Finish Your Wine: WSU Researchers Explore White Wine Finish and Consumer Preferences

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.

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?

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 choose 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.”

New Research Busts Tannin Additions Myth

If you’re using tannin additions in your red winemaking process, you may well be wasting your money, according to recently published research by Washington State University enologist Jim Harbertson and Australian wine and grape researcher Mark Downey, a lead researcher at Victoria’s Department of Primary Industries.

Harbertson, Downey and their colleagues analyzed commercially available tannin additives and found them to be, at best, an unnecessary expense for red wines made from Washington-grown grapes.

Many winemaking manuals recommend adding tannins, though, in the belief that the additions help bolster mouth feel and improve color in red wine. A red wine’s mouth feel is the result of a range of chemicals causing astringency and is described with a variety of words ranging from “velvety” to “drying.”

“At the recommended dosage, these additives are, at most, giving a slight tweak to astringency,” Harbertson said. “In higher doses, you get some aroma shifting and a negative impact on sensory character. It made them earthy tasting, and turned the wine brown.”

Harbertson and Downey collaborated with renowned sensory scientist Hildegarde Heymann, professor of enology at UC Davis, and her Italian post-doctoral student, Giuseppina Parpinello, to conduct sensory analyses of Merlot and Cabernet Sauvignon wines made with tannin additions. “In a collaboration with Chateau Ste. Michelle, we added commercial tannin products to both barrel-aging Merlot and to Cabernet Sauvignon after pressing the grapes,” Harbertson said. “We used a range of concentrations and a variety of commercially available additives to get a sense of what is going on when these products are added to Washington wines.”

Harbertson explained that there is a crucial difference between taste (flavor, aroma) and astringency, or mouth feel. “Mouth feel is a tactile sensation,” he said. “It’s basically the removal of the lubricating proteins that naturally occur in the mouth. Aroma and flavor, in contrast, are receptor-based and are caused by our taste buds being stimulated by the flavor and aroma molecules in wine. Astringency is thought to be a result of chemical precipitation in which tannin molecules bind the lubricating proteins in the mouth, thus taking them out of action. That’s why some wines have a drying or ‘spikey’ mouth feel, as the overabundance of tannins rob the mouth of its lubricants.”

Not only did the additives have a limited or negative impact on wine quality, analysis of the products revealed them to be, at most, only 48 percent tannin. “On the low end, we found some products to contain as little as 12 percent tannin,” Harbertson said. The products contain fillers that enable the additives to go into solution more easily. Harbertson and Downey conducted the analysis of the tannin additives.

“The bottom line for Washington red winemakers is this,” Harbertson said. “We have plenty of naturally available tannins available in red grapes grown here. In an industry with tight margins and dealing with global competition, we are suggesting that the extra expense of adding tannins is simply unnecessary.”

Downey observed that “Tannins additives are one of the many tools available to winemakers in Australia and have been used extensively by some producers without a clear understanding of their impact. Some winemakers consider their addition essential, while for others it is more of an insurance policy, but neither approach is based on science. Given that tannin additions are an added cost, understanding their impact may result in cost-savings for producers. In the current economic climate, this is of considerable interest.”

Harbertson speculated that tannin additions might control some problems faced by white wine makers, such as protein haze or Botrytis. “But this idea has not been scientifically tested,” he pointed out.

Harbertson also mentioned that certain hybrid grape varieties, once grown in Europe for their resistance to diseases and pests, don’t produce much tannin on their own, so an additive is needed. However, most hybrids aren’t grown in Europe simply because they produce wine that is too acidic for most consumers. Several hybrid varieties are still grown on the east coast of the U.S. and in Ontario, Canada, where they are popular as constituents of the ice wines enjoyed in the region.

“This study shows us what happens when you add tannins at one end of the spectrum. What we need to do is look at the other end: adding tannins to wines from low-tannin regions or fruit grown in high volumes in a warm climate. Not all of these conditions are present in Washington or Victoria (or convenient to our research programs) so it makes sense to work together,” said Downey.

Downey said that his and Harbertson’s research programs “are complementary rather than competitive. The knowledge earned from scientific research doesn’t give you a competitive advantage. Rather, it’s how growers and winemakers use that knowledge that gives you the advantage. Working together actually achieves more for our respective industries. By collaborating and sharing the load, the Washington industry gets more research outcomes for the same research dollar invested and so do we.”

Indeed, Harbertson and Downey plan to continue their collaborative research. Among other things, they will be investigating the effects of aging red wines in oak barrels. Like so much of their work, both together and individually, the role of oak and oak’s contribution of tannins, in wine quality is assumed but not well understood. Indeed, this and other questions have led the scientists’ respective institutions to sign a formal agreement, allowing them to collaborate over the long term in ways that would not otherwise be possible.

A (Very!) Brief History of Washington Wine

I’ve been running around the state trying to capture the stories of some of Washington’s wine industry pioneers. The video below is one I made for a recent WSU viticulture and enology program fundraiser, so its very short — but a lot of fun. Hopefully I’ll find the resources to produce a full-length documentary on this subject.

Seven Ways to Puncture a Wine Windbag

By Richard H. Miller/Washington State University

Uncle Patrick gargles his wine. “I taste blackberries and cherry and oak,” he says, “and a lot of tannins.”

The only thing you know about wine is that it comes in different colors. But, with holiday meals approaching, here’s how to puncture wine windbags, thanks to Washington State University Professor Kathleen Williams:

Precipitate saliva. When Patrick says he tastes tannins, you say: “Tannins don’t have a taste. They create a sensation as they precipitate the proteins out of your saliva.” Tip: Stroke your chin sagely as you pronounce “precipitate.”

Throw in a German word. Patrick swirls the glass. “Good legs,” he observes. You say, “The French call them tears. The Germans call them Kirchenfenster or church windows, because they form an arch.” Want more? Try this: “Water has more surface tension than alcohol. The evaporating alcohol pulls the water up with it. When the alcohol breaks through, the water runs down.”

Hit him with Brix. Patrick looks at the label. “Oh my,” he says, “14.9 percent alcohol.” You’re ready for him. “Did you know that wines from hot areas tend to have more alcohol? That’s because the grapes have more sugar. As a rule of thumb, every 2 percent of sugar will produce about 1 percent alcohol. So this wine was originally almost a third sugar. Of course, wine makers don’t call them sugars. They call them Brix.” Tip: Refill his glass. Keep refilling his glass. This becomes important later.

Diamonds are your best friend. He holds the glass up to the light. Tiny crystals stick to the sides. “It’s going bad,” he says. “Not really,” you say. “Those are potassium tartrate crystals, same thing as cream of tartar. They’re a naturally occurring acid in grapes.” Smile tolerantly, and add, “In Canada, they call them wine diamonds.”

Herbal harmony. Patrick says, “A red wine would overwhelm the turkey.” You say, “It’s not really about the turkey. It’s about the herbs with the turkey, such as onion, celery and sage. What works well is to contrast the herbs with a fruity wine, such as a Beaujolais Nouveau or a Gewürztraminer.”

Make something up. By now, Uncle Patrick should be a bit toasted, so hit him with something ludicrous, but difficult to disprove: “Gewürztraminer has an umlaut,” you say. “The word umlaut is derived from the word omelet and Gewürztraminer pairs well with omelets. As a matter of fact, most umlaut wines go well with egg-based dishes, such as quiche. It’s called a bio-linguistic reaction.”

Fancy footwork. As he sputters to object, quickly change the subject: “Do you know what the best pairing is? Scientists in England proved that it is milk and chocolate chip cookies. Speaking of dessert, how about some pie?”

WSU’s viticulture and enology program offers both undergraduate and graduate degrees, and certificates. For more information go to http://wine.wsu.edu/education.

Disease Detectives Tackle the Mystery of the Fall Colors

WSU plant pathologist Naidu Rayapati and his colleagues are carefully unraveling the intricate biochemistry and molecular biology of grapevine leafroll disease.

Grapevine leafroll is a complex viral disease that can cause a marked decline in grapevine vigor, grape quality, and fruit productivity, according to Rayapati. The disease can reduce yields as much as 50 percent or even more, depending on the severity of infection. A few years ago, it was estimated that nearly 10 percent of Washington’s vineyards have grapevine leafroll disease. Anecdotal evidence suggests that the disease is more wide spread than previously thought, raising alarm among industry stakeholders. Grapevine leafroll disease accounts for about 60 percent of the production losses of grapes worldwide, Rayapati said.

One of the most perplexing questions Rayapati is addressing is one of symptomology: why do some grape varieties show the “fall colors” symptoms in their leaves while others do not?

Chinese Market Thirsty for Washington Wine

Economists at Washington State University are investigating ways to market Washington wine to the growing Chinese consumer market.

The research consists of examining Chinese preferences for wine from different countries coupled with economic experiments, said economics professor Jill McCluskey.

“It is important to understand Chinese consumers’ preferences so the United States can enter this growing market,” McCluskey said. “There is great potential within this market.”

China is one of the most populous nations in the world, and currently, per capita wine consumption within China is at 0.3 liters. This is meager in comparison with France and the United States, which are set at 59 liters per year and 12 liters per year, respectively.

“If per capita wine consumption in China rose by just 0.1 liters per year, that would mean consumption would rise by 100 million liters,” said Hainan Wang, a graduate student who assisted McCluskey in the study. “There is so much potential to create incredible profits by marketing wine to China.”

Currently, Chinese consumers perceive wine as stylish and prestigious. The Chinese prefer imported wine, and there is a preference for French wine among consumers, McCluskey said.

Going Pro with Online Wine Science Education

When Higher Learning recently talked to students in the WSU professional certificate program in enology, we learned that they not only come from all over the country, they’re also making connections, starting businesses and getting jobs in wine regions all over the place. Hear what certificate program students have to say in this short video.

The two-year certificate programs in viticulture and enology are continuing education programs offered through Washington State University Extension. These non-credit, professional certificate programs are tailored for people who are seriously interested in working in the wine industry — grape growing and winemaking — but are not interested in obtaining a college degree.

Mapping Complexity in Washington Wine Country

As you read this, a graduate student in Prosser is sitting in front of his computer, for the umpteen millionth hour, bashing his head against the mapmaker’s perennial problem: the map can never be as detailed as the terrain it represents.

But that doesn’t mean the mapmaker doesn’t try. Especially when there is tremendous pent up demand from Washington grape growers for a vineyard site-selection tool.

Ian Yau is the mapmaker, and he’s a grad student based at WSU’s Irrigated Agriculture Research and Extension Center in Prosser. Yau is trying to wrestle a vast amount of information to the ground in order to turn raw data into useful knowledge.

“It’s a lot of spreadsheet manipulation,” Yau said, the wry understatement of his project causing a smile to play across his face.

Consider what you’d want to know if you wanted to plant a vineyard in Washington. You’d want to know, of a given plot of land, how many growing degree days it got at a certain elevation on a particular slope. You’d want to know about the soil beneath your feet: is it going to drain properly so the grape vines don’t wallow and rot? Is there hardpan or some sort of other restrictive layer close to the surface that will prevent the plants from sinking their roots deep into the soil? And what’s the soil’s water-holding capacity and pH?

The Mendoza Connection

When Daniela Romero heard Washington State University’s Markus Keller talking about irrigation during grape ripening, her curiosity was piqued. After all, applying water close to harvest time was simply not done.

Keller was teaching a grape physiology course at the Universidad Nacional de Cuyo in Mendoza, deep in the heart of Argentina’s wine country. Romero is a graduate student at the university, and she asked if she could join Keller’s research team in Prosser to learn more about his tradition-defying research.

“Keller’s research is important to the wine industry, because it will influence the way growers add water to their vineyards. In most of the world’s wine regions, irrigation during grape ripening is thought to dilute the sugars in grapes–but this belief does not have any scientific foundation,” Romero said.

As Keller pointed out, “The European wine industries and their many regulators have it all figured out: irrigation during grapes’ critical ripening period is generally a bad thing and must be strictly regulated.”

A quote from the International Organization for Biological and Integrated Control in their 1999 Guidelines for Integrated Production of Grapes illustrates Keller’s point: “Irrigation of vines for wine production will not be applied after véraison or highly restricted by the regional guidelines in order to guarantee the good quality of the wine.”

“The tacit assumption is that irrigation boosts berry size and dilutes the quality-impact components of the grapes,” Keller said. “So pervasive is this argument that, even in the New World, many wineries encourage growers to withhold irrigation water during fruit ripening to avoid any perceived adverse effects.”

Keller and former graduate student Marco Biondi put the assumptions to the test–with startling results that fly in the face of viticultural tradition.

The Fine Details: The Ability to Blend Art and Science Helps Make Great Wines

When sipping a glass of a fine winemaker’s red blend in front of the fire, it’s easy to appreciate the art that went into that glass.

But anyone who has tried to make wine finds him or herself quickly caught up in what amounts to a science project.

“Winemaking is certainly creative,” said Carolyn Ross, assistant professor of food science at Washington State University and an expert in the sensory analysis of wine. “But at its core, winemaking is a scientific endeavor. What folks often forget is that those two things are not incompatible.”

Take the fine art of fining, for example. Fining agents are substances added at or near the end of the winemaking process in order to improve clarity, adjust flavor, aroma and wine stability. In other words, fining tweaks a wine’s sensory qualities.

And the sensory quality of wine is, of course, what enjoying a glass of great wine is all about: the mouth feel, the unfolding bouquet, the color, the acids, tannins, and other qualities that wine writers deploy armies of adjectives trying to describe. Ross takes a scientific approach to those armies of adjectives be finding ways to quantify their chemical properties and by training panels of wine tasters to communicate the importance of individual sensory qualities.

“Fining is critical for consumer acceptance of white wines as a haze or sediment in the bottle may eventually lead to consumer rejection and economic loss to the winery. Together with racking and filtration, fining agents improve clarity, define aromas and increase shelf life,” Ross and her colleagues wrote in a recently published article in the American Journal of Enology and Viticulture.

But, the researchers add, fining may also “impact the sensory quality of wines,” though how much sensory impact fining has depends upon a complex relationship between the fining compound and the type of wine being fined.

“Fining is definitely where some basic scientific practice is essential to making a good wine,” said Ross.

Ross and her team fined Chardonnay and Gewürztraminer made by a well-known Washington winery which donated the wine to Ross’s team specifically for this series of experiments.

“There’s hasn’t been a lot of research done on the fining of Washington wines,” Ross pointed out. Because wine is so chemically complex, it is very “place specific”: grapes of the same variety grown in different areas produce wines with varying sensory qualities and so research, too, needs to be place specific.

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