Analysis of Acetate Ester Production in Wild Yeast to Identify Strains that Improve Flavor in Commercial Fermentation

Abstract

Craft beer has become a huge industry and every brewer is seeking a flavor blend that sets them apart. Small differences in flavor profiles in beer have been accomplished by varying ingredients, temperature, pitching rate, and top pressure, but differences in yeast gene expression may have a larger impact on flavor. The enzyme alcohol acetyl transferase I (AATase I) is encoded by ATF1 and catalyzes the reaction that produces acetate esters from ethanol and acetyl-CoA. The acetate esters have distinct attributes that are detected by smell and taste, and minute fluctuations in concentration can positively or negatively affect the flavor of the final product. In order to create commercial brewing strains that produce better tasting beer, we will take two different approaches. In the first approach we will collect yeast from the “wild” to compare to industrial strains. In the second approach we will induce mutations in ATF1 and its regulatory sequences to identify variations to generate commercial strains with an improved flavor profile. Our goal is to be able to unearth at least one viable strain for commercial fermentation use that will enhance the flavor of beer.