almost a little blurry. It’s done! Stop before any sporulation (yellow-green patches) is visible, as this will result in bitter/dank taste.
Storage
- Use immediately
- Store in fridge for up to 10 days.
- Store in freezer for up to 2 months.
- Dry immediately (at low temp, e.g. 30C for 7h in a dehydrator) for storage up to a year in the freezer.