Danielle Fox, Christopher Beaver, Annette Loring, Elizabeth Tomasino, and James Harbertson*
*Washington State University, 2710 Crimson Way, Richland, WA, 99354-1671 (jfharbertson@wsu.edu)

Sauvignon blanc grapes were harvested at three potential alcohols (11, 13, and 15% v/v, ABV) from a vineyard in Paterson, Washington, in 2018 and 2019. Alcohol was controlled for prefermentation by either adding water or sugar. For each harvest, the 13 and 15% ABV wines were dealcoholized to 11 and 13% ABV using a small-scale dealcoholization (DA) unit. The initial experimental alcohol was treated as the control, the dealcoholized wine as the treatment, and the wine sharing the same alcohol target and harvest date as the dealcoholized wine was designated as the negative control. Basic analysis of main wine components was performed and untargeted solid phase micro-extraction gas chromatography-mass spectrometry (SPME-GC-MS) was used to identify major aroma compounds. Targeted analysis was performed on various classes of wine aromatics (alcohols, esters, aldehydes, thiols) informed by the untargeted analysis. Descriptive analysis of the 2019 wines was performed by 12 panelists (five male, seven female). Harvest and pre- and postfermentation adjustments had the expected changes in alcohol concentration. Titratable acidity significantly increased by ~0.2 g/L tartaric acid equivalents as a result of DA in all cases. All aromatic classes measured were found to increase as a result of higher ethanol and decline as a result of DA, so as to match their negative controls. There were some exceptions, such as thiols, which were more strongly influenced by harvest than by either alcohol adjustment. A principal component analysis of the sensory data showed that DA altered aromatic descriptors significantly. For the first-harvest wines, the DA wines overlapped with their corresponding negative controls, shifting the aroma descriptors from melon and sour candy found in the control to sweaty. For the second- and third-harvest wines, similar trends were found, but they weren’t always significant.

Funding Support: Washington State University, Auction of Washington Wines and all Washington State wine grape growers and wineries through the Washington State Wine Commission.