Characterization of volatiles in unhopped wort.

The volatile fraction of wort components was studied during boiling. Not less than 118 volatile compounds were identified when unhopped pilsner wort was boiled and samples of wort and condensed vapors were analyzed with headspace SPME-GC/MS, of which 54 were confirmed with reference compounds. The wort samples contained 61 identifiable compounds, while the vapor condensate yielded 108 different compounds. Almost 30 known compounds were found that have not been described before in unhopped pilsner wort. One previously unknown aldol reaction product was tentatively identified as 2-phenyl-2-octenal. The detection of branched 2-alkenals underlines the importance of the aldol condensation in Maillard-type reactions, while the tentative identification of alkyloxazoles and alkylthiazoles could once more accentuate the central role of alpha-dicarbonyl compounds, aldehydes, and amino acids in flavor generation. The condensation of wort vapors joined with the SPME-GC/MS technique has proven to be a useful tool in volatile analysis.