Viticulture Zonation and Geographical Traceability of Superior Quality Wines through Geochemical Analysis: First Results from a case study in the Cesanese Wine Production Zone

research aiming at the definition of the capability of a territory to wine production, as well as the geographical traceability of typical wines (monocultivar). The main focus is to define an integrated geological-chemical methodology for the characterization of the product, the definition of links between wine composition (and its organoleptic characteristics) and the nature of its substratum, with the aim of valorization of autochthonous vines and the correspondent wines on the grounds of their original environment. The study area includes two DOC and one DOCG areas, located in the Cesanese wine production zone, in the Frosinone and Rome provinces. The research is being conducted considering the geological, morphological, soil and climate characteristics in wine production aptitude. As for wine zonation, a GIS was used for the implementation of a data base and the realization of thematic layers (lithology, altitude, slope, exposition). First results show that in the study area outcrop mostly volcanic formations (33%) and sandstones (28%); vineyards are more widespread on soils deriving from volcanites and in a lesser percentage on sandy and alluvial soils. The study vine sites are mostly located on SE, S and SW slopes, secondarily on W and E slopes, pending between 0 and 10%; additionally 92% of vineyard stands at altitudes ranging between 200 and 400 m a.s.l. Temperature, precipitation and humidity data of the study area have been compared to the references for vine-growing and show that the area is climatically suitable for wine production; moreover bio-climate indices are comprised in the typical range for the production of superior quality wine or high alcoholic grade. In order to verify the geographical traceability of wines, the earth-alkaline metal strontium (Sr) has been considered, and specifically the 87Sr/86Sr isotopic ratio, whose value depends on the Rb and Sr content of the substratum rock and on the time elapsed since its formation. For the isotopic analysis we have selected red wines coming from diverse substratum, and from different wine-making farms, chosen on the grounds of wine quality, the reliability of wine provenance from well defined areas, on the mono variety of the cultivar and the wine making process. For each farm, one or more small area with "Cesanese comune" or "Cesanese di Affile" vines variety, on a homogeneous substratum, were selected; the latter is the most widespread in the study area and is one the few varieties in Latium able to produce superior quality wines. For each vineyard we sampled the rock substratum, soil, grapes, must (with or without yeast) and wine. First results show that the 87Sr/86Sr isotopic ratio of the examined must and wines (also of different years) of each farm does not change and that a good correspondence exists between values of different wines and musts when vineyard are placed on soils originated from the same volcanic substratum. On the contrary, there is no correspondence between these values and those of wines and musts coming from farms whose vineyards are placed on substratum of different origin and age. In order to confirm these results samples of musts of 2010 and wine of 2009 are being analyzed, to confirm the repeatability of results in different climate and atmospheric conditions.