Defining regional variability and uniqueness of premium Australian Shiraz
This project is part of a collaborative study with Charles Sturt University and the National Wine and Grape Industry Centre. It will define sensory attributes of wines sourced from multiple regions that contribute to distinctive regional character and will provide objective quality markers for both grapes and wine for future use in vineyard and winery assessment. This project will investigate carefully selected commercially produced wines from premium regions and study the variation in the wines’ sensory properties. Wines of specific criteria will be selected using rapid sensory methods with expert winemaker panels, to characterise the wines from each region and reduce the number of samples to a manageable number for further detailed sensory analysis.
The sensory attributes of the wines from each region will be quantified using sensory descriptive analysis. The associations of the sensory attributes with the concentrations of wine flavour compounds will be determined. The study will allow definition of chemical and sensory attributes which separate wines from the regions, and provide the basis for further investigations into the causes of these differences.
Sensory profiles of Shiraz wines that relate to regional and sub-regional differences
Commercially produced premium Shiraz wines, mainly sourced from single vineyards, were selected from the Barossa Valley, McLaren Vale, Heathcote, Yarra Valley, Canberra District and the Hunter Valley, and winemakers from each region assessed the wines from that region using the Pivot© Profile sensory assessment method. More than 70 winemakers were involved. This method allows a two-dimensional map to be produced showing the similarities and differences among the wines, overlaid with sensory descriptors used by the tasters.
For each of the regions studied, there were marked differences among the wines, with cluster analysis allowing groups of wines within each region with similar sensory properties to be identified. Descriptors such as ‘mint’, ‘herbal’, ‘jammy’, ‘dark fruit’, ‘red fruit’, ‘spice’/‘pepper’, ‘oak’, ‘concentration’/ ‘weight’ and ‘tannin’ separated the wines. Some regions had distinctive descriptors applied, although, as expected, there was a degree of commonality.
Wines from each region were then selected based on statistical criteria, to allow characterisation of representative wines from all the regions. A set of 22 wines that represented the sensory differences of wines from the six regions was then characterised by the AWRI’s sensory descriptive analysis panel, to provide a detailed profile of each wine, with the intensity of defined attributes rated in replicate by the judges. There was good separation of the wines on the basis of region. There were important differences among the wines in ‘mint’, ‘stalky’ and ‘pepper’ attributes, with ‘dried fruit’ and colour descriptors also differing greatly. The sensory data will be related to chemical compositional results. A Pivot© Profile assessment was also completed on these wines using a separate panel of technically trained AWRI staff, which provides further information on the reliability and validity of this rapid method.
The study will allow definition of attributes that separate wines from the regions, allow the compounds driving the regional sensory differences to be identified and provide the basis for further investigations of the causes of these differences.
Sensory assessments by wine trade members
Sets of ultra-premium Australian Shiraz wines, selected on the basis of displaying regionally distinct sensory properties, were assessed by groups of wine trade participants at events held by Wine Australia in New York and Hong Kong. This allowed further evaluation of the Pivot© Profile method and examination of sensory differences among Australian Shiraz wines, benchmarked against international styles. The results from these tastings will be related to those provided by a group of international sommeliers and Australian winemakers earlier in the project.