1H NMR spectroscopy data to discriminate Petit verdot wines from three different soil types in the São Francisco valley, Brazil

Tropical wines have been produced in the São Francisco river Valley thirty years ago, in the Northeast of Brazil. The main grape cultivar used for red tropical wines is ‘Syrah’, but wines have presented fast evolution, if they were made in the first or second semester, due to the high values of pH in grapes and wines and high climate temperatures. In the region, vine can produce twice a year, because annual average temperature is 26.5°C, with high solar radiation and water from irrigation. Petit Verdot cultivar was used commercially in one winery until 2011, when this one stopped to produce fine wines (Vitis vinifera L.) to produce table wines (Vitis labrusca). This cultivar presents a high powerful to help tropical wines increasing their stability, due to the high acidity, low pH e high phenolic concentration in the grapes and red wines. NMR spectroscopy is a powerful tool allowing in a single analysis to find many analytical compounds in grapes and wines. PCA multivariate statistical analysis applied on NMR data allows to discriminate samples and to identify markers compounds from the variables evaluated.

The aim of this work was to evaluate Petit Verdot wines harvested in three different soils, the first one sandy, the second one gravelly cambisoil and the third one sandy-clayey argisoils, by using 1H NMR spectroscopy data. Vines were planted in 2002 in the winery on six hectars, conducted on traditional lyre, grafted onto 101-14 Mgt and irrigated by drip. Grapes were harvested in January 2014 and wines were elaborated by traditional red winemaking, then analyzed one month after bottling by 1H NMR spectroscopy. It was possible to determine alcohols, organic and amino acids, and phenolics in the Petit Verdot wines. Results showed a significantly difference in terms of metabolic compounds, of the wines evaluated from the three different soils. PCA was able to find markers from each soil type. Results are discussed according to the enological potential of each plot.