Enology - Characterization and Mitigation of Smoke Taint in Wine Session

Lik Xian Lim* | Cristina Medina-Plaza | Catherine Routt | Jean-Xavier Guinard | Anita Oberholster

Oak aging Mitigates the Effect of Grape Smoke Exposure on the Sensory Profile of Different Red and White Wine Matrices

Lik Xian Lim,* Cristina Medina-Plaza, Catherine Routt, Jean-Xavier Guinard and Anita Oberholster

3072 Woods Circle, Davis, CA, 95616, lxlim@ucdavis.edu

The wildfires that swept through Napa Valley in 2020 caused an estimated USD$3.7 billion economic loss to the grape and wine industry. During a wildfire event, volatile phenols (VPs) are released in fresh smoke from burning wood (lignin) and are absorbed through the grape berry skin, where they are rapidly glycosylated. The wines made from smoke-impacted grapes are characterized sensorially as medicinal, smoky, and possessing a retro-nasal ashtray character. However, there are matrix differences among varieties and winemaking styles that can affect smoke expression as well as the synergistic effects among VPs. In this study, serial dilutions of non-impacted and impacted (intentionally smoked postharvest) wines were used to create wines with differing levels of smoke impact across varietals (Cabernet Sauvignon, Zinfandel, and Chardonnay). The influence of oak aging on smoke impact mitigation was also studied (12-mo new oak-aged and stainless steel control). Gas chromatography-mass spectrometry and liquid chromatography-triple quadrupole mass spectrometry were used to quantify free and total VPs, and individual bound glycosides, respectively. Descriptive analysis was used to evaluate sensory characteristics of wines. There was a linear relationship between the amount of VPs and glycosides present in a blend and the amount of smoke-impacted wine present. Wines with high VP levels determined by chemical analysis also had higher smoke ratings determined by the descriptive panel. Generally, wines that underwent barrel aging for 12 mo had less “ashy aftertaste” and smoke-related attributes in all three varieties. Stainless steel control wines were more fruity, but also more smoky, across all smoke-related attributes. These findings contribute to our understanding of grape smoke exposure at different levels of taint and the potential use of barrel aging to mitigate overall smoke perception in wine across these taint levels.

Funding Support: USDA Agricultural Research Service, California Department of Food and Agriculture, Jackson Family Wines

Francesco Maioli* | Chen Liang | Arran Rumbaugh | Ron Runnebaum

Effect of Smoke Exposure on Different Varieties of Red Grapes and Related Wines: A Case tudy

Francesco Maioli,* Chen Liang, Arran Rumbaugh and Ron Runnebaum

*UC Davis, Hilgard Lane RMI North, Davis, CA, 95616, fmaioli@ucdavis.edu

In recent years, exposure of vineyards to smoke from wildfire events has been shown to directly affect grape composition and, subsequently, wine quality. Smoke taint has emerged as a significant concern for the global wine industry. In 2020 alone, the United States suffered an estimated $3.7 billion in damages due to wildfires and tainted grapes and wines. The industry needs tools and methods to determine smoke impact in a vineyard after a wildfire. This case study examines the impact of the 2024 Lake Fire in Santa Barbara County on nearby vineyards during the early stages of red grape ripening. The smoke-exposed grape samples and the resulting wines were collected from five different red grape varieties: Cabernet Sauvignon (n = 5), Cabernet franc (n = 1), Merlot (n = 2), Malbec (n = 1), and Pinot noir (n = 1). Grapes were cultivated at varying altitudes but within ~5 km of the fire. Smoke-exposed grapes were fermented and wines were produced according to local winery protocols. The effect of smoke on both the grapes and the wines was assessed by quantifying volatile phenols and their glycosylated forms by GC-MS/MS and LC-MS/MS analysis, respectively. Environmental data, including local air quality measurements and satellite images, were collected to track the movement and concentration of smoke and correlate with grape and wine composition. The study revealed how different red grape cultivars respond to smoke exposure, particularly during early stages of ripening (preveraison). It also demonstrated how this exposure translated into the wines produced and provided insights into how winemaking influences the release of volatile phenols from glycosylated forms.

Funding Support: USDA

Olivia Jefferies | Elizabeth Tomasino*

Advancing Smoke Taint Mitigation: The Potential of Sulfur-Based Nutritional Approaches

Olivia Jefferies and Elizabeth Tomasino*

*Oregon State University, 100 Weigand Hall, Corvallis, OR, 97331, elizabeth.tomasino@oregonstate.edu

Wildfire smoke presents an ever-growing challenge for the wine industry, threatening grape quality and winemaker livelihoods. When grapes in the vineyard are exposed to smoke, the resulting wines often develop an ashy, smoky flavor that compromises sensory quality. The underlying cause of this ashy flavor has been linked to a combination of smoke-related compounds, specifically thiophenols and volatile phenols. While much is already being explored about these compounds and their impact, there is a growing need for practical solutions that can mitigate smoke exposure’s effects during winemaking. Sulfur-containing nutrients, widely recognized for their role in enhancing varietal thiols—key aroma compounds in Sauvignon blanc—may offer a potential avenue for addressing smoke taint in wine. Previous studies demonstrated that increasing sulfur-based nutrients can promote production of thiols, raising the question of whether these same nutrients could influence the formation of smoke-related thiophenols during fermentation. This research aims to explore that possibility by investigating the effect of sulfur-based nutrient additions on the concentration of smoke-derived compounds in wine. Smoke-exposed Pinot noir grapes from Oregon were processed through microfermentations with a variety of nutrient additions: glutathione, Glutastar, and diammonium phosphate (DAP). Two controls were included—one using smoke-impacted grapes without nutrients and another using clean, non-smoke-exposed grapes. Advanced analytical techniques like GC-MS/MS and LC-MS/MS were used to measure free phenols, phenol-glycosides, and thiols. All fermentations proceeded successfully, with no adverse effects from the nutrient treatments, demonstrating that these additions are viable for winemaking processes. While nutrient additions did not appear to directly alter the concentration of smoke-related compounds, this study provides valuable insight into how winemakers might approach the challenge of smoke exposure.

Funding Support: Specialty Crop Research Initiative Grant #2021-51181-35862/project accession #1027470 from the USDA National Institute of Food and Agriculture and USDA-Agricultural Research Service (ARS) project number 2072-21000-057-00D

10:00 am – 10:20 am	Oak Aging Mitigates the Impact of Grape Smoke Exposure on the Sensory Profile of Different Red and White Wine Matrices Lik Xian Lim, University of California, Davis
10:20 am – 10:40 am	Effect of Smoke Exposure on Different Varieties of Red Grapes and Relative Wines: A Case Study Francesco Maioli, University of California, Davis
10:40 am – 11:00 am	Advancing Smoke Taint Mitigation: The Potential of Sulfur-Based Nutritional Approaches Olivia Jefferies, Oregon State University, Corvallis

Enology – Characterization and Mitigation of Smoke Taint in Wine Session

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