Establishment of the varietal volatile profile of musts from white Vitis vinifera L. varieties

Musts from four white Vitis vinifera L. varieties of Bairrada Appellation (Fernao-Pires, Bical, Cerceal and Arinto) were analysed over two harvests (1998 and 1999). The free volatile components were extracted using a liquid-liquid continuous method and were analysed by gas chromatography/mass spectrometry. The potential volatile compounds (PVC) were determined after a heat treatment followed by an enzymatic treatment. The PVC fraction contained the compounds released by the enzymes from the glycosidically linked components plus the compounds produced by the heat treatment at the must pH (3.2) as well as compounds arising from the thermal degradation of sugars. Based on three varietal chemical groups, namely terpenoids, C-13 norisoprenoids and aromatic alcohols, the volatile profile of each of the four varieties was established, which allowed their aroma potential to be defined. Fernao-Pires exhibited a profile significantly different from those of the other varieties, with a higher number and concentration of volatile compounds. As a consequence of the fact that the four varieties exhibit different volatile composition patterns (different components and different distributions between free and PVC forms), winemaking technologies should be specifically developed for each variety for the improvement of wine aroma quality. Owing to the complexity of the data, including the harvest effect, a contrast data pre-treatment was applied before the utilisation of principal component analysis. The results suggest that it is possible to establish markers (volatiles) for the characterisation of must varieties independently of the harvest effect. (c) 2007 Society of Chemical Industry.