I received this helpful info from London fermentation enthusiast Haidi Jenkin:
I thought you might be interested to share with your readers how the (seemingly ubiquitous) Instant Pot can be used for fermenting purposes. I have used mine for many different fermenting projects described in your books – for example:
Natto – you can cook your soy beans in the Instant Pot for 60 mins or so, drain then add Natto spores or wash out a pack of natto into the beans and use the Yoghurt normal setting to maintain the right temperature for 24h.Koji – to cook the rice the right way you can use a bamboo steamer in the base of the pot and a tea towel to elevate and wrap the rice during cooking – the bundle sits on the steamer out of the water which reduces how wet it gets. This is cooked on the Rice setting. Once cooled you add the koji spores, separate and wrap in two tea towels, and rest these bundles on top of the bamboo steamer keeping them off the water in the base of the Instant Pot (this water is needed for humidity so add some if it all got used up in the last step). You can then use the Yoghurt less setting and a tea-towel or bamboo lid on top of the pot, this maintains the right temperature, humidity and oxygenation for the first 24h. After this you can take the bundles out and leave them at room temperature since they will now need cooling vs heating.Amazake – the Keep Warm less function keeps the amazake mix (koji + rice + water) at just the right temperature for the 10h you need to develop the amazake.Dosa batter – Yoghurt less is again good for this, probably this would suit many fermented batters such as injera particularly during the winter.Your readers might be interested in the Instant Pot temperature specs for these settings:Yoghurt less – 30-34 degrees C / 86-93.2FYoghurt normal – 36-43 degrees C / 96.8-109.4 FKeep warm – 63-78 degrees C / 145-172 F