Determining the impact of thiophenols on ashy flavor recognition in smoke-affected wines

Abstract

Wildfires are an increasing concern for wine-producing regions worldwide, as they generate smoke containing volatile organic compounds that can be transported over long distances and can be absorbed by wine grapes [1]. Wines produced with smoke-impacted grapes are found to have uncharacteristic smoky, burnt, and dirty flavors, with an ashy aftertaste being a particularly distinctive and negative attribute [2].

While volatile phenols are well-documented contributors to smoke-related flavors in wine, recent research suggests that thiophenols play a key role in the perception of ashy off-flavors [3]. The objective of this study was to determine the concentration at which thiophenols induce the perceptual “ashy” attribute in different styles of Pinot noir and Cabernet sauvignon wines. Using an adaptive staircase procedure, ashy flavor recognition thresholds for total thiophenols were assessed in wines containing varying levels of smoke-related volatile phenols (45 µg/L, 135 µg/L, 450 µg/L). Psychometric curves were fitted to estimate threshold distributions across individuals to be able to determine risk levels of a consumer perceiving a wine as ashy.

Results indicated that an inverse relationship was found between phenol and thiophenol concentration to produce a perceptual ashy flavor. This is important to be understood by the wine industry, as volatile phenols can be introduced to a wine during other parts of the winemaking process. Additionally, differences in recognition between styles were evident at the lowest phenol concentration, but at higher phenol concentrations, threshold variability decreased. This allows for better guidance of interpretation of chemical markers for potential sensory descriptors. These findings provide critical insight for winemakers and industry stakeholders, enabling informed decision-making regarding smoke-affected vintages. Beyond threshold determination, this study underscores the broad range of individual sensitivities to smoke-related compounds, highlighting the importance of consumer perception in mitigating economic losses due to wildfire events. Understanding these sensory impacts will help guide strategies to reduce waste and optimize wine quality in the face of increasing wildfire challenges.

References

[1] Jiang, W., Parker, M., Hayasaka, Y., Simos, C., & Herderich, M. (2021). Molecules, 26(11).

[2] Parker, M., Osidacz, P., Baldock, G. A., Hayasaka, Y., Black, C. A., Pardon, K. H., Jeffery, D. W., Geue, J. P., Herderich, M. J., & Francis, I. L. (2012). J. Agric. Food Chem., 60(10), 2629–2637.

[3] Tomasino, E., Cerrato, D. C., Aragon, M., Fryer, J., Garcia, L., Ashmore, P. L., & Collins, T. S. (2023). Food Chemistry Advances, 2.