Some metabolic products of beer yeast and their significance in fermentation technology.

Drews, B., Barwald, G. and Niefind, H.J.

Abstract
The aroma components of beer are classified according to their sensory perception. Some of the technical factors which influence the formation and elimination of these substances such as vicinal diketones, esters, other carbonyl compounds, higher alcohols and volatile sulphur compounds are described as well as yeast type, pitching rate, wort aeration, fermentation temperature, length of lagering and fermentation under reduced pressure. The marginal and average values of German beers as well as the taste threshold values for these volatile compounds are reported. A short review of the formation of the volatiles in raw materials and the use of gas chromatographic detection methods in operation controls are also given.
Keywords: beer brewing fermentation metabolism survey volatile compound