Metabolic Profiling of Grape and Wine Aromas
The complex aroma of wine is derived from many sources, with grape-derived components being responsible for the varietal character. The ability to monitor grape aroma compounds would allow for better understanding of how vineyard practices and winemaking processes influence the final volatile composition of the wine. We have developed a procedure using GC-MS combined with solid-phase microextraction SPME) for profiling the free volatile compounds in Cabernet Sauvignon grapes. Different sample preparation (SPME fiber type, extraction time, extraction temperature and dilution solvent) and GC-MS conditions were evaluated to optimize the method. For the final method, grape skins were homogenized with water and 8 mL of sample were placed in a 20 mL headspace vial with addition of NaCl; a polydimethylsiloxane (PDMS) SPME fiber was used for extraction at 40° C for 30 minutes with continuous stirring. Using this method, twenty-seven flavor compounds were monitored and used to profile the free volatile components in Cabernet Sauvignon grapes at different maturity levels. Ten compounds from the grapes, including 2-phenylethanol and Î²-damascenone, were also identified in the corresponding wines. Using this procedure it is possible to follow selected volatiles through the winemaking process.