Characterization of the Key Aroma Compounds in Two Bavarian Wheat Beers by Means of the Sensomics Approach

Application of aroma extract dilution analysis (AEDA) on the volatiles isolated from a commercial Bavarian wheat beer (WB A) eliciting its typical aroma profile, best described by a clove-like, phenolic odor quality, revealed 36 odorants in the flavor dilution (FD) factor range from 16 to 4096. Among them, 2-methoxy-4-vinylphenol (clove-like) and 2-phenylethanol (flowery) showed the highest FD factors. AEDA of a second wheat beer (WB B), somewhat lacking the typical wheat beer odor note, revealed 32 odor-active components in the FD factor range from 32 to 8192. Among them, 2-phenylethanol, (E)-beta-damascenone (cooked apple-like) and 3-methylbutanol (malty) were detected with the highest FD factors. Next, all odorants evaluated with an FD factor >= 32 were quantitated by stable isotope dilution assays in both beers, and the odor activity values (OAVs; ratio of concentration to odor threshold) were calculated. Thereby, ethanol, (E)-beta-damascenone, 3-methylbutyl acetate, ethyl methylpropanoate, and ethyl butanoate showed the highest OAVs in WB A, followed by acetaldehyde, 3-methylbutanol, and dimethyl sulfide. In WB B, ethanol, (E)-beta-damascenone, ethyl methylpropanoate, ethyl butanoate, and 3-methylbutyl acetate showed the highest OAVs. Whereas most aroma compounds were present in the same order of magnitude in both beer samples, in particular, 2-methoxy-4-vinylphenol and 4-vinylphenol (smoky, leather-like) were by factors of 13 and 15, respectively, higher in WB A. For the first time, the overall aroma of wheat beer (WB A) was successfully simulated on the basis of 27 reference compounds in their natural concentrations using water/ethanol (95:5; v/v) as the matrix.