Potential aromatic compounds as markers to differentiate between Tuber melanosporum and Tuber indicum truffles

Abstract

The Tuber indicum (Chinese truffle) and Tuber melanosporum (Black truffle) species are morphologically very similar but their aromas are very different. The black truffle aroma is much more intense and complex, and it is consequently appreciated more gastronomically. This work tries to determine whether the differences between the aromatic compounds of both species are sufficiently significant so as to apply them to fraud detection. An olfactometric evaluation (GC-O) of T. indicum was carried out for the first time. Eight important odorants were identified. In order of aromatic significance, these were: 1-octen-3-one and 1-octen-3-ol, followed by two ethyl esters (ethyl isobutyrate and ethyl 2-methylbutyrate), 3-methyl-1-butanol, isopropyl acetate, and finally the two sulfides dimethyldisulfide (DMDS) and dimethylsulfide (DMS). A comparison of this aromatic profile with that of T. melanosporum revealed the following differences: T. indicum stood out for the significant aromatic contribution of 1-octen-3-one and 1-octen-3-ol (with modified frequencies (MF%) of 82% and 69%, respectively), while in the case of T. melanosporum both had modified frequencies of less than 30%. Ethyl isobutyrate, ethyl 2-methylbutyrate and isopropyl acetate were also significantly higher, while DMS and DMDS had low MF (30-40%) compared to T. melanosporum (>70%). The volatile profiles of both species were also studied by means of headspace solid-phase microextraction (HS-SPME-GC-MS). This showed that the family of C8 compounds (3-octanone, octanal, 1-octen-3-one, 3-octanol and 1-octen-3-ol) is present in T. indicum at much higher levels. The presence of 1-octen-3-ol was higher by a factor of about 100, while 1-octen-3-one was detected in T. indicum only (there was no chromatographic signal in T. melanosporum). As well as showing the greatest chromatographic differences, these two compounds were also the most powerful from the aromatic viewpoint in the T. indicum olfactometry. Therefore, either of the two chromatographic methods (GC-O or HS-SPME-GC-MS), together or separately, could be used as a screening technique to distinguish between T. indicum and T. melanosporum and thus avoid possible fraud.

Does the host tree exert any influence on the aromatic composition of the black truffle (Tuber melanosporum)?

“…The method used for this analysis is described elsewhere and is based on a methodology designed and developed earlier, but with some changes, as for example the mass of truffle analyzed. Approximately 2 grams of sample was placed in a 20 mL SPME vial equipped with a screw cap and a silicon/polytetrafluoroethylene (PTFE) septum (Sigma Aldrich, Steinheim, Germany).…”

Mushrooms and Truffles: Historical Biofactories for Complementary Medicine in Africa and in the Middle East

“…Truffle species have a wide range of host plant species, require a calcareous soil, and have different geographical distribution [67, 68]. They have been found through Europe [69], especially in Italy, France, and Spain and throughout China [70], Australia [71], North Africa and sub-Saharan countries [72, 73], and the Middle East [14, 74]. …”

Chemical Composition and Antioxidant Activity of Tuber indicum from Different Geographical Regions of China

“…In China, there are more than sixty species of Tuber, but only T. indicum can be exported as a major commercial truffle because of its high production and established distribution channels, not to mention its close similarity to the renowned European truffle species T. melanosporum, which shares its morphological and phylogenetic relationships and volatile organic compound (VOC) composition. [9,[30][31][32] T. indicum is mainly distributed in southwestern China (i. e. Yunnan and Sichuan province), and has been found in northeastern and northern China as investigations show. [33] Large quantities of T. indicum from the wild are exported from China, and unethical, unscientific collection practices are rapidly leading to the endangerment of the endemic species in China.…”