Study of volatiles in grapes by dynamic headspace analysis: Application to the differentiation of some Vitis vinifera varieties

Abstract The aim of our study was to determine the varietal aromas (free volatiles) from grapes by the analysis of isolated compounds according to the method proposed by Salinas and co-workers for wine samples. The results were applied to their differentiation. Grapes of the following varieties were studied: Monastrell, Tempranillo, Cabernet Sauvignon, Dyer Grenache (dark-purple), Airen, Chardonnay and Ugni Blanc. To 100 g of crushed grapes was added a fermentation inhibitor (gentamicine) to impede the formation of new aromas. Skins and juice were kept together for 1 h at 10°C. The samples were purged with He for 20 min at a flow of 84 ml/min and the volatiles were adsorbed in a metal tube packet with Tenax TA. The desorption was carried out by thermal desorption in a kit coupled to a gas chromatograph and a mass spectrometer. The application of cluster analysis to the volatiles was differentiated into three groups: one for white grapes, one for Monastrell, Tempranillo and Cabernet Sauvignon, and the other for Dyer Grenache. Hexyl acetate, benzyl alcohol, phenylethyl alcohol and benzaldehyde were the four discriminant variables used in the group differentiation.