Sulfur volatiles of microbial origin are key contributors to human-sensed truffle aroma

Abstract

Truffles are symbiotic fungi in high demand for the aroma of their fruiting bodies which are colonized by a diverse microbial flora. Specific sulfur containing volatiles (thiophene derivatives) characteristic of the white truffle Tuber borchii were recently shown to be derived from the bacterial community inhabiting truffle fruiting bodies. Our aim here was to investigate whether thiophene derivatives contributed to the human-sensed aroma of T. borchii. Furthermore, we questioned whether the concentration of thiophene volatiles was affected by freezing or whether it differed in truffles from distinct geographical origins. Gas chromatography-olfactometry (GC-O) analysis revealed that thiophene derivatives were major contributors to the aroma of T. borchii. Of four thiophene derivatives detected in this study, 3-methyl-4,5-dihydrothiophene was the most important one in terms of its contribution to the overall aroma. The relative concentration of thiophene derivatives was unaffected by freezing; however, it differed in samples collected in distinct geographical locations (Italy versus New Zealand). The causes of this variability might be differences in storage conditions and/or in bacterial community composition of the fruiting bodies; however, further work is needed to confirm these hypotheses. Overall, our results demonstrate that thiophene derivatives are major contributors to the human-sensed aroma of T. borchii.