Exploring the regional typicality of Australian Shiraz wines using untargeted metabolomics

Abstract

Background and Aims Shiraz is the most widely planted winegrape cultivar in Australia. Sensory studies have indicated that different grapegrowing regions in Australia produce distinct styles of Shiraz wines that differ in flavour characteristics. The current project aimed to characterise the underlying volatile composition associated with regional Shiraz wine styles. Methods and Results Wines were selected from six geographically distinct regions and the volatile compounds were analysed using gas chromatography time-of-flight mass spectrometry to provide a comprehensive and holistic overview of the wine volatilome. A suite of R language based software enabled feature extraction and importance ranking, following an untargeted metabolomics approach. A classification model based on the random forests algorithm using the 80 most important compounds correctly associated all samples to regions. A range of these compounds, including terpenoids, benzenoids, esters, furan derivatives and aliphatic alcohols, has been associated with grape composition, winemaking influences and the ageing process. Conclusions The results suggest that the regional compositional differences in varietal wines may be influenced by all processes in the entire wine production chain. Significance of the Study The current study highlighted the chemical basis underlying the regional typicality of Australian Shiraz wines, and identified specific volatile compounds that may be associated with a region.