Characterization of the Key Aroma Compounds in White Alba Truffle (Tuber magnatum pico) and Burgundy Truffle (Tuber uncinatum) by Means of the Sensomics Approach

Aroma extract dilution analysis of distillates prepared by solvent extraction and solvent-assisted flavor evaporation distillation from white Alba truffle (WAT; Tuber magnatum pico) and Burgundy truffle (BT; Tuber uncinatum) revealed 20 odor-active regions in the flavor dilution (FD) factor range of 16-4096 in WAT and 25 in BT. The identification experiments in combination with the FD factors showed clear differences in the overall set of key odorants of both fungi. While 3-(methylthio)propanal (potato-like) followed by 2- and 3-methylbutanal (malty), 2,3-butanedione (buttery), and bis(methylthio)methane (garlic-like) showed the highest FD factors in WAT, 2,3-butanedione, phenylacetic acid (honey-like), and vanillin (vanilla-like) had the highest FD factors in BT. Odor activity values (OAVs, ratio of concentration to odor thresholds), which were calculated on the basis of quantitative data obtained by stable isotope dilution assays, of >1000 for bis(methylthio)methane, 3-methylbutanal, and 3,4-dihydro-2-(H)pyrrol (1-pyrroline) revealed they are key contributors to the aroma of WAT. In BT, 1-pyrroline and 2,3-butanedione showed the highest OAVs of 1530 and 1130, respectively. Aroma recombination experiments successfully mimicked the overall aroma profiles of both fungi when all odorants showing OAVs of >1 were combined. Omission experiments confirmed the amine-like and sperm-like smell of 1-pyrroline, identified for the first time as a key odorant in both truffle species.