Quantitative gas chromatography–olfactometry and chemical quantitative study of the aroma of four Madeira wines

The aroma profile of four Madeira wines from the most emblematic grape varieties, Malvazia, Boal, Verdelho and Sercial, has been studied by sensory analysis, quantitative gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectrometry (GC–MS). The aroma of the wines was characterized as candy, nutty, maderized, toasty, lacquer and dried fruit. The GC–O was carried out on extracts obtained by a dynamic headspace technique. The GC–O profiles of Madeira wines were compared to the GC–O profiles obtained from three young white monovarietal wines made with the same varieties so that the identification of odorants related to the particular process of elaboration of Madeira wines was possible. The aroma profile of Madeira wines was extremely complex, and was rich in sotolon, phenylacetaldehyde, wood extractable aromas, and lacked of the most important varietal aromas, such as linalool, 3-mercaptohexyl acetate and methoxypyrazines. A large number of potentially important and unknown odorants, most of them specific to Madeira wines, was also detected by GC–O. The GC–MS results confirmed most of the results of the GC–O study, which suggests that the proposed GC–O strategy is a useful tool for screening the presence of active odorants in wine.