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.
Chemical and climate measures that relate to regional sensory differences
As previously reported, detailed sensory and chemical examination of a large number of commercially produced wines from six regions (Barossa Valley, McLaren Vale, Heathcote, Yarra Valley, Canberra District and the Hunter Valley) was completed. This work involved characterising wines from each region from a sensory point of view, selecting representative examples and then quantifying their sensory attributes as a set. The sensory data were statistically related to almost 70 targeted compositional measures. The models generated were able to predict most key attributes well.
In conjunction with NWGIC researchers, this project showed there were distinctive region-specific sensory differences among wines sourced from six major Australian Shiraz-producing regions. Chemical compounds that related to key region-specific sensory attributes were identified. These compounds can be used as targets for future trials assessing viticultural, winemaking or detailed spatial effects on region-specific Shiraz flavour. In addition, links to climate indices for the wines were demonstrated, with rainfall variables, growing degree days, relative humidity minima and harvest date all being moderately well related to ‘ripe’ flavour attributes as opposed to ‘green’ flavour attributes. However, the amount of variability of the chemical measures explained by the climate data was relatively low, with only 18% variance explained, indicating other region-specific aspects also have a strong influence. With sensory profiles established, and with chemical compounds determined that contribute to the sensory differences between regions, producers can use this information to endeavour to sustain or increase regionally distinct characters.