Caracterização geoquímica dos terroirs vitivinícolas do Rio Grande do Sul

Abstract

This study presents the first integrated geochemical, isotopic, and phenolic dataset for the four main winegrowing terroirs of Rio Grande do Sul—Campanha Gaúcha, Campos de Cima da Serra, Serra Gaúcha, and Serra do Sudeste—providing a robust scientific basis for verifying geographic origin and protecting Brazil’s wine heritage through a multi-proxy approach. A total of nine rock, 27 soil, leaf, and grape samples, and 18 wine samples were collected from seven wineries for organic and inorganic geochemical analyses. Among phenolic compounds, the strongest correlations between leaves, grapes, and wines were observed for resveratrol, vanillic acid, and caffeic acid, while total phenolics, catechin, chlorogenic acid, p-coumaric acid, and resveratrol exhibited the most significant correlations between grapes and wines. Trace element concentrations were generally lower in grapes than in leaves, except for Rb and B. Elevated concentrations of some heavy metals (e.g., Ba, Cu, Zn) were detected in leaves and grapes, exceeding soil reference values, and some grape and wine samples showed Zn and Pb levels above regulatory limits. One-way ANOVA and Tukey’s HSD tests confirmed that Sr isotope ratios (⁸⁷Sr/⁸⁶Sr) differ significantly among terroirs (p < 0.05), whereas ²⁰⁷Pb/²⁰⁴Pb ratios showed limited discriminatory power. PCA integrating isotopic, elemental, and phenolic data enabled clear differentiation of leaves, grapes, and wines among all terroirs, including Vale dos Vinhedos DO wines within Serra Gaúcha. These results demonstrate the effectiveness of multi-proxy geochemical tools, including ANOVA, for terroir authentication and the development of robust Designation of Origin systems for Brazilian wines.