The Influence of Yeast in Alcohol Distillation

yeast is a single-celled organism responsible for fermenting sugar into alcohol that we drink, producing delicious flavors like whisky phenolics. Although distillers know yeast’s role well, most consumers remain unaware of how these tiny fungi contribute to the taste of their favorite whiskies, beers or wines.

In the whisky industry, most distillers use commercial strains of Saccharomyces cerevisiae called M-type or Kveik from Kerry Bio-Science; both belong to Saccharomyces cerevisiae and have become standard since 1950s. Their yeast can efficiently ferment cereal-based wort into alcohol with high yields. Many whisky producers also utilize custom yeast strains designed to create their distinctive flavors; these may or may not be similar to what breweries employ but more often they produce high quality consistent products while producing low levels of phenolic off-flavors while withstanding physical or chemical environmental stresses.

Other microorganisms may influence the final flavour of new-make spirit by contributing phenolic or non-phenolic off-flavors (Watson 1981). As fermentation processes are not sterile, other bacteria and fungi may grow in the wash, decreasing sugar-to-alcohol conversion rate and providing off-flavors such as phenolic off-flavors (Watson 1981). Recent work using non-Saccharomyces yeast fermentations shows these strains may enhance flavor production and yields (Grba et al. 2002 / Fonseca et al. 2011).