FLAVONOID POTENTIAL OF MINORITY RED GRAPE VARIETIES

Abstract

The alteration in the rainfall pattern and the increase in the temperatures associated to global climate change are already affecting wine production in many viticultural regions all around the world (1). In fact, grapes are nowadays ripening earlier from a technological point of view than in the past, but they are not necessarily mature from a phenolic point of view. Consequently, the wines made from these grapes can be unbalanced or show high alcohol content. Dramatic shifts in viticultural areas are currently being projected for the future (2). However, these wine-growing areas have the potentiality to stay in place if they shift from the “international” varieties to autochthonous varieties, usually better adapted to the local climate of the growing area (3). In the Spanish “Castilla y León” region, an important number of minority Vitis vinifera L varieties have been identified and conserved in a germplasm bank. It is therefore interesting to study their potential to make quality wines. For this purpose, the present study aimed at determining by HPLC-DAD-MSn (4) and HPLC-MS-MRM (5) the anthocyanin, flavonol and flavanol composition of some of them (Mandón de Zamadueñas, Mandón de Arribes, Gajo Arroba, Tinto Jeromo, Bruñal, Merenzao, Estaladiña and Cenicienta) coming from different parts of Castilla y León.

Quantitative differences were observed in the total anthocyanin contents and in the proportions of individual pigments. Malvidin derivatives prevailed over the rest of the anthocyanins in all cases, but in Merenzao and Estaladiña grapes, the proportion of the latter ones were greater than in the other varieties. Varieties also differed in the p-coumaroyl/acetyl derivatives ratio and in the proportion of caffeoyl derivatives. Flavonol total content and profile also changed among varieties, with myricetin and quercetin derivatives being the most abundant ones. Flavanol profile, which has been reported to be less useful for chemotaxonomic purposes than anthocyanin and flavonol profiles, was also different even for varieties coming from the same part of the Castilla y León region, highlighting again the existence of varietal differences in flavonoid composition. The knowledge of the flavonoid composition of these red grape minority varieties will be helpful for enologists to adapt the winemaking process to exploit the potential of each variety and to obtain quality wines from the natural resources of the region.