Headspace Solid-Phase Microextraction Analysis of Volatile Organic Sulfur Compounds in Black and White Truffle Aroma

Abstract

Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-ion trap mass spectrometry (GC-ITMS) has been shown to be a powerful technique for detection of volatile organic sulfur compounds (sulfur VOCs) in aromas of white truffles (Tuber magnatum Pico) and black Perigord truffles (Tuber melanosporum). For both species all of the compounds previously identified during several studies were detected in single analyses, and in the case of white truffles three new sulfur compounds were identified : dimethyl di- and trisulfide and 1,2,4-trithiolane. Comparison with traditional headspace Tenax adsorption/desorption GC-MS analyses of the aromas showed that the HS-SPME technique is less suited for quantitative analyses, especially because the polydimethylsiloxane fiber coating used in the SPME device strongly discriminates more polar and very volatile compounds. With the Tenax adsorption analysis two new sulfur compounds were identified in black truffle aroma : 1-(methylthio)propane and 1-(methylthio)-1-propene. The predominant sulfur compounds are dimethyl sulfide and bis(methylthio)methane in white truffle aroma and dimethyl sulfide in black truffle aroma. On evaporation of the sulfur compounds from cuttings of black truffle a distinct mushroom odor appeared that is ascribed to the considerable contents of 1-octen-3-ol and other C 8 compounds, characteristic for mushroom aroma, that are present in the black truffle aroma.