Chemical and sensory diversity of regional Cabernet-Sauvignon wines

Abstract

AIM: To investigate chemical and sensory drivers of regional typicity of Cabernet Sauvignon from different geographical regions of Australia.

METHODS: Commercial Cabernet wines (n = 52) from Coonawarra, Margaret River, and Yarra Valley Geographical Indications of Australia, and from Bordeaux, France, were selected for extensive chemical and sensory analysis.1 A range of analytical methods were optimised to quantify a comprehensive array of volatile compounds (> 70) originating from different sources, including grape, fermentation, oak maturation, and ageing. Along with basic chemical data, measurement of non-volatile compounds such as tannins and other secondary metabolites and elements was also undertaken. Multivariate statistical analysis using partial least squares regression was applied to the combined chemical data and the sensory analysis ratings obtained through a trained descriptive analysis panel of the same wines, to determine important compounds driving relevant sensory attributes.

RESULTS: The compound 1,4-cineole, described as ‘mint’ and ‘bay leaf’, was partly responsible for separation of the Cabernet Sauvignon wines from the Australian regions, particularly from Margaret River, whereas compounds such as 4-ethylphenol and 4-ethylguaiacol were linked to the aromas of ‘earthy’ and ‘yeasty’, which drove some of the separation of Bordeaux wines from the others. Varietal thiol, 3-mercapto-1-hexanol, which is mainly associated with Sauvignon Blanc and other white wine varieties, was measured in concentrations above its aroma detection threshold in all of the wines analysed, with similar concentrations present in Bordeaux and Coonawarra wines, and significantly higher concentrations in Margaret River and Yarra Valley wines. Additionally, non-volatiles such as particular elements drove some the separation between the regions; for example strontium was present in highest concentration in the Coonawarra wines and was found at lowest concentration in the Bordeaux wines. Free anthocyanins were also found to differ between Coonawarra and Bordeaux regions, with higher concentration being measured in the latter.

CONCLUSION

In determining the influential drivers of sensory properties of regional Cabernet Sauvignon wines, this study has uncovered various volatile and non-volatile constituents that are associated with specific sensory attributes. This is an important step in being able to define and subsequently help preserve the distinctive characters associated with regional Cabernet Sauvignon wines.