Brandt Bastow, Anita Oberholster,* Ignacio Arias-Perez, Jonathan Cave, William Drayton, Robert Coleman, and Cristina Medina‐Plaza
*University of California, Davis, 595 Hilgard Ln., RMI North, Davis, CA, 95616 (aoberholster@ucdavis.edu)

Winegrowing regions worldwide have seen more wildfires in recent years, costing the industry billions of dollars in lost revenue. During a wildfire event, significant quantities of volatile phenols are released into the air. These compounds are easily absorbed into grapes through the cuticle, where they become glycosylated into mono-, di-, and triglycosides. Wines produced from smoke-impacted grapes can have unfavorable sensory attributes described as smoky, medicinal, band-aid, ashtray, and burnt rubber. During the 2020 wildfires, analytical laboratories were inundated with an unprecedented volume of samples, creating delays of over a month. For this reason, a high-throughput method of analysis which can be easily adopted by commercial and winery laboratories is needed to assess smoke exposure risk. Reducing the number of samples to be analyzed using advanced analytical techniques will save time and money. Simultaneous UV-vis and fluorescence spectroscopy has shown that smoke-tainted wines can exhibit distinct absorbance and fluorescence spectral differences. Building upon this knowledge, a calibration curve will be developed using smoke-impacted wines and serial dilutions with non-smoked exposed control wines. Nine varietals were harvested from several Northern California vineyards in 2022 and used to produce 20 wines. Half of each grape varietal was intentionally smoked in a tent for five hour prior to fermentation in a controlled setting. Wines will be analyzed by both gas chromatography-mass spectrometry and fluorescence spectroscopy. Using multivariate statistical analyses, correlations between the two analysis methods will be developed. Future studies will incorporate sensory analysis to build a smoke taint index.

Funding Support: Specialty Crop Multi-State Program.