Evoluzione degli Antociani e dei Flavonoidi durante la Maturazione di Uve Autoctone e Internazionali nell’ambiente della Sicilia Occidentale

In the 2006 vintage was followed the evolution of total anthocyanis and total flavonoids of skins as well as of monomer catechins, dimer procyanidins and total flavonoids of seeds of Nero d’Avola, Syrah, Merlot and Cabernet sauvignon berries, in environments of average hill of western Sicily, warm - arid during the maturation period (from 18 to 21 August the temperatures overcome 40 °C). The situation of stress, caused by the high temperatures registered in the above period, even if negatively influenced the synthesis of the anthocyanis, did not induce important variations in the profiles of these molecules that remained quite invariant especially in Nero d’Avola and Syrah. The consequences of the thermal stresses on the synthesis of the different classes of anthocyanins, were different in the Merlot and in the Cabernet sauvignon. In the Merlot was partially inhibited the synthesis of trisubstituted molecules and the expression of ipotetical p-cumaril transferase, in the Cabernet sauvignon was exalted the synthesis of trisubstituted molecules and partially inhibited the ipotetical acetil transferase. It doesn't seem that the thermal stresses have modified the evolution of catechins, dimer procyanidins and total flavonoids in seeds. The extractability of these flavonols during the maturation appeared, in fact, similar to that found in other environments with notably different climatic characteristics. In all the varieties studied, the amount of the seed undergone to an important decrease after veraison, but during the phase of stress, as well as in proximity of the harvest there were small variations.