Esters and Phenols:

Yeast is one of the most important ingredients in beer, converting malt sugars into CO2 (the bubbles in your beer) and alcohol (the FUN in your beer).  But alcohol and CO2 aren’t the only things that yeast creates during fermentation.  Yeast can also create compounds called “esters” and “phenols” that add fruity and spicy flavors to your finished brew!

Typically, esters and phenols are more pronounced in ale styles, a perfect example being the German Hefeweizen.  This traditional German ale is bursting with notes of banana and clove, neither of which come from fruit or spice additions in the brew.  No, both of these flavors come from esters and phenols created by yeast!  No wonder they named the beer Hefeweizen considering hefe translates to yeast in German. 

Isoamyl Acetate is the ester responsible for the banana flavor in the Hefeweizen, whereas 4-Vinyl Guaiacol is the phenol responsible for the clove flavor.  If you’re reading this at our Octoberfest celebration, be sure to visit our interactive wall of esters and phenols in the large tasting room and give them a sniff!