VIEW ARTICLE    DOI: 10.1094/ASBCJ-53-0153

Yeast Strain Development for Enhanced Production of Desirable Alcohols/Esters in Beer. Sun Lee, Keith Villa, and Hugo Patino, Research and Development Department, BC-600, Coors Brewing Company, Golden, CO 80401. J. Am. Soc. Brew. Chem. 53(4):153-156, 1995. Accepted April 24, 1995.

Bottom-fermenting brewing yeast, Saccharomyces uvarum, was induced to produce higher levels of desirable alcohols and esters (isoamyl acetate and phenylethyl acetate) in beer by selection on media containing amino acid analogues 5,5,5,-trifluoro-DL-leucine and fluoro-DL-phenylalanine, respectively. The isolated mutants have apparently lost their ability to regulate amino acid biosynthesis by means of feedback repression of the key enzymes in these pathways, which resulted in over-production of the corresponding keto acids. After decarboxylation and reduction, the resulting alcohols were esterified by alcohol acetyltransferase. Three-and nine-liter laboratory fermentations showed that selected mutants produced substantially greater amounts of alcohols, as well as their corresponding esters, in beer when compared with the parental strain. It is suggested that changing the regulation of key enzymes in amino acid synthesis can be used for the enhancement of desirable alcohols and esters in beer. Keywords: Isoamyl acetate, Isoamyl alcohol, Phenylethyl acetate, Phenylethyl alcohol