Environmental influence on grape phenolic and aromatic compounds in a Nebbiolo selection (Vitis vinifera L.)

Nebbiolo (Vitis vinifera L.) is one of the most important wine red cultivar of North-west Italy. A better understanding of the complex relations among grape aromatic and phenolic maturity and environmental factors may strongly contribute to the improvement of the quality of Nebbiolo wines.

In order to investigate this matter, a trial was set comparing the agronomic behavior and grape composition, with particular regards to aromatic and phenolic compounds, of a Nebbiolo clonal selection (CVT 63) when grown in two locations environmentally different of Piedmont Region (North-west Italy): La Morra and Lessona, areas of production of the renowned “Barolo” and “Lessona” VQPRD wines respectively. These locations differ in terms of climate, soil texture, row exposition and sloping.

Agronomic performances of clone CVT 63, assessed over three growing seasons, differed very much depending on the environment, while grape composition (soluble solids, total flavonoids and total anthocyanins) resulted comparable between the two locations. The environmental imprint, however, was clearly present on some grape qualitative aspects such as the anthocyanin profile and the dotation in aromatic substances. Despite the similar amount of grape total anthocyanins assessed in the two sites, the grapes produced in Lessona, showed a profile characterized by an higher % of peonidin-3-glucoside (di-substituted anthocyanin) and a lower % of malvidin, petunidin and delfinidin-3-glucoside (tri-substituted anthocyanins).

The modifications in the profile due to different environments may have strong implications on the evolution of wine color, being peonidin-3-glucoside less stable to degradation during fermentation and wine ageing. In terms of aromatic substances, the grapes produced in La Morra resulted richer in benzenoids, terpenes and norisoprenoids, and this bound aroma dotation may give an important contribution to the intensity and complexity of wine bouquet. Our results confirmed the environmental impact on grape qualitative composition and the consequent potential imprinting of the “terroir” on the characteristics of Nebbiolo wines.