A Good Piece on the Subject of Esters…

The Poetry of Esters

The Poetry of Esters

No matter how seriously you take craft beer, you’ve likely come to understand that it’s a cerebral beverage that can push your palate to places it has not gone before. To me and millions of others, craft beer forces thought provoking, descriptor rich, passionately deep conversations that are often reserved for discussion and appreciation of things like art, sports and food. With that intro, let us explore the beauty and wonder of esters, yes esters!

Q: So what the heck are esters anyway?

A: A family of fruity smelling metabolites created by yeast during fermentation that are perceived in the aroma and flavor of craft-brewed beer.

While this answer seems pretty bland and boring, there’s much poetry behind this yeasty variable.

I argue that not being aware of beer’s yeast-derived offerings, such as esters, is like hearing a song in the background at a shopping mall compared to sitting in your favorite chair listening to the same song with headphones and picking out prominent instruments and vocals. Like with music, it’s possible to decipher how each element in a craft beer adds layer upon layer of influence to the whole gorgeous production.

Yes, esters play a starring role in my beer appreciation—oh yes they do! It’s rewarding to connect the dots on abundant flavors and aromas in beer from yeast including esters, phenols, diacetyl, acetaldehyde, alcohol and more.

“They [esters] give a soul to the beer,” said Chad Henderson, head brewer of NoDa Brewing Company in Charlotte, N.C. “I view malt as the backbone of the beer, but the esters are what give the beer definition. They play a different role in different beers, but the yeast by-products, mainly esters, have a place in beer and give it a character that you come to expect from that style. Some styles are way more dependent on this character. For example, Belgian beers, can have the most basic malt and hop bill but the esters open a whole world of flavors up for these beers. The rest of the beer is there to serve center stage to the yeast for beers like this.”

Q: What is brewer’s yeast?

A: Yeast is the living organism that turns water mixed with malt and adjuncts (fermentables that provide sugar) into fermented beer. The yeast eats sugars and produces carbon dioxide (the gas that makes up beer’s bubbles) and alcohol. Over 600 different kinds of yeast have been documented, though four create the majority of the different beer categories, with many variations among them: ale, lager, brettanomyces and weizen.

The Physiology of Esters

Generally, fruity esters occur more frequently as a result of higher fermentation temperatures (above 65°F), and thus are more common in ales. Most lagers (usually fermented at 50°F or below) do not contain enough esters to perceive. The level of esters and type of esters in a beer will depend on yeast strain used, fermentation temperature and other variables. For example, beers fermented with true German weizen yeasts contain a characteristic banana aroma. The banana esters, by the way have their own category: isoamyl acetate, and are what make Bavarian wheat beers famous.

In Garrett Oliver’s Oxford Companion to Beer esters are more geekily explained: “…during yeast fermentation ethanol (a form of alcohol) reacts with carboxylic acids to produce esters”. Esters are uncommon (and discouraged) in German and U.S. lagers, but are common and usually welcome to some degree in most ales.(Craftbeer.com)


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