Regionality in Australian Pinot Noir wines: A study using NMR and ICP-MS with commercial wines

Aim: Wine quality and character are defined in part by the terroir in which the grapes are grown. Metabolomic techniques, such as nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS), are used to characterise wines and to detect wine fraud in other countries but have not been extensively trialled in Australia. This study aimed to investigate the use of ICP-MS and NMR to characterise a selection of Pinot noir wines.

Methods and Results: Duplicate bottles of commercial Pinot noir wines from seven viticultural regions (six in Australian and one in New Zealand) were collected during 2013/4, either as donations from the wineries or via commercial sources. These regions represented a range of viticultural climates and vintages (2010-2013). These wines were analysed using NMR and ICP-MS by the Institut Heidger (Osann-Monzel, Germany) using their proprietary methods. Multivariate data analysis was then undertaken, trialling principal component analysis (PCA), multifactorial analysis, and analysis of coinertia. Interestingly, the results showed that the wines from varying terroirscould be best distinguished using PCA of their mineral content, and this statistical separation of the wines was clearest by geological region. Metabolomic analysis of the wines using NMR did not reveal any correlations with climate in terms of daytime temperatures. NMR metabolites did not prove useful for distinguishing wines by region, but interestingly there was a better separation based on Australian states, presumably reflecting the marked differences in climates. An analysis of coinertia suggested that the two datasets were not redundant.

Conclusions: 

ICP-MS appears to have promise in determining regionality in Australian and New Zealand wines, perhaps reflecting the extremes in geology often found in these two nations. Although the regional characteristics relating to contributions by terroir were frequently overwhelmed by strong local mineral contributions to the wines – possibly resulting from varying soil types, previous mining activity, and viticultural methods such as irrigation – these differences showed promise in providing distinctive ‘fingerprints’ for individual wines. NMR may also be useful for analysing and refining metabolite composition during winemaking and viticulture.

Significance and Impact of the Study: This was the first such study in Australia using both NMR and ICP-MS. The study provided valuable data for future ‘fingerprinting’ commercially bottled wines, as a precaution against wine ‘forgery.’