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Riesling an important focus
Grad student to the rescue with wine study, map
Tuesday, Nov. 23, 2010
By Brian Clark, College of Agricultural, Human and Natural Resource Sciences
Riesling comprises about 16 percent of Washington’s wine grape production, but not that much is known about it - or other wine grapes, for that matter.
"Unlike other areas of science, where we can do a survey of the published literature, winemaking is very much an oral or undocumented and sometimes proprietary body of knowledge," said Thomas Henick-Kling, WSU’s director of viticulture and enology.
“Riesling is a signature wine grape variety for Washington. Winemakers here are producing outstanding wines that are getting worldwide attention," he said.
"Developing a better understanding of the flavors in our Rieslings will help us produce more distinct, high quality wines," he said. "The first step … is to get a handle on the state of knowledge and the basic flavor groups we find in today’s Rieslings."
But who is up to such a challenge? Enter (stage right; drum roll; tights and cape optional) the state's first Vinifera EuroMaster.
Mapping range of flavor, practices
Seattle native Linn Scott recently completed the two-year Vinifera EuroMaster program in France, Germany and WSU. One of his mentors is a colleague of Henick-Kling.
“It was the connection to Thomas that led me to my research project,” Scott said. He was intrigued by the idea of doing research in his home state while completing his degree from a prestigious consortium of European universities.
Henick-Kling proposed that Scott describe and map the range of Riesling flavors produced in Washington. Combining this sensory descriptive analysis with a survey of viticultural and enological practices in the production of Riesling, Henick-Kling suggested, would serve several important purposes.
"(Expanding) our understanding of Riesling farming and winemaking practices seemed like something that would make a contribution,” Scott said.
Temperature/flavor result a surprise
Scott interviewed winemakers and vineyard managers to assess the state of the art and science of Riesling production. He conducted tasting panels of single vineyard Washington Rieslings, both in Washington and in Germany, in order to construct a flavor map.
“What I found was a spectrum of flavors,” he said. “There was a cluster around mineral-citrus flavors and another around the riper, peachy and floral flavors.”
Most winemakers, Scott said, associate those differences to the temperatures in the vineyards. The common wisdom is that warm sites produce fruit that result in wines with riper flavors, while cooler temperatures produce wines with mineral and citrus flavors.
Curiously, this association was not borne out by data from WSU’s AgWeatherNet, which records temperatures at 134 locations around the state, including many grape-growing areas.
Yeast, lees, other influences
Scott said there were any number of other factors that could produce those flavors independent of the number of degree days (or total heat the grapes are exposed to in the course of a growing season) in the vineyard.
“Among other things, the type of yeast used in the vinification process could confound those results,” he said. Indeed, pioneering work by Henick-Kling shows that the strain of yeast employed for fermentation has a significant impact on a wine’s final flavor profile.
“There was another cluster associated with pear flavor,” Scott continued. “This ester-character could be due to yeast strain or wine age. Then there was a fourth cluster of wines that had all been aged on lees (the residual yeast and other particulates that precipitate out during fermentation and aging).
"In retrospect, this tells me there were probably some additional flavor descriptors that it would have been useful to employ. What we need is a longer, more controlled study.”
How do techniques shape wine?
“The way it looks now,” Scott said, “is that winemaking techniques have a big impact on the way the wine turns out. That vinification techniques influence wine is really a no-brainer. But exactly how various techniques and practices shape the wine is still largely unknown.”
“The need for grape growers and winemakers to work hand in hand is clear,” Scott said, echoing the winemaker’s credo that a great bottle of wine begins in the vineyard. “We don’t even really have a clear definition of what we mean by ‘ripeness.’ There are lots of obvious points of control that affect the final product.”
Closing in on terroir
Some of those points touch on the mysterious, semi-mystical notion of “terroir.” More of a belief and a marketing term than anything scientifically demonstrable, Scott said it’s a term that gets used a lot – so much, in fact, that it’s difficult to know what is meant by the word. The growing cadres of wine bloggers are notorious for speaking of “tasting terroir” as if it were a scientific fact.
"Soil and its water-holding capacity, air flow, slope - these are real things, so matching site to variety is important,” he said.
“The idea of what is ‘typical’ for a particular variety is subjective. On the other hand, though, the more we can grow a variety so that it produces fruit that makes wine strongly typical of that variety, then the more you may be closing in on the right variety for that terroir.
“That’s something I’d really like to investigate in the future,” said the newly minted Euro Master. “Washington is an exciting place because people in the industry are trying all kinds of things.”
Tasty future awaits
Scott is weighing his options going forward. There might be a Ph.D. program in his future, as his study of Washington Rieslings has whetted his palate for a further investigation of the correlation between flavor profile and terroir.
Then again, a burgeoning industry beckons, so it’s entirely possible Scott will apply his knowledge to an endeavor that will endear him to many as a new favorite winemaker.
Learn more about viticulture and enology education at Washington State University, including online courses, professional certificate programs, bachelor of science degree programs, and advanced degree programs by visiting http://wine.wsu.edu.