New Research Busts Tannin Additions Myth, Sparks Trans-Pacific Collaboration
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.
The paper discussed in this article, “Impact of exogenous tannin additions on wine chemistry and wine sensory character,” will be published in the April, 2012 issue of the journal Food Chemistry. The paper was published online Oct. 1 and readers with access to a subscribing institution may access the paper by visiting http://bit.ly/wsutannins.
WSU Viticulture and Enology Certificate Grads Are Scoring Points with Critics
Leala Cramer, winemaker and owner of Marcus Sophia Winery, recently scored a coveted 90 points from Robert Parker for her 2010 Viognier. Parker writes: “Marcus Sophia’s 2010 Voignier Lonesome Spring Ranch… offers up a delightful perfume of peach, apricot, mineral, and nutmeg. In the glass it opens to reveal a smooth texture, dry fruity flavors, impeccable balance, and a lengthy, seamless finish. It is an outstanding value in Viognier meant for drinking over the next 3 – 4 years.”
After 20 years as a personal chef working with ingredients produced by Pacific Northwest farmers, Cramer long dreamed of becoming a winemaker and owning her own winery. Cramer took the plunge into the wine business by getting her professional certificate in enology from WSU. “I deepened my knowledge of winemaking” through the certificate program, she says on her web site. No wonder she named her winery after her son, Marcus, and the Greek goddess for wisdom, Sophia. After all, making the best use of knowledge is the definition of wisdom.
Meanwhile, bells are ringing in the wake of critic Stephen Tanzer’s 90-point review of the 2009 Red Willow Syrah from Eight Bells Winery. Eight Bells is owned and operated by three WSU viticulture and enology certificate graduates, Tim Bates, Andy Shepherd and Frank Michiels. Bates started making wine back in 1980. He got Shepherd hooked on winemaking in 1996 and, with their connection to the Boeing Wine Club (birthplace of many a Washington winery), started making wines with some of the best grapes being grown in the Pacific Northwest. Michiels joined forces with the pair in 2006.
The nautical theme of Eight Bells comes from the fact that Bates and Shepherd are National Oceanic and Atmospheric Administration research scientists. When they aren’t making wine, they are sailing the deep blue sea on a research vessel.
Learn more about how you can earn professional certificates in viticulture and enology by visiting http://bit.ly/vecert.
Web-based Grapevine Cold Hardiness Tool Launches on WSU AgWeatherNet System
Just in time for winter, WSU researchers have launched a web-based Grapevine Cold Hardiness tool. Based on mathematical simulations of how grapevines respond to cold temperatures throughout the winter, this tool provides estimated low temperature thresholds for bud damage of over 20 wine and juice grape cultivars.
With AgWeatherNet stations across the entire state, the Grape Cold Hardiness tool enables growers to closely monitor temperatures at their vineyard sites and see, in real time, potential effects on their grapevines. The damage thresholds programmed into the tool represent temperatures that would kill 10, 50, and 90 percent of a particular variety’s primary buds. If a temperature threshold is reached, a warning statement indicating the estimated level of damage appears on the Grapevine Cold Hardiness tool’s web page. These real-time observations can be found at http://bit.ly/wsuvecold, the WSU Viticulture and Enology Extension cold hardiness web site.
In the fall, grapevines “harden off,” becoming more cold hardy as temperatures decline. The Grapevine Cold Hardiness tool web page indicates how well a particular cultivar is developing cold hardiness in response to local temperatures.
The tool is available online starting Dec. 1 at http://bit.ly/wsucoldhardiness. In order to access the tool, you must be a registered user of AgWeatherNet. Registration is free and an online help system is available on the page. A short how-to video on using the tool can be found on the WSU Viticulture and Enology Extension cold hardiness web site at http://bit.ly/wsuvecold. This site also contains valuable information regarding preventing, assessing, and responding to cold damage in vineyards.
To prepare Washington growers for dealing with cold damage, WSU’s team of viticulture experts has published a grapevine cold-damage management guide, available as a free PDF download from http://bit.ly/wsucolddamage.
Check out WSU Viticulture and Enology Extension’s YouTube channel at http://bit.ly/sAeR2u. You can connect with the V&E team on Facebook, too: http://on.fb.me/j5jipq.
Raise a Glass, Fund a Scholarship
Nearly 150 restaurants around the Puget Sound are participating in Chateau Ste. Michelle Wine Estates’ 4th annual “Raise a Glass, Fund a Scholarship.” We are grateful to Chateau Ste. Michelle and all the restaurants participating in this program. We are even more grateful to all of you. Last year, you helped raise $40,000 for WSU’s wine science education program.
The way it works is simple: visit a participating restaurant and order wine that supports WSU’s viticulture and enology program. The list of participating restaurants (with addresses) is online at http://bit.ly/fundveedu.
WSU Cougars Mediterranean Cruise
Join world-renowned WSU Viticulture and Enology Director Thomas Henick-Kling, CAHNRS Dean Daniel Bernardo ‘85, and other WSU and Cougar wine community leaders as they sail the Mediterranean on a private Cougar-chartered cruise, May 28 – June 2, 2012. Embark from Nice, France, and call at Calvi, Portofino, Livorno, Portoferraio and Rome.
Special pricing for the first 42 cabins start at $2,450 pp. Proceeds will benefit the WSU Viticulture and Enology program.
WSU Cougars Cruise pricing includes:
- All meals and snacks aboard ship
- Special gourmet wine tasting dinners prepared by our celebrity chef
- Featured wines served all day and evening throughout the cruise
- Special WSU Cougars wine tasting events
- Winemaker seminars
- Educational seminars on wine, food, and ports of call
- Special parties aboard ship
- Two special WSU cocktail parties with complimentary drinks and appetizers
- Live entertainment every night
- 24-hour room service
- Water sports at the Windsurf marina, including water skiing, sailing, and kayaking (weather permitting)
- Airport transfers in Nice and Rome
Learn more at http://bit.ly/cruisewine.
Voice of the Vine is taking a month off to celebrate the winter holidays. We’ll be back with another issue on Jan. 26. Until then, stay warm! Cheers, the editors.