I saw a recipe online that involved mixing miso paste into the soak water for rice, and gave it a try. In a one-quart Mason jar, I mixed one cup rice, three cups water, and a tablespoon or so of miso and let it sit out for about 24 hours, shaking it whenever I walked by it. After a day, there's been a nice frothy head on the mixture as one would expect to see from fermentation, and it re-forms pretty quickly after a good shake.
I just strained out the rice (which required the addition of a bit more water to get all the rice to pour out of the jar), reserved much of the liquid, and started a new soak of another cup of rice in three cups of the reserved liquid.
Am I risking any ill health effects from this? I know that B. cereus is particularly fond of rice, and I'm not looking to create a culture for that.
The rice is used for congee, which comes to a boil briefly and then simmers at lower temperatures for hours.
Does anyone have experience fermenting rice in miso?