FORMATION OF ESTERS FROM ACIDS BY BREWER'S YEAST IV. EFFECT OF HIGHER FATTY ACIDS AND TOXICITY OF LOWER FATTY ACIDS

Open Access
Publisher Website
Google Scholar
Abstract
Fatty acids up to hendecanoic acid were inhibitors of formation of ethyl acetate in alcoholic fermentation with Saccharomyces cerevisiae (brewer's yeast). The higher acids were not inhibitory but stimulatory, possibly because they participated in synthesis of lipids, so sparing acetyl-CoA. The ethyl esters of lower fatty acids were distributed between the liquid phase and the yeast cells; the higher the molecular weight, the greater the extent to which the esters were bound to the yeast cells. On this basis, ethyl caprate seems to be the highest ester of fatty acids that can be expected in beer and wine. Fatty acids were toxic to the yeast, growth being most strongly inhibited by pelargonic acid. The growth inhibition caused by a lower fatty acid was to some extent neutralized by the addition of higher fatty acids or amino acids, the effect being increased by addition of both; this was explained by assigning the toxic effect of the lower fatty acids to their acyl-CoA-derivatives interacting in processes consuming acyl-CoA-compounds. In no case, however, was inhibition completely neutralized, indicating other toxic effects or an ineffective utilization of the higher fatty acids.