The behaviour of volatile aromatic substances as beer ages

It has been possible by means of multidimensional gas chromatography with mass spectrometry to detect further aromatic substances which show a significant increase as beer ages unlike in previous studies. The detectable range of aromatic substances can be classified according to the already known ageing indicators. Over and above this their substances were subdivided into those that showed a strong increase at the beginning of the beer ageing process and those with an increased concentration in the advanced ageing stage. The first substances are used in the calculation for the dimensionless,,forcing index"; the latter were classified under the,,ageing index" with the incorporation of Strecker aldehydes and furfural. When following the beer ageing process there was a natural growth in carbonyls which were, however, weakened by (fermentation)SO,. Even oxygen heterocyclic substances such as furane and furanone occur more in aged beer. (E-)2-nonenal could not be confirmed to be the leading component responsible for the ageing of beer.