Experiments in tempeh--and why the rice?

I haven't made tempeh in years, but I got sick of all the beans I've been consuming through the pandemic, so I used a gift card to procure some tempeh starter. I didn't want to use all the plastic that I'd used with my previous tempeh making endeavours, and one day I had a brilliant shower thought: if the traditional method for making tempeh called for wrapping the beans in banana leaves, might I be able to emulate that with materials I had on hand? Well, parchment paper was breathable, just like the leaves, and it could be wrapped around the beans to help them hold their shape until the mycelium could hold it all together.

I started a batch of black bean tempeh wrapped in parchment, and so far it seems to be going swimmingly. In a few months, after my achira is producing well, I might abscond with a few leaves to use in place of the banana leaves (and eventually I might actually have some hardy bananas to use.)

I love tempeh, and the only reason I stopped making it is because I ran out of starter and just never bothered to get more. This time around, I'm determined to keep my starter going. To that end, I've got questions.

First of all, why the rice?

(I know The Art of Fermentation has a section of tempeh, and I have it on hold at the library, but I don't want to wait 2 months just to find out that the answers I seek aren't in there.)

I assume that the reason rice flour is included in instructions for making tempeh starter, or why the tempeh fungus is allowed to grow onto rice first, is because rice is an easily digestible food source that allows it to get established quickly. But is it necessary?

Is there any reason why I couldn't crumble some fresh tempeh into a fresh batch of beans to keep it going? Or simply dry some tempeh and powder it without adding any rice? Would such techniques fail completely, or merely increase the odds of contamination, or what?

If it's necessary, might some other grain be substituted for the rice? I can't grow rice, so how would I maintain my starter in the proverbial apocalypse? Could I feed it on wheat, oats, amaranth?

I'm planning to crumble some of my fresh tempeh into a fresh batch of beans tomorrow to experiment, unless someone prevents me from reinventing the wheel. I swear I heard of that exact technique being used years ago, but now I can't find any examples of people doing it that way.

Hi, friend! I hope your tempeh journey is still going strong! I just started a fresh batch in recycled parchment paper and came here to see if anyone else had success in using parchment vs plastic. I have had success in using rectangular glass bowls. However, I wanted to get a tighter pack, so I'm currently waiting to see how the parchment does.

I have seen dehydrated tempeh slices powered and used as starter, so that is my plan, to save a piece from each homemade block to dehydrate and store for future tempeh-making practices.

Really excited and grateful.

Are you still making tempeh? I know it's been 2 years since your original post lol.

Peace