compound
Isoamyl acetate
The ester responsible for banana aroma — the signature of Bavarian wheat beer and a defect in a pilsner.
Production rises with fermentation temperature, with pitching rate (lower pitching means more growth and more ester) and with wort gravity. All three are levers a brewer can pull deliberately.
Evidence
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Yeast ester production rises with fermentation temperature, with wort gravity and with under-pitching, which is why the same strain produces a clean beer at 18 °C and a banana-forward one at 24 °C.
Backed by a source
Sources: Yeast: The Practical Guide to Beer Fermentation — print; Brewing: Science and Practice — print