Finish Your Wine – WSU Researchers Explore White Wine Finish

Food science, said Emily Goodstein, was “the perfect marriage” between two things she really loves: food and science. “Few people know that food science exists, but it impacts everybody, every day.”

Goodstein currently works as a beverage product developer in Seattle where, she said, she makes “tasty stuff.” Before she started her career in the product development field, though, she earned a master’s degree in food science at Washington State University.

“I was teaching a sensory evaluation class which Emily was in, and she got interested in time intensity — how long a sensation lingers on the palate,” said Carolyn Ross, an associate professor of food science at WSU and a leading sensory analysis expert. Ross drew an analogy between the time intensity of wine with that of chewing gum: the longer you chew, the less flavor you perceive in the gum. Although much more complex, wine is similar in that its flavor changes and diminishes over the time it is in your mouth.

    Emily Goodstein and a glass of her research subject, white wine. Photo courtesy Emily Goodstein. Click image to download higher-resolution version.
Emily Goodstein and a glass of her research subject, white wine. Photo courtesy Emily Goodstein. Click image to download higher-resolution version.

Time intensity studies are an integral part of a branch of food science called sensory analysis. Sensory analysis combines experimental design with statistical analysis to evaluate consumer products. Many large companies employ sensory analysts to help guide decisions about product development, merchandising, and marketing.

The time intensity question that interested Goodstein is one commonly referenced on bottles of Chardonnay with a phrase claiming, for instance, that the wine inside has a “long, oaky finish.” How, she and Ross wondered, could they unpack that phrase in order to test it scientifically and also to get an idea of what it means to consumers? In other words, how long is long and what are consumers willing to pay for wines with a long finish?

Freshly harvested white grapes. Photo: Washington State University.
Freshly harvested white grapes. Photo: Washington State University.

What they did was design a series of experiments that would involve panelists of human assessors tasting various types of wine. The experimenters trained a group of tasters to recognize certain flavors – fruity, floral, oak, mushroom – and then trained them to use a computer interface that would let the assessors record their perception of each wine they tasted.

“Anecdotally, we know that people say fruity and floral flavors finish early and that mushroom and oaky flavors finish later,” said Ross. “We wanted to test that in an empirical way.”

Goodstein and Ross used model wines to reduce the complexity of flavors that the tasters had to assess. A model wine starts with super pure water with ethanol added to bring it up to the alcohol level of wine, a few other compounds to mimic the acidity of wine, and the flavor compound researchers want to investigate. The oaky flavor of chardonnay, for instance, is from a naturally occurring compound called lactone, which is found in oak trees as well as many other plants.

“Regular wines are very complex, full of acids, sugars and a lot of flavor compounds” Goodstein said. “We simplify things in order to target a particular flavor in our testing.”

Goodstein and Ross were able to confirm the anecdotal assumption about white wine finish: fruity flavor does fade first, while mushroom and oak flavors lasted longer.

What surprised the researchers was that a separate panel of consumers who hadn’t been trained to differentiate between the four target flavors could also distinguish the difference in finish time. Ross and Goodstein equipped the consumer panelists with timers and asked them to mark the point at which they could no longer perceive the oak flavor. “Sometimes the sophistication of consumers’ palates is underestimated,” said Ross.

Goodstein added that, in terms of willingness to pay, tasters didn’t care for the oaky finish of what most winemakers would consider a mark of a high-end bottle. The oak finish of more expensive wines is due to barrel aging. Even though barrel aging is expensive, consumers in this study indicated a taste-based preference for wines that cost less.

“Chardonnays are being marketing with a clearer indication of oak levels,” Ross said, “which will help consumers chose their preferred style of wine.”

Goodstein concurred, adding, “If a winemaker is trying to produce a wine with a broad appeal, then barrel aging might not be the way to go, while a more sophisticated consumer might indeed go for that.”

Brian Clark

This article was originally published in Voice of the Vine, a monthly e-newsletter on viticulture and enology research at Washington State University.

Washington State University food scientists and students are actively engaged in product development and testing, and many other aspects of food-related work, the nation’s largest occupational sector. Learn more at the School of Food Science website.

Learn more about the science of sensory evaluation at the WSU Sensory Lab website.