Characterisation of volatile organic compounds in truffles

Namen magistrskega dela je bil ugotoviti ali iz rezultatov določevanja hlapnih organskih spojin (HOS) liofiliziranih tartufov lahko razlikujemo med posameznimi vrstami tartufov in geografskim izvorom ter ali postopek sočasne liofilizacije večjega števila vzorcev v liofilizatorju vpliva na aromatski profil HOS posameznega vzorca. V naključno izbranih vzorcih tartufov (54) različnih vrst (Tuber aestivum, Tuber brumale, Tuber magnatum in Tuber melanosporum) smo določevali HOS po razviti metodi mikroekstrakcije na trdnem nosilcu iz plinaste faze nad vzorcem (HS-SPME) s plinsko kromatografijo sklopljeno z masno spektrometrijo (GC-MS). Ugotovili smo, da se aromatski profil HOS svežih tartufov po liofilizaciji zelo spremeni. Pri razlikovanju vrst tartufov smo z linearno diskriminantno analizo (LDA) določili vrednost navzkrižne validacije za sveže in liofilizirane tartufe > 80 %, kar kaže na to, da posamezne vrste lahko razlikujemo glede na aromatski profil HOS. Po liofilizaciji smo lahko ločevali vse preučevane vrste (T. aestivum, T. brumale, T. magnatum in T. melanosporum). Navzkrižna validacija pri razlikovanju geografskega porekla svežih tartufov je bila 30 %, medtem ko pri liofiliziranih 41 %. Kljub nizki vrednosti, rezultati kažejo, da bi bilo razlikovanje porekla glede na aromatski profil HOS možno. Sočasna liofilizacija večjega števila vzorcev v liofilizatorju vpliva na aromatski profil HOS tartufov.The aim of this theses was to evaluate whether the species and the geographical origin of freeze-dried truffles could be differentiated according to their aromatic profiles based on volatile organic compounds (VOCs), and whether the simultaneous freeze-drying of large number of samples in a lyophilizer affects the aromatic profile of each sample. VOCs were evaluated on randomly selected truffle samples (54) of different species (Tuber aestivum, Tuber brumale, Tuber magnatum and Tuber melanosporum) using a combination of headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled with mass spectrometry (GC-MS). The results demonstrate that the aroma of freeze-dried truffles of all species investigated was deeply modified as compared to the fresh truffles. The cross-validation, which was determined with linear discriminant analysis (LDA) of fresh and freeze-dried truffles used in the differentiation of species was > 80%, which indicates that individual species can be distinguished according to their aromatic profile. After freeze-drying, we were able to distinguish all the species tested (T. aestivum, T. brumale, T. magnatum and T. melanosporum). Cross-validation of distinguishing the geographical origin of fresh truffles amounted to 30%, while that of freeze-dried 41%. Despite the low cross-validation score, the results indicates possible differentiatiojn between geographical origin based on aromatic profile. The analysis confirmed that the simultaneous freeze drying of a large number of samples in the lyophilizer influences changes in the aromatic profile of truffles