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Red wine quality, composition studied at WSU

Research can help winemakers create good products regardless of circumstances beyond their control.

November 22, 2022

3 Min Read
Washington vineyard
Washington State Wine Commission

As a student in Germany, Ingrid Weilack was inspired by Washington State University enology professor Jim Harbertson. Now, the visiting scholar is experiencing what it’s like to work with him at the Ste. Michelle Wine Estates WSU Wine Science Center.

“I’m excited to be working with Jim,” said Weilack, a PhD student who comes to WSU from the University of Bonn. “I’ve learned a lot since I’ve been here.”

During her three months at WSU, Weilack is continuing her research on the quality and polyphenolic composition of red wines. Polyphenols such as tannins are essential to red wine quality, giving wine its color, astringency, and mouthfeel. Their presence depends on factors including grape ripeness as well as winemaking technology and techniques, and they have intrigued Weilack for some time.

“I’ve always been interested in chemistry and secondary plant metabolites like polyphenols, and how this can be applied to food and drink,” said Weilack, who holds a master’s degree in food chemistry and is pursuing a PhD in the same field. She hopes to defend her dissertation next year.

In Germany, Weilack studied how extreme weather conditions in the country affect grape harvests. There, she examined how different wine technologies, such as increased alcohol levels, can compensate for the polyphenolic immaturity caused by a weather-induced early harvest. Her goal is to discover how different technologies affect astringency, polyphenolic extractability, and the tannins present in grapes harvested early in the season.

This research can help winemakers create good products regardless of circumstances beyond their control.

“If a winemaker has to harvest early, we can advise them on how to modulate the polyphenols and achieve a particular wine style,” Weilack said. “Their wines can still turn out regardless of less-than-ideal conditions.”

Collaboration with Fresno State

Her visit is part of a collaboration between WSU and Fresno State University, where Weilack spent three months prior to coming to Washington. She studied grape-growing techniques that work in Fresno’s hot climate, with the hope of replicating these techniques in Germany’s increasingly warmer temperatures. To aid in her polyphenolic composition research at WSU, Weilack brought pomace and wine samples from her Fresno State trials.

A desire to study abroad and experience life in the U.S. brought her to WSU and Fresno State.

“A lot has surprised me about living here,” Weilack said. “Everybody in the U.S. is so friendly and welcoming! I was expecting that, but it’s a lot different than Germany, where we’re often more reserved.”

She is also enjoying the range of cultural backgrounds at WSU.

“Our working group is international and also has students from throughout the U.S.,” said Weilack. “I enjoy experiencing different cultural perspectives and learning about other students’ projects and having them show an interest in mine.”

The WSU visit is a product of Weilack and Harbertson’s shared research interests and Harbertson’s ongoing collaboration with a group of German wine science researchers. Weilack and her supervisor in Germany previously co-authored a paper with Harbertson.

Different skillsets

“Ingrid has a lot of different skillsets in terms of analysis, and her phenolic research is something I’m also very interested in,” said Harbertson, who typically hosts a visiting scholar every few years. “Most visiting scholar collaborations happen organically. It’s all connected, and most of it is built by friendships between individuals in the industry.”

The pair share a specific interest in exploring tannin extraction in wine and how tannins interact with the various macromolecules found in grapes. Part of Harbertson and Weilack’s collaboration includes studying the forces that govern the amount of color and tannins in wine.

Looking ahead, Harbertson hopes that he and Weilack can publish the findings of their research and that Weilack’s visit will help WSU’s Department of Viticulture and Enology foster relationships with wine science researchers in the U.S. and globally.

“I value the relationship between WSU and researchers in Fresno and Germany,” said Harbertson. “When we work with colleagues in other countries and share research ideas and culture with them, those new viewpoints often reframe how we’re thinking. I hope that, culturally, we can achieve an exchange of ideas. We’re doing that thus far.”

Source: Washington State University

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