Early Oxidation Detection in White Wine by Electronic Tongue: A Preliminary Study

Abstract

In white wines, early detection of oxidation would alert winemakers to monitor potentially troubled wine more closely and take preventative measures to mitigate undesirable browning, flavors, and odors in their products. Current early oxidation detection methods include assessment by browning index, trained sensory panels, and quantification of byproducts such as quinones. The objective of this study was to assess the capability of the e-tongue, a fairly new instrument that has previously been used to detect wine faults caused by spoilage organisms, in detecting early oxidative changes in Chardonnay wine. Clear bottles of Chardonnay were stored partially opened (treatment) in the dark at 2.2°C for 24 weeks. Wines were assessed at seven time intervals (0, 1, 2, 4, 8, 16, and 24 weeks) using the e-tongue and a semi-trained sensory panel with rate-all-that-apply descriptors. Beginning at week 8 of storage, the e-tongue discrimination indices (DI) between control and treated wine (sealed wine stored alongside partially opened wine bottles) were high (DI > 80%) and remained high throughout the study, indicating that the e-tongue distinguished between control and treated samples. However, sensory panelists detected an increase in the intensity of vinegar/nail polish remover aroma attributes, attributes associated with wine oxidation, after 16 weeks of storage. These results suggest that the e-tongue is a useful tool in the early detection of oxidized wine samples as compared to a sensory panel that perceived differences between control and treated wines 8 weeks after differences were detected by the e-tongue.