The use of atmospheric and room temperature plasma mutagenesis to create a brewing yeast with reduced acetaldehyde production

Abstract

High acetaldehyde levels in beer from yeast metabolism is a major concern for brewers in China. To obtain a strain with lower acetaldehyde production, this work reports a novel approach based on atmospheric and room temperature plasma mutagenesis and high-throughput screening using 4-methylpyrazole + disulphiram plating. A mutant LAL-8a with lower acetaldehyde-producing capability was obtained. The alcohol dehydrogenase activity decreased by 54% compared with the wild-type M14 and the aldehyde dehydrogenase activity increased by 64% of the wild-type strain. Through domestication and fermentation in EBC tubes, the mutant LAL-8a was shown to produce 2.2 mg/L acetaldehyde, 88.2% less than the wild-type strain M14. In addition, the ratio of higher esters to alcohols in beer fermented by the mutant LAL-8a (0.28) was higher than M14 (0.16). The fermentation performance of LAL-8a was similar to that of the wild-type M14. This work suggests strain LAL-8a a promising option for the brewing industry. © 2018 The Institute of Brewing & Distilling