GCxGC-TOFMS in metabolomics of grape and wine samples

Fondazione Edmund Mach (FEM) is a leading institute in grape and wine research. Within the Department of Food Quality and Nutrition a metabolomics platform has been established during the last years. It offers a large variety of analytical instruments (liquid chromatography-tandem mass spectrometry (LC-MS/MS), and gas chromatography-MS/MS) which provide the possibility to measure a broad range of substance classes in many kinds of matrices with both unit resolution MS and also high resolution MS. Recently, the platform was completed with a LECO GCxGC-TOFMS. This talk presents different projects running on this instrument concerning grape and wine samples. The first example deals with Pinot grapes. A comparison of the volatile fraction of a somatic Pinot mutant with the wildtype was done. Volatiles were extracted and enriched with solid phase microextraction (SPME). The GCxGC-TOFMS chromatogram showed around 800 peaks with a S/N > 500 compared to 250 peaks in 1D GC. By applying the statistical compare function of the ChromaTOF software we could find around 50 compounds which were significantly different between mutant and wildtype. We could identify 15 of these compounds by means of authentic standards. The second example deals with the characterization of volatiles of several wines produced from new crossings. In this work the aim was to identify as many substances as possible in the wines, first by comparing mass spectra with an in-house mass spectra library and second by comparing with a commercial library and retention time indices. In parallel the samples were measured with a GC-olfactory to investigate the flavour impact of the volatile metabolites. In the third example the volatile fraction of Lambrusco sparkling wines was used to investigate its capability to serve as marker for the grape varieties used in the wine production. In parallel, the samples were also measured with 1D GC-high resolution MS in CI mode to support the identification of unknown metabolites. This work was partially supported by the AGER, Agroalimentare e Ricerca, cooperative project between grant-making foundations under the section “wine growing and producing”: project New analytical methodologies for varietal and geographical traceability of oenological products; contract n. 2011-0285.