Have you ever had a Bavarian weissbier or hefeweizen and thought to yourself, “this beer tastes like bananas!” For those of you that have, what you are actually tasting is a nifty little organic compound called Isoamyl acetate.
Isoamyl acetate is considered an ester, or a combination of an alcohol and an acid, and it is actually present in all beers. While beers do have a large variance in the amount of this compound, its flavor threshold rests somewhere between .6 to 1.2 parts per million.
It’s large presence in beer is dependent on the yeast strain and a high level of glucose in the original wort (unfermented beer). It can contribute to the banana like qualities of weissbiers and the fruity characteristics of high alcohol stouts, amber ales, and blondes. “As with other esters, it is produced by yeast during fermentation and has major flavor impact on certain beer styles, particularly Bavarian style wheat beers,” according to Beer & Brewing Magazine.
Isoamyl acetate occurs naturally in both the banana plant and as a honeybee pheromone, and has an incredibly pungent and recognizable banana flavor and smell. It can also be produced synthetically and has many practical uses outside of its use as a flavoring agent including airplane adhesive, a testing compound for gas masks, and in thermometers.
Next time you’re enjoying one of these styles, you’ll know that Isoamyl acetate is to thank for that amazing and unique banana flavor.