James Harbertson,* Danielle Fox, Christopher Beaver, Annette Loring, and Elizabeth Tomasino
*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. Basic analysis of main wine components was performed. Wine samples were analyzed first using untargeted solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) to identify major aroma compounds present. Targeted analysis was performed on various classes of wine aromatics (alcohols, esters, aldehydes, and thiols) informed by the untargeted analysis. Descriptive analysis was performed on the 2019 wines by 12 panelists (five male, seven female). There were significantly more esters and isoamyl alcohol in the first harvest and 15% ABV treatments. Thiols and one of the corresponding esters and alcohols were found to depend significantly on harvest and alcohol, with 3-mercaptohexyl acetate, hexyl acetate, and cis-3-hexen-1-ol having the highest concentration in the first harvest wine. 3-Mercaptohexanol was found to be significantly affected by alcohol and was highest in the last harvest, 15% ABV wine. There was significantly less methionol in the last harvest wine. A two-way analysis of variance of the sensory attributes found that tropical, citrus, melon, sour candy, sweaty, and overall aromatic intensity were significantly greater in the first harvest wines. For the first harvest wines, sweet and hot taste attributes were significantly greater while sour was significantly less. Herbal/mint, briny, earthy, floral/grassy, and boxwood were significantly greater in the second harvest wines. Increased alcohol concentration significantly increased stone fruit, oxidized, alcohol, and overall aromatic intensity aroma attributes and hot, viscous, bitter, and sweet taste attributes. Both harvest and alcohol impacted the aroma and taste attributes of the wines. Notably, alcohol alone is effective at altering aromatic and taste attributes and wine volatile aromatic concentrations independent of harvest.

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