Isoamyl alcohol

An aliphatic alcohol of characteristic odour and pungent taste; isopentanol, methyl butanol, and isopentyl alcohol are its synonyms. Esterification uses it as a substrate for producing isoamyl esters, and it also appears commonly among the aroma compounds in wines, cider, and beer through yeast fermentation. At moderate levels it adds complexity to the fermentation bouquet; in excess it turns harsh and solvent-like, marking stressed or faulty fermentations. Distillers watch its level closely because it shapes both flavour and spirit fractions.