For the first time, the distribution of the ‘pepper’ compound rotundone has been mapped in a Shiraz vineyard. Results recently published in the Australian Journal of Grape and Wine Research highlighted a surprisingly wide concentration range of rotundone in grapes across the block. The study showed clearly the large spatial variability of the compound and that it is linked to differences in soil characteristics and topography. The topographical variation pointed towards temperature and/or solar radiation effects being involved, rather than vine vigour.

The rotundone level was measured in grape berry samples from 177 vines within a 6.1 ha block in the Grampians, a region known for producing wines of ‘peppery’ character. The results were mapped and overlaid with other map layers showing variation in soils, topography and vine vigour.

This is believed to be the first study of within-vineyard spatial variability of a key grape-derived flavour compound. It highlights the potential opportunity to use selective harvesting or targeted viticultural manipulation as a means of influencing wine style – in this case the ‘pepperiness’ of Shiraz. The study was conducted with Dr Rob Bramley of CSIRO Ecosystem Sciences and the late Nathan Scarlett of Rathbone Wine Group.

Read the article published on Australian Journal of Grape and Wine Research :
Scarlett, N.J., Bramley, R.G.V., Siebert, T.E. “Within-vineyard variation in the ‘pepper’ compound rotundone is spatially structured and related to variation in the land underlying the vineyard” DOI: 10.1111/ajgw.12075: 9 p.; 2014.