Research done by scientists at WSU suggests that a wine’s alcohol concentration may play a larger role than other properties of the wine in determining its taste, aroma and mouthfeel.

Jim Harbertson, an associate professor of enology, said the study involved producing wines of different alcohol concentrations and comparing them to wines made from grapes of varied maturity. The wines were blind-taste-tested by a panel of trained tasters for a descriptive analysis of their flavors and properties.

He said this study provides a basis to help winemakers understand how alcohol concentration affects the flavor, aroma and mouthfeel of their wine.

“We wanted to understand what elements are present that are really affecting things,” Harbertson said.

He said alcohol has a lot of chemical effects that influence the sensory perception of wine more than flavor alone. Alcohol can affect the viscosity and body of wine. It can inhibit a nerve response, causing a hot or burning feeling. It can also have aromatic effects. 

Harbertson said wine producers typically look to use the maturity of their grapes to determine the quality and characteristics of their wine.

“Every year people spend tons of money and time sending people out to vineyards to take samples to evaluate maturity,” Harbertson said.

Using samples to evaluate the maturity of grapes can be difficult and inaccurate, he said, as each plant on the vineyard ripens at different rates.

“This problem is universal,” Harbertson said. “Everyone who makes wine in the world has the same problem.”

Kay Simon, a wine producer at Chinook Wines and collaborator on this study, said soluble solids like sugars increase in grapes as they mature, and this subsequently affects the ethanol content of the wine, so deciding when to harvest grapes is important for wine style and quality.

Harbertson said this study will help wine producers understand what characteristics their wine will assume if they harvest their grapes earlier or later in the season.

“They can … start making more informed decisions about what they are doing,” he said.