Lindsay Garcia, Trung Tran, Jooyeoun Jung, Joseph DeShields, D. Cole Cerrato, Michael Penner, Alexander D. Levin, Yanyun Zhao, and Elizabeth Tomasino*
*Oregon State University, 100 Wiegand Hall, Corvallis, OR, 97331 
(elizabeth.tomasino@oregonstate.edu)

Winegrapes exposed to wildfire smoke can produce wines with burnt and ashy sensory characteristics, resulting in loss of product. Currently, there are no effective solutions in the market to prevent uptake of smoke compounds into grapes. In this study, innovative film coatings were developed to prevent smoke phenols from entering Pinot noir grapes. Four different film types were developed using cellulose nanofibers as the coat-forming matrix. The formulations were developed by incorporating different quantities of chitosan and/or β-cyclodextrin into the matrix. The coatings’ effectiveness in reducing smoke phenols was investigated. Film coatings were applied at veraison in a vineyard in Southern Oregon, where two smoke events occurred during the 2022 vintage. At harvest, half of the grapes were washed to remove the films. This was to determine whether smoke phenols are blocked or bind to the film coatings. Further analysis of the interaction of smoke phenols with film coatings was done by observing any volatile phenol diffusion through the film using a custom-made polytetrafluoroethylene apparatus. Smoke phenols in grape juice were analyzed using gas chromatography-mass spectrometry and smoke glycosides using LCMS. Results show that some of the film coatings were effective at reducing the amount of smoke compounds that absorbed into the grapes.

Funding Support: USDA-SCRI, Oregon Department of Agriculture, USDA-ARS