Ignacio Arias-Pérez, Wen Yan, and Anita Oberholster*
*University of California Davis, 595 Hilgard Lane, Davis, CA, 95616 (aoberholster@ucdavis.edu)

The increasing incidence of wildfires in winegrape-producing regions of the West Coast of the United States has highlighted the need to develop mitigation strategies to manage the impact of smoke exposure on grapes and the resulting wines. There are now several products and processes available to mitigate smoke in the vineyard and treat smoke-impacted wine. Therefore, it is important to investigate different potential ways to manage the impact of grape smoke exposure, especially as it seems unlikely that a single tool will solve this problem. The objective of this experiment was to compare the relative efficacy of applying different potential protective barrier sprays to grapes in a simulated wildfire scenario. Four Cabernet Sauvignon vines were exposed to smoke in Robert Mondavi Institute vineyards at UC Davis. Three bunches from each vine were treated with different products to compare the effects of applied materials in reducing absorption of smoke marker compounds (13 different treatments were applied). Individual clusters were submerged in the potential barrier spray for 30 sec. The vines were exposed to smoke three days after treatment for two hours. Control samples were taken prior to smoke exposure (buffer samples) and smoked control grapes were sampled at different times after exposure. All treated bunches were harvested a week after smoke exposure. Grapes were analyzed for free and total volatile phenols using the acid hydrolysis methodology (GC-MS) and for gly­cosylated volatile phenols (UHPLC-qTOF MS). Results from untreated grapes indicate that glycosylation of the free volatile phenols takes place within hours. Additionally, kaolin consistently lowered the amount of volatile phenols absorbed during smoke exposure under these conditions.

Funding Support: USDA-AR