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

Smoke taint from recently increased wildfires in the United States has led to unde­sirable sensory characteristics in wine due to smoke compounds absorbed into the grapes and released during fermentation. Edible coatings may be used to entrap or block smoke compounds from entering grapes, preventing smoke taint. This study developed polysaccharide-based coatings to prevent smoke taint in winegrapes. Three coating suspensions consisting of cellulose nanofiber (CNF), β-cyclodextrin (βCD), and/or chitosan (CH) were evaluated at Southern Oregon Research and Exten­sion Center Vineyard on Pinot noir grapes. Coatings were applied at three different times during grape growth: bunch closure, veraison, and both bunch closure and veraison, with uncoated grapes as control. Each coating group and application time contained three to four trellises. Harvested grapes were analyzed for total soluble sol­ids (TSS), pH, titratable acidity (TA), size, weight, and appearance. Half of the grapes in each treatment were washed to remove the coating and the other half were un­washed prior to analysis. Coating suspensions were cast into films to evaluate water vapor permeability (WVP), water solubility, strength, and elongation. Complexation between coating suspensions and guaiacol (model smoke compound) was analyzed by UV-vis spectroscopy scanning (200 to 400 nm). Field study showed that all three coatings did not influence (p > 0.05) size, weight, appearance, TSS, pH, or TA of grapes compared with uncoated control. Washed and unwashed grapes also showed no significant differences for TSS, pH and TA. Water adsorption, solubility, and tensile strength differed for each film. Developed coatings demonstrated capability to pre­vent smoke taint for winegrapes without affecting grape growth physiology. Coatings can be easily removed from grapes as needed. This study provides an effective solu­tion to prevent smoke taint in winegrapes and ensure wine quality..

Funding Support: Oregon Department of Agriculture USDA-ARS