THE OCCURRENCE OF TWO GEOMETRICAL ISOMERS OF 2,4,5‐TRIMETHYL‐1,3‐DIOXOLANE IN BEER

Abstract

Two geometrical isomers of 2,4,5‐trimethyl‐1,3‐dioxolane have been detected in a range of commercial and experimental beers at levels up to ca 0.1 ppm. These compounds, plus a number of other dioxolanes, are present in unboiled wort but are lost by evaporation during wort boiling. The trimethyldioxolanes are then reformed during subsequent fermentation. The flavour threshold of a mixture of the two trimethyldioxolanes was found to be ca 0.9 ppm, at which concentration it produced in beer ‘phenolic’ and ‘astringent/drying’ flavour notes. However, these compounds are not present in sufficiently high concentrations to make a significant contribution to the flavour of beer. 1982 The Institute of Brewing & Distilling