Impact of different vinification techniques on the formation of reductive notes in Vitis vinifera cv. Vernatsch

¹ Laimburg Research Centre for Agriculture and Forestry, Laimburg 6 – Pfatten (Vadena), 39040 Auer (Ora), BZ, Italy
² Hochschule Geisenheim University, von Lade Strasse 1, 65366 Geisenheim, Germany

Abstract

The grape variety Vernatsch is prone to the formation of severe reductive notes during alcoholic fermentation (AF), spoiling the fruity aroma characteristic for this variety. We investigated the impact of eight different vinification treatments on the formation of volatile sulfur compounds (VSCs) and their impact on the sensorial quality of the wines in this susceptible grape variety. Without the addition of sulfur under the form of potassium metabisulfite (K₂S₂O₅) to the crushed grapes, wines were significant less reductive. The clarification treatment showed promising results for the diminution of reductive notes, but might not be a feasible strategy for commercial wineries. Changing fermentation temperature, adding air, bentonite or copper to fermenting wines increased the appearance of reductive notes. The addition sulfur prior AF increased reductive notes in Vernatsch wines and needs to be considered as a crucial factor for the formation of reductive notes.