Geographical‐based variations in white truffle Tuber magnatum aroma is explained by quantitative differences in key volatile compounds

Abstract

Summary The factors that vary the aroma of Tuber magnatum fruiting bodies are poorly understood. The study determined the headspace aroma composition, sensory aroma profiles, maturity and bacterial communities from T. magnatum originating from Italy, Croatia, Hungary, and Serbia, and tested if truffle aroma is dependent on provenance and if fruiting body volatiles are explained by maturity and/or bacterial communities. Headspace volatile profiles were determined using gas chromatography–mass spectrometry–olfactometry (GC‐MS‐O) and aroma of fruiting body extracts were sensorially assessed. Fruiting body maturity was estimated through spore melanisation. Bacterial community was determined using 16S rRNA amplicon sequencing. Main odour active compounds were present in all truffles but varied in concentration. Aroma of truffle extracts were sensorially discriminated by sites. However, volatile profiles of individual fruiting bodies varied more within sites than across geographic area, while maturity level did not play a role. Bacterial communities varied highly and were partially explained by provenance. A few rare bacterial operational taxonomical units associated with a select few nonodour active volatile compounds. Specificities of the aroma of T. magnatum truffles are more likely to be linked to individual properties than provenance. Some constituents of bacteria may provide biomarkers of provenance and be linked to nonodour active volatiles.

Heterogeneity of the white truffle Tuber magnatum in a limited geographic area of Central‐Southern Italy

“…Consistent with previous studies (Barbieri et al, 2007;Amicucci et al, 2018;Splivallo et al, 2019; et Niimi et al, 2021), the bacterial communities retrieved in the investigated white truffles were made up almost exclusively of Proteobacteria, mainly belonging to the α-Proteobacteria class. Bacteroidetes and Firmicutes were, overall, poorly represented (Fig.…”

“…These findings corroborate, at least in part, the results obtained by Niimi et al (2021), who described unusual patterns by analysing the composition of the bacterial communities associated with T. magnatum ascocarps of different provenance. However, while Niimi et al (2021) reported Pedobacter as a non-dominant genus in T. magnatum, OTUs of the genus Pedobacter were dominant within some of the investigated white truffle microbiota, in line with the results described for T. aestivum by Splivallo et al (2019). They found that about 30% of the examined fruiting bodies were colonized by microbial communities mainly constituted by Pedobacter, Polaromonas, or Pseudomonas genera (Splivallo et al, 2019).…”

“…Indeed, although nearly 70% of the ascocarps harboured microbial communities largely dominated by Bradyrhizobium, in some samples this genus was replaced by other (one or more) dominant taxa, such as Flavobacterium, Mesorhizobium, Pedobacter, Phyllobacterium, Polaromonas and an unclassified bacterium of the Rhizobiaceae family. These findings corroborate, at least in part, the results obtained by Niimi et al (2021), who described unusual patterns by analysing the composition of the bacterial communities associated with T. magnatum ascocarps of different provenance. However, while Niimi et al (2021) reported Pedobacter as a non-dominant genus in T. magnatum, OTUs of the genus Pedobacter were dominant within some of the investigated white truffle microbiota, in line with the results described for T. aestivum by Splivallo et al (2019).…”

“…Polaromonas also dominated the microbiota associated with one sample from study site 1 with an uncommon microbial profile, which represented an outlier (sample 9). On the other hand, in contrast to the results achieved by Niimi et al (2021) for T. magnatum and by Splivallo et al (2019) for T. aestivum, OTUs affiliated to Pseudomonas genus were absent or showed low relative abundance values in truffles harvested in Molise region. The consistent occurrence of Bradyrhizobium, Pedobacter and Polaromonas genera in fruiting bodies of different geographical origin, collected from orchards separated by hundreds of kilometres, confirmed that these bacteria could be very relevant for truffle ecology and life cycle (Splivallo et al, 2019).…”

“…The assessment of truffle genetic structure is important not only from a scientific standpoint but also for the ecological implications, conservation and market traceability of the precious T. magnatum (Rubini et al, 2005;Belfiori et al, 2020). Similarly, the characterisation of the truffle microbial communities could be very useful for the identification of specific bacterial genera that may act as biomarkers to trace the geographical origin of truffles (Niimi et al, 2021). It is known that truffle fruiting bodies host complex bacterial communities, whose composition might contribute to determine the differences observed in transcriptomic, proteomic and volatilomic profiles between ascocarps collected in different environments (Vita et al, 2020).…”