Modelling impact of viticultural and environmental factors on rotundone in Duras wine

Abstract

Rotundone is the aroma compound responsible for peppery aroma in red wines which was discovered in 2008 in a Syrah wine from Australia. More recently, it has been found in several cultivars grown in the South West of France such as Duras, Gamay and Malbec.  A study was conducted in 2013 and 2014 to determine the key environmental and viticultural variables affecting the concentration of rotundone in Duras wines from 10 vineyards located in the South West of France. For each plot, more than 40 variables were collected over the vine growing season and winter dormancy. The WaLIS water balance model was used to calculate stem water potentials at different time points. Partial least squares regression (PLSR) was conducted to model rotundone. Rotundone concentrations were higher in the cooler and wetter 2013 growing season. Some high rotundone vineyards in 2013 showed low levels of concentrations in 2014 which led us to think that fixed variables don’t have a large contribution to the rotundone model. For 2013, precocity of veraison, cumulative rainfalls over the veraison-harvest period and gluconic acid had negative regression coefficients to model rotundone. For the 2014 and 2013-2014 models, rotundone was best predicted by cumulative rainfalls during the 1st of April-30th of September and by stem water potentials 15 days before veraison in 2014. Important variables identified for modeling rotundone in wine were those associated with mesoclimate and grape sanitary status.