Good Chemistry: Flavoring beer with common beer esters

Although it may seem otherwise, it actually is not magic that gives certain beers their fruity notes and aromas; It’s chemistry.

From full-bodied flavors of banana or apple, to subtle notes of passion fruit, mango or pineapple, alcohol esters are a naturally occurring result of esterification – a chemical reaction between acids and ethanol – during the fermentation process of beer.

There are four types of beer esters: Ethyl AcetateIsoamyl Acetate (banana), Ethyl Butyrate (passion fruit, pineapple, mango) and Ethyl Hexanoate (apple, anise).

The most common ester, Ethyl Acetate, is present in every type of beer. But because a strong presence of this ester in beer is not desirable, as it smells and tastes similar to nail polish remover, it is not classified as a “beer flavor”.

The Poetry of Esters” is a published compilation of poems written about beer esters by brewmasters. Seth Gross’s poem, “O’ Ester My Ester” does an excellent job at explaining the entire esterification process, very simply. Gross writes:

“There’s something on my mind regarding esters
If I don’t let out the thought it just festers

Chemical compounds with nuances of fruit
Aromas expelled when our yeasts toot

If you find your ale a little off or bland
Watch your pitch rates from the corny can

Keep your temperatures proper or at least up high
You’ll achieve the flavors that’ll make you cry

Tears of joy from apricots, pineapple and banana
Tears of pain if nail polish….
…Wipe your eyes with a bandana”

Gross is the owner of Bull City Burger and Brewery in Durham, N.C.

Craft beers are particularly special because of their advanced ester profiles, which include varying amounts of Isoamyl Acetate, Ethyl Butyrate and Ethyl Hexanoate.

For instance, Belgian beer is best known for having a banana taste and aroma, so brewmasters concentrate specifically on developing a Belgian’s Isoamyl Acetate ester profile.

Banana Beer Ale

Posted by Lakeside Liquor on Saturday, August 1, 2015


In contrast, many India Pale Ales (a.k.a. IPAs) have a more mango flavor.

Although the typical beer drinker may be unaware of these subtle fruity yeast bi-products, a beer’s ester profile is especially important to craft beer aficionados and beer snobs alike:

Even though beer esters do occur naturally, brewmasters and home brewers will often add more of a specific ester to achieve a desired taste.



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