Olivia Jefferies,* Thomas S. Collins, and Elizabeth Tomasino
*Oregon State University, 1428 NW Highland Drive, Corvallis , OR, 97330 (olivia.jefferies@oregonstate.edu)

The wine industry is continuously threatened by the presence of wildfire smoke. Grapes exposed to smoke in the vineyard result in an ashy flavor in the finished wine. This flavor negatively affects wine quality, and in many cases, smoke-affected grapes are not made into wine. This can result in significant economic losses for the wine industry. Smoke-related compounds, thiophenols and volatile phenols, in combination cause the ashy flavor associated with grape smoke exposure. The formation of varietal thiols, important aroma compounds in Sauvignon blanc, has been researched extensively. An increase in sulfur-containing nutrients increases production of varietal thiols in Sauvignon blanc. We investigated whether adding sulfur-containing nutrients increases the concentration of smoke-related thiophenols during fermentation. In this study, smoke-exposed Pinot noir grapes from Oregon were made into wine using microferments. Different nutrient additions were added prior to yeast inoculation. Treatments included glutathione, glutastar, and diammonium phosphate (DAP). There were two controls: smoke-affected grapes with no nutrient additions and non-smoke-affected grapes with no nutrient additions. Free phenols were analyzed using GC-MS/MS; phenol-glycosides and thiols were analyzed using LC-MS/MS. The nutrient additions had no effect on the fermentation process, as all wines went through fermentation successfully. Results from this project are significant as they will provide another technique for winemakers to alleviate the effects of smoke exposure through varying nutrient additions during fermentation. Altering nutrients is an easy and inexpensive way for winemakers to manage this environmental issue.

Funding Support: USDA-ARS