Exploring Interactions Between Vineyard Performance, Grape and Wine Composition and Subregional Boundaries—The Terroir of Barossa Shiraz

Abstract

Background and Aims: Viticulturists and winemakers have a considerable interest in understanding the influence of climate, soil, viticultural and winemaking practices on wine sensory outcomes—that is, understanding the terroir concept, which is important for regionality and claims of product distinctiveness. In this investigation, an empirical study of grape and wine composition, including sensory evaluations, was used to inform the delineation of subregional areas of the Barossa Zone geographical indicator (GI).

Methods and Results: A spatiotemporal investigation of Shiraz was undertaken with vineyard zones selected to exemplify maximum heterogeneity within a site. Objective measures of vine performance and grape and wine composition were clustered using the k-means approach, and up to three clusters of vineyard sites were evident within the dataset. Clusters were associated with vineyard elevation and thus growing temperatures. The most important measures of composition defining each cluster were the volatiles ethyl octanoate, diethyl succinate, 1,8-cineole and 3-methyl butyl acetate in grapes. Sensory attribute intensity differences were apparent for wines from some subregions, and projection of the important attributes for clusters defined in this study to key sensory differences shows a high variance in composition related to sensory features from year to year. The spatial outcomes of clusters for vineyard sites align with of some outcomes of prior clustering approaches using data-rich sources for precision agriculture.

Conclusions: Subregional zones within the Barossa can be identified where sufficient variations between vineyard elevations exist that impart grape compositional differences, which in turn translate into wine sensory attributes.

Significance of the Study: This empirical study provides some evidence for regionality within the Barossa with up to three subregions identified in some vintages.