Rice, sorghum… and yeast?
OK, let’s suppose you observe a Pesach custom in which you avoid leavened foods made from the prohibited grains (including, difficult though it may be for a whole week,* beer). But you do not consider rice, sorghum, millet, chickpeas, and other ‘grains’ (and flours made from them) to be prohibited.
Now let’s suppose you regularly eat breads made with some of the above-mentioned, non-prohibited, flours. And, of course, yeast, so that the bread rises.
Is the bread thereby prohibited?
The same question applies to gluten-free beer (made from rice, sorghum, etc.).
I lean ‘yes’–it is ‘fermented’ and sure looks and tastes like the prohibited leavened breads (well, actually, better in some cases–though I would not say that about the beer).
But I’m not sure, given that it is not made of the basic grain ingredients that are the underlying definition of chametz.
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* And fortunately you follow the 7-day custom, not the 8-day!!