Caracterização dos vinhos Merlot e Cabernet Sauvignon da serra gaúcha através de determinação das razões isotópicas 13C/12C e 18O/16O

Abstract

In this work, wines provided by micro-winemakings of the variety Merlot and Cabernet Sauvignon of the sub-regions of Pinto Bandeira, Vale dos Vinhedos, Nova Pádua and Monte Belo do Sul in the 2005 and 2006 harvest have been studied. It has been established the isotopic ratios 13C/12C of the ethanol and 18O/16O of the water and ethanol, seeking for a possible differentiation among the varieties and production harvests, and a possible relation between the place of origin and its geographic features (altitude and latitude) and climatological conditions (temperature, precipitation and humidity). It has been used a isotope ratio mass spectrometer (IRMS) coupled to an elementar analyzer for the analysis of the 13C/12C of the ethanol and 18O/16O of the water and to a gas chromatograph for the analysis of 18O/16O of the ethanol. In relation to the values of δ13C, it is observed that the differentiation among the sampling sub-regions are less selective and do not follow the same statistical order found for the analysis of δ18O, however, the analysis of δ13C of the ethanol may be used to differentiate sub-regions that are not differentiated statistically by the analysis of δ18O. The value behaviors of δ18O of the water and the ethanol follow the same statistical order of differentiation. Regardless of the grape variety used in this work, it has been possible to differentiate the sub-regions through the isotopic analysis of the δ18O, in both production harvests, except for the Vale dos Vinhedos and Monte Belo do Sul, 2005 harvest, which did not present statistical differences. The latitudes of the different sub-regions presented statistical differences and demonstrated an influence mainly in the values of δ18O of the water. The analysis of δ18O of the water and the ethanol of the wine conveyed to be more selective and efficient in the discrimination of the cultivation sub-regions than the analysis of δ13C of the ethanol. It has been observed a strong correlation between the values of δ18O of the water and the ethanol. The altitude and latitude influence mainly the values of δ18O of the water and the ethanol. The climate influences are more noteworthy in distinguishing the production harvests than the cultivation sub-regions.