Identifying Sub-Regional Differences in Marlborough Sauvignon Blanc Wine with a Customised FOSS WineScanTM Calibration

Abstract

The primary aim of the research was to fully profile 12 Marlborough Sauvignon blanc wines via chemical and sensory analyses. A second aim was to develop a custom calibration for the FOSS WineScan that collected near infrared spectra, and which can potentially be used to identify wines according to its subregion of origin. The aroma chemical profile using GC–MS methods was obtained, along with the output according to Descriptive Analysis using a trained sensory panel for six Constellation sub-regional wines as well as six commercial blends. As expected, the concentrations for the varietal thiols, which contribute tropical and passionfruit notes, were well above perception thresholds, with the exception of 3-mercaptohexanol acetate (3MHA) for two of the wines that were older than the others. The analytical data showed a decrease in 3-isobutyl-2- methoxypyrazine concentration, with a capsicum aroma, compared to previous surveys of Marlborough wines taken 5–10 years ago. The concentrations were above perception threshold for several fruity ester compounds quantified within the wines, with the exception of the same two older wines that were low in the varietal thiols. The analytical data obtained via GC–MS was used to investigate the correlation between sensory descriptors and the corresponding aroma compound concentrations for each of the wines. The sensory panel results indicated strong contribution of the varietal thiol 3MHA to the associated “sweaty/passionfruit” descriptor, for all of the sub-regional wines and most of the commercially blended wines. The wines also exhibited further fruity and floral notes. The wine from the Awatere sub-region exhibited stronger “green” characters than fruity/floral aromas. A slight variation could be seen between various sub-regions. However, no definitive results could be justified as only a single vintage (2015) was used for the sub-regional wines. The calibration build was successful from the data obtained for the FOSS WineScan. Further data, including near infrared spectra for the aroma compounds, needs to be collected and entered into the method before it is fully functional and ready to use in the commercial laboratory.