In this study, researchers wanted to gain more insight into the ‘terroir effect’ of different regions on Shiraz wines. They wanted to determine what chemical compounds were responsible for certain sensory characteristics. In addition, they wanted to ascertain whether the climate of a specific site was related to the key chemical compounds found in wines from that site. This could link certain sensory attributes to specific regions.
Project layout
- 22 Commercially produced Shiraz wines from two different vintages and six different regions in Australia were selected for the study. The wines were selected through rigorous preliminary sensory evaluation to pick out wines that represent the range of sensory attributes unique to each region;
- A range of climate metrics from 20 years of data were analysed for each region;
- Phenological data was modelled for each site and each year;
- 70 Basic chemical composition measures, volatile compounds and colour/tannin were analysed for each wine;
- Wines were profiled using quantitative sensory descriptive analysis.
Results
- Chemical analysis indicated that 18 of the 70 measures were significantly different between regions;
- Wines with higher monoterpene levels were associated with floral aromas;
- Later budburst and time of harvest contributed to wines with stalky or cooked vegetal aromas due to a higher concentration of cinnamate esters and dimethylsulfide;
- Sites with higher radiation values were correlated to higher tannin, colour density, norisoprenoid compounds and phenylethyl acetate – leading to more intense dark fruit/dried fruit and tannin/colour traits;
- Wines from sites with higher rainfall figures had lower compositional measures and were generally rated to have less sensory characteristics.
Significance of the study
Overall, wines could be well grouped based on their origin and unique chemical fingerprints exist for all the regions in the study. The climate of each region could be strongly linked to key chemical compounds that are responsible for the distinctive sensory attributes of wines from each region. Results from this study can help producers to better understand how their regional climate affects the characteristics of their wines. It can also aid in site selection when planting vineyards with a specific wine style in mind.
Reference
Pearson W., Schmidtke L.M., Francis I.L., Li S., Hall A., Blackman J.W. Regionality in Australian Shiraz: compositional and climate measures that relate to key sensory attributes. Australian Journal of Grape and Wine Research 27, p 1-14, 2021. https://doi.org/10.1111/ajgw.12499
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