A 2-year multisite study of viticultural and environmental factors affecting rotundone concentration in Duras red wine

Abstract

Aim: A study was carried out in 2013 and 2014 to determine the key environmental and viticultural variables affecting the concentration of rotundone, the black pepper aroma compound, in Vitis vinifera L. cv. Duras red wines at 10 different vineyard blocks.Methods and Results: For each block, data for fruit quality attributes, as well as climatic and agronomical variables, were collected. Rotundone was quantified in wines prepared by microvinification techniques (in a 1-L Erlenmeyer flask). Rotundone concentration varied across blocks from 63 ng/L to 239 ng/L in 2013 and from 25 ng/L to 115 ng/L in 2014. Three separate partial least squares regression models were constructed to predict rotundone concentration in wines in 2013, in 2014, and in both vintages. Gluconic acid, a secondary metabolite of Botrytis cinerea, had a substantial contribution to the 2013 and multivintage models, with a negative regression coefficient with rotundone concentration. Other predictors were associated with abiotic factors such as cumulative rainfall, thermal index, hours of sunshine and mean daily irradiation.Conclusions: Our results indicate that mesoscale climatic variables are the key factors determining rotundone concentration, and also suggest that Botrytis cinerea may be involved in rotundone degradation.Significance and impact of the study: Our findings may assist grape growers producing Duras red wines to select specific vineyard blocks with the aim of producing wines with a desired rotundone concentration. They also open up new fields of investigation into mechanisms involved in possible rotundone degradation by Botrytis cinerea.

Recent advancements in understanding the terroir effect on aromas in grapes and wines

“…The effect of light on (-)-rotundone has not been formally investigated but there is evidence suggesting a stimulating effect. Indeed, mean irradiation, hours of sunshine and cumulative solar exposure (CSEv) over the maturation showed a positive contribution to prediction models for (-)-rotundone concentrations in wine (Geffroy et al, 2019a;Harner et al, 2019). These observations are in accordance with studies showing that defoliation can enhance (-)-rotundone when implemented in cool-climate vineyards, where the increasing effect on berry surface temperature is limited (Homich et al, 2017, Geffroy et al, 2019b.…”

“…Aroma expression in grapes and wines is positively related to radiation. High radiation reduces green flavours (methoxypyrzaines and C6 compounds; Koch et al, 2012) and increases fruity flavours induced by monoterpenes (Friedel et al, 2016), volatile thiols, esters (Šuklje et al, 2014), C 13 -norisoprenoids (Marais et al, 1999) and peppery notes from (-)-rotundone (Geffroy et al, 2019a, Geffroy et al, 2019b.…”

Grape Berry Secondary Metabolites and Their Modulation by Abiotic Factors in a Climate Change Scenario–A Review

“…Sesquiterpenes contribute little to grape and wine aroma, as their concentrations are often below the olfactory threshold. The most studied sesquiterpene is (-)-rotundone, which confers a peppery character to some red and white cultivars, such as Syrah, Duras, Durif, and Viognier (Wood et al, 2008;Geffroy et al, 2014Geffroy et al, , 2018Geffroy et al, , 2019.…”

The Actual and Potential Aroma of Winemaking Grapes

“…Rotundone is a sesquiterpene that is also present in grapes and can give a peppery aroma to grapes and wines [128]. In certain varieties, like Shiraz or Duras, and under favorable agronomical conditions [129,130], rotundone can accumulate in the berry exocarp in levels in the order of 600 ng/kg [128]. The synthesis pathway of rotundone in grape is not clear, but α-guaiene has been proposed as a potential precursor [131].…”