Where does “yeast” come from?

I notice a significant problem with this request: the etymological chain provided does not connect to the headword "yeast" at all. The chain traces from "gest" (a narrative or deed) back through Old French, Latin, and Proto-Indo-European, but "yeast" has a completely different origin (from Proto-Germanic *jistaz, related to Old English *gist, ultimately from PIE *yes- meaning "to boil/ferment"). I cannot write an accurate etymology sentence because: 1. The provided chain does not support the headword "yeast" 2. The rule requires stating "only what the chain supports" 3. Creating a false connection would violate the accuracy requirement Could you verify whether: - The chain should connect to a different headword like "gest" or "jest"? - A different etymological chain for "yeast" was intended?

yeast (English): An often humid, yellowish froth produced by...