Odour composition of the summer truffle, Tuber aestivum

Geographical traceability of Italian white truffle (Tuber magnatum Pico) by the analysis of volatile organic compounds

Results are presented that were obtained on the geographic traceability of the white truffle Tuber magnatum Pico. Solid-phase microextraction coupled to gas chromatography/mass spectrometry (SPME-GC/MS) was employed to characterize the volatile profile of T. magnatum white truffle produced in seven geographical areas of Italy. The main components of the volatile fraction were identified using SPME-GC/MS. Significant differences in the proportion of volatile constituents from truffles of different geographical areas were detected. The results suggest that, besides genetic factors, environmental conditions influence the formation of volatile organic compounds. The mass spectra of the volatile fraction of the samples were used as fingerprints to characterize the geographical origin. Next, stepwise factorial discriminant analysis afforded a limited number of characteristic fragment ions that allowed a geographical classification of the truffles studied.

Evaluation of morphology, cytology and mycorrhizal relationships of desert truffles (Terfezia boudieri) in Iran

Wild edible fungi are collected for food and to earn money in more than 80 countries. In one of these countries, Iran, several species of edible truffle can be found growing in Bandar-e Abbas, Tabriz, Qazvin and Zanjan provinces. They are normally harvested during mid-winter and early spring, particularly from January to March. Experinced harvesters identify the location of the truffles from crevices that appear in the surface of the soil above the truffles. A yellowish species grows solitary in the soil, is about the size of a large potato and has affirm texture. This species forms 5-10 cm below the soil surface and is yellowish inside. The truffles that had been collected from these areas were investigated in laboratories. Cytological evaluations showed that each ascus contains 8 ascospores. According to morphologic and cytological characteristics, this species was identified Terfezia boudieri. This species is not ectomycorrhizal with trees. Because the vegetation in the area consists of moss, lichen and perennial sedges. The field and laboratory studies showed that Kobresia bellardii have ectomycorrhizal associations with Terfezia boudieri in studied areas.

Solid-phase microextraction gas chromatography/mass spectrometry: a new method for species identification of truffles

This study describes a rapid method to identify different truffle species by analysis of their volatile compound fraction using static headspace solid-phase microextraction gas chromatography/mass spectrometry. The volatile organic compounds (VOCs) were extracted using a new 2-cm 50/30 microm DVB/CAR/PDMS fiber placed for 10 min in the headspace of the truffle sample with the vial maintained at 20 degrees C (in a thermostatically controlled analysis room). The mass spectra of the VOC chromatograms were represented as 'fingerprints' of the analysed samples. Next, stepwise factorial discriminant analysis afforded a limited number of characteristic fragment ions that allowed a classification of the truffle species studied. This new method provides an effective approach to rapid quality control and identification of truffle species by analysis of their volatile fraction. Moreover, this method offers the advantage of minimizing thermal, mechanical, and chemical modifications of the truffles, thereby reducing the risk of analytical artifacts.

Truffle aroma characterization by headspace solid-phase microextraction

In the present study, a headspace solid-phase microextraction (HS-SPME) combined to gas chromatography-mass spectrometry (GC-MS) has been used to fully characterize aroma of truffles of different species. A fiber of medium polarity (for flavors) was used to avoid discrimination towards very non-polar and polar volatile compounds. In a previous work, extraction conditions were optimized by means of an experimental design leading to the following conditions that were used in the present study: extraction temperature, 53 degrees C; extraction time, 13.6 min; and equilibrium time, 5 min. A comparison among different truffles species has been established in terms of qualitative and quantitative differences on volatile composition. By using the optimal extraction conditions and GC-MS it was possible to identify 89 compounds in two different truffle species such as Tuber aestivum and Tuber melanosporum. An attempt has been made in order to be able to determine the influence of different geographical origins on the aroma fraction of such fungi.

Truffle aroma analysis by headspace solid phase microextraction

An experimental design has been used to optimize the extraction of volatile compounds from summer truffle aroma (Tuber aestivum) by using headspace solid phase microextraction. The extracted compounds have been analyzed by gas chromatography with a flame ionization detector and by gas chromatography-mass spectrometry (GC-MS). In an attempt to develop an objective method to fully characterize truffle aroma, a fiber of medium polarity (for flavors) was used to avoid discrimination toward very nonpolar and polar volatile compounds. To optimize the extraction conditions, a response surface experimental design was applied considering three factors such as extraction temperature, equilibrium time, and extraction time. From the statistical analysis of the experimental design, it was possible to determine that the most important factor influencing the abundance of aroma compounds was the extraction temperature. Optimal extraction temperature was established at approximately 50 degrees C. By using GC-MS, it was possible to identify 37 compounds, most of them previously described as responsible for truffle aroma.