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

Cabernet Sauvignon grapes were harvested at three potential alcohols (11, 13.5, and 16% v/v, ABV) from a vineyard in Sunnyside, WA in 2018 and 2019. Alcohol was controlled for prefermentation by either dilution or chaptalization at each harvest. Basic wine chemistry was performed as well as 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, terpenes, and pyrazines) based on untargeted analysis. Descriptive analysis was performed on 2019 wines by nine panelists (four males). Ortho- and retro-nasal attributes were more significantly affected by ethanol than by harvest: seven ortho-nasal and eight retro-nasal attributes compared to one ortho-nasal and retro-nasal, respectively. Green bell pepper was significantly higher in the early-harvest and low-alcohol treatments, while dark fruit was higher in the late-harvest and high-alcohol treatments. Harvest affected astringency and bitterness, while alcohol affected all taste and mouthfeel attributes. Bitterness and astringency were highest in the late-harvest wines and sourness was highest in the low-alcohol wines. Principal component analysis of sensory data explained 89.5% of the data (75% on the x-axis) driven by alcohol. SPME-GC-MS showed that esters, alcohols, and aldehydes were significantly more abundant in higher-alcohol wines, while methoxypyrazines were lower in the early-harvest and higher-alcohol wines. Overall, the SPME-GC-MS results support the sensory data. Our results reinforce the growing multitude of data that shows that alcohol, rather than harvest date, controls flavor and aroma in wine.

Funding Support: Washington Wine Commission