two mason jars side by side, one labeled "siho koji" and the other "barley shio koji"

On March 29th, 2020, I put some rice and barley koji into separate mason jars with equal parts water and 5% salt. I left them on my kitchen counter and took a photo every morning for 30 days, after which I would stir and also taste each.

See the twitter thread below for the goods!

Some of my main observations and conclusions:

  • The affect of ambient temperature on the day-to-day activity was huge. This particular month in Cleveland had many highs and lows, most of them being of the weather variety.
  • Fermenting for one week and then refrigerating could very well result in a fridge bomb, as my rice koji was most active on day 8. As I noted in the thread, I’d recommend a minimum of 10 days.
  • The rice had a phase between about 2 and 3 weeks where it developed some astringency, but it dissipated by the end.
  • I really did not expect the barley to take on such bright and acidic flavors, and so quickly.
  • The barley shio koji is good, but there’s a reason that koji and rice were basically domesticated together. This stuff is really good. I’m salivating thinking about it now while writing this.

After being in the fridge for another half-month (being used here and there, mind you) the layer of hooch is becoming more prominent, and there’s a strong alcohol smell when opening it after any length of time. However, the taste has not been negatively affected so far.

A few days after the “observational study” ended, I marinated 2 steaks overnight, one with rice shio koji and one with the barley. In a strictly uncontrolled, highly biased setting, Jack and I had to really concentrate to detect the difference in flavor between the two. I wish I had done a control steak without any marinade to experience the difference that koji can make. I also wish that I had marinated the steaks longer for a more distinct experience, but these are just more tests that I’ll have to bring myself to run again.