(FruitionSciences) - Rotundone is a fruit compound responsible for the peppery aroma in wines.  Because of its low sensory detection threshold (16 ng/L in red wine and 8 ng/L in water), rotundone produces a strong aroma effect in wines like Syrah, Mourvèdre, Durif (ie. Petite syrah) and Duras. Recently, researchers have demonstrated that Syrah grapes cultivated in Japan (Takase et al.) or in Australia (Scarlett et al.; Drew et al.)  accumulate large amounts of rotundone.

Rotundone variation within vineyard has a spatial structure

According to an Australian study led by Bramley and colleagues, within-vineyard variation in the concentration of the ‘pepper compound’ is spatially structured.

This means spatial variations in the land supporting the vineyard (such as soil electrical conductivity, slope, aspect) induce variations in plant development and fruit microclimate, which ultimately affect fruit composition. Interestingly, this spatial variability is stable between seasons, even when seasonal differences in mean rotundone concentration are very large.

Mapping rotundone spatial variability

In order to determine practical ways to map rotundone spatial variability, a study led by Geoffroy and colleagues was carried on a vineyard from the South West of France (cv. Duras). Geoffroy et al. assessed vineyard spatial variability through measurements of trunk circumference; pruning wood weights (Physiocap® and manual weighing); airborne multispectral imagery (NDVI), and yield at harvest.