Beer cellar science: Esters (Part 1)
By jason on Aug 20, 2007 in Cellaring Science, Featured
Time for more beer science! I know you’re all so excited! Let’s talk about esters.
Esters are a class of compounds typically formed in a condensation reaction (whatever that is) between an acid and an alcohol. Esters in beer are by-products of the yeast fermentation process, which is why they are an important component of a beer’s flavor profile. They’re responsible for the fruity tastes and smells we often associate with our beers.
Unfortunately, many of the esters in beer are of a rather volatile nature, and will readily break down over time. Many studies have been done tracing the reduction in concentration of these tasty molecules, showing how they can disappear to the point of not being able to be tasted in a fairly short period of time. A well-known study traced one ester named isoamyl acetate, responsible for banana and pear flavors and smells, and watched it all but disappear out of a Belgian ale over the course of a year.
Many of these fruity flavors that are disappearing aren’t even part of the major flavor component of the beer. They’re more often background flavors, bit players adding their complexity and body to the brew. Even if you’re not consciously tasting their flavor all of the time, you start to miss them when they’re gone. Beer can taste flat and stale without them.
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