LINKING TERROIR AND THE VOLATILE COMPOSITION OF OKANAGAN VALLEY CHARDONNAY WINES

The relative concentrations of 71 identified organic volatiles in 12 Okanagan Chardonnay wines from the 2000 vintage have been determined using gas chromatography - mass spectrometry to explore relationships between processing methods, location of grape production and volatile composition. Wines come from two wineries (Quails Gate=4 wines; Mission Hill=8) whereas grapes used in the wines originated from three geographically and climatologically distinct areas in the north (Kelowna, cooler and damper=3 wines), central (Naramatta=5) and southern Okanagan (Osoyoos, hotter and dryer=4). A matrix of compound versus compound Pearson correlation coefficients calculated from Z-scored data (to put all compounds on the same scale) was examined using linear multidimensional scaling (MDS) in two dimensions and reveals a tendency for the fermentation acids, esters and alcohols to plot separately. Inverting the Z-scored matrix and comparing samples using MDS and Pearson correlation coefficients shows that the dominant factor controlling the organic volatiles is the winery that produced the wines. This suggests that processing factors such as fermentation organisms and conditions or the use of barrels (used only in Quails Gate wines) have a dominant effect on wine organic chemistry. However, discriminant analysis shows that wines can be separated according to geographic origin using a number of combinations of esters with as few as 4 compounds. Previous work has shown links between the trace element composition of Okanagan wines and the origin of grapes but a relationship between trace elements and wine quality is unestablished. These new experiments support the idea that factors contributing to terroir (geographically controlled soil composition and climate etc.) have a measurable impact on wine volatile composition providing a closer link between the aromatic and palate appeal of wines and place of grape origin.