Characterisation of aroma active compounds in black truffles (Tuber melanosporum) and summer truffles (Tuber aestivum) by gas chromatography–olfactometry

The aromatic composition of two different species of truffles (black and summer) was evaluated by gas chromatography–olfactometry (GC–O). Volatiles released by the truffles at 25 °C for 7.5 h were collected in a trapping system consisting of 400 mg of LiChrolut EN kept at 0 °C and further eluted with dichloromethane/methanol (95:5). The extract was analysed by two different GC–O strategies: (1) a semiquantitative GC–O study using a panel composed of nine individuals, (three of them truffle experts) and (2) an AEDA (aroma extract dilution analysis) experiment with a small panel of two judges. The results show that the aroma emitted by a typical black truffle is due to at least 17 different aroma molecules, six of which are reported for the first time: 1-hexen-3-one, 2-methyl-3-furanthiol, furaneol, 3-ethylphenol, 3-propylphenol and 5-methyl-2-propylphenol. The most important aroma compounds of black truffle aroma are 2,3-butanedione, dimethyl disulphide (DMDS), ethyl butyrate, dimethyl sulphide (DMS), 3-methyl-1-butanol and 3-ethyl-5-methylphenol. Quantitatively, black truffle emits mostly 3-ethyl-5-methylphenol (more than 50% of the total aroma molecules emitted), 5-methyl-2-propylphenol, β-phenylethanol and 3-ethylphenol. In the case of summer truffle, the most important aroma molecules are DMS, DMDS, methional, 3-methyl-1-butanol, 1-hexen-3-one and 3-ethylphenol. From the quantitative point of view, summer truffle emits mainly β-phenylethanol, DMS and 3-ethylphenol, but the emission is up to 100 times less than that of black truffles.