Effect of picking date and several viticultural techniques on the rotundone concentration of Duras wines

Abstract

Rotundone is a very potent aromatic compound, identified for the first time in 2008, in Shiraz wines by an Australian research team. There are still few very studies on this impact molecule, responsible for heavy peppery notes in wines. Recently it was detected in Duras red wines, a red variety grown in the South West of France. Like several other varietal aroma compounds, its accumulation in the berries could be affected by viticultural and environmental factors. Between 2011 and 2012, IFV Sud-Ouest, in collaboration with the Australian Wine Research Institute, carried out an experiment to determine the incidence of 5 picking dates and 4 viticultural techniques (leaf removal, grape thinning, irrigation, exogenous jasmonic acid spraying) on the rotundone level of red wines from Duras (AOP Gaillac). This compound was analysed in wines elaborated under micro-vinifications techniques (1L Erlenmeyer) in 3 replicates per treatment. Results show that the dynamic of accumulation of this compound is dependent on the vintage conditions and that higher concentrations in wines were reached from half-veraison +44 days. Exogenous jasmonic acid spraying and grape thinning didn’t show any significant impact on the rotundone concentration of the experimental wines. Leaf removal strongly reduced the rotundone concentration in wines which lead to think that its synthesis is impacted by the level of lighting and/or the surface temperature of the grapes. On the other side, wines from the irrigated treatment showed higher levels of rotundone.