Formation of Phenethyl Alcohol and Tyrosol during Fermentation of a Synthetic Medium lacking Amino-acids

Abstract

THE fusel oils, or the higher alcohols produced during fermentation, play an important part in the bouquet of wine and the flavour of beer¹. Since the classical studies of Ehrlich it has been thought that they are produced by degradation of amino-acids, and this point of view has gained considerable support from the recent work of SentheShanmuganathan^2,3. Nevertheless, Castor and Guymon⁴ have pointed out that the concentration of the appropriate amino-acids in grape must is insufficient to explain the level of fusel oils found in the wine, and when Genevois et al.⁵ found that 1-¹⁴C-sodium acetate is incorporated into 3-methylbutanol during fermentation they suggested that the bulk of fusel oil is produced from this or similar intermediates. In considering the formation of fusel oil during beer production it has been pointed out that although the amount of the various amino-acids present in wort and metabolized during fermentation is sufficient to account for the higher alcohols formed by the Ehrlich pathway, this is probably not the only route to these compounds¹.