Screening potential coating materials to reduce the absorption of volatile phenols into grapes during simulated wildfire conditions

Authors: ARIAS-PÉREZ, IGNACIO - University Of La Rioja; WEN, YAN - Desert Research Institute; Rumbaugh, Arran; LIM, LIK XIAN - University Of California, Davis; MEDINA-PLAZA, CRISTINA - University Of California, Davis; OBERHOLSTER, ANITA - University Of California, Davis

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2026
Publication Date: 4/25/2026
Citation: Arias-Pérez, I., Wen, Y., Rumbaugh, A.C., Lim, L., Medina-Plaza, C., Oberholster, A. 2026. Screening potential coating materials to reduce the absorption of volatile phenols into grapes during simulated wildfire conditions. Foods. 15(9). Article 1499. https://doi.org/10.3390/foods15091499.
DOI: https://doi.org/10.3390/foods15091499

Interpretive Summary: Smoke from wildfires emits volatile organic compounds, which can be absorbed by grapevines. Wines made from smoke-exposed grapes can result in "smoke-taint" characterized by smoky and ashy flavors. This is a critical issue for American grape growers, leading to severe economic losses. Currently, effective mitigation or prevention strategies do not exist. This study screened 12 different commercially available materials to determine their effectiveness in reducing the uptake of smoke related compounds by grapes. This study successfully identified several sprays that have potential to reduce smoke marker absorption into grapes, while also identifying several sprays that exacerbate the issue. Future work will use the successful sprays in a vineyard setting.

Technical Abstract: Wildfires release volatile phenolic compounds (VPs) that can be absorbed by grapevines, potentially resulting in “smoke taint” in wines. This has emerged as a prominent issue for the global wine industry due to negative impact on wine quality and subsequent financial losses. Since effective vineyard mitigation strategies remain limited, this study evaluated the efficacy of different materials applied to grapes to reduce the absorption of smoke marker compounds under simulated wildfire conditions. Twelve materials were applied to individual Cabernet Sauvignon clusters close to harvest. Treated vines were exposed to intentional smoke using a purpose-built tent. Grapes from treated vines, as well as smoke-exposed and non-exposed controls, were harvested at commercial maturity. The results showed a strong stratification of VPs within the tent and in the grapes. Glycosylation began within hours of smoke exposure, with significant increases in almost all glycosylated compounds within 4 hours compared to non-smoked controls. Some materials reduced VP uptake relative to untreated controls (kaolin, charcoal, and two commercial coating formulations—GM3E and GMB6), whereas others increased the absorption of smoke-derived compounds (Parka and wipe-out). These findings highlight that those protective treatments may have variable and sometimes counterproductive effects on smoke compound uptake.