Boosting Resveratrol in White Wines

Missouri researchers develop new yeast strains to potentially enrich health benefits

by Jane Firstenfeld
Danforth Plant Science Center
The transgenic yeast was developed at the Danforth Plant Science Center at St. Louis Community College.
St. Louis, Mo.—The well-known antioxidant health benefits in red wines may be shared by white wines in the not-too-distant future, if experimental yeasts under development at a St. Louis laboratory find commercial acceptance. Dr. Oliver Yu, adjunct associate professor at St. Louis Community College’s Donald Danforth Plant Science Center, has been working on yeast as a background to produce plant compounds, including flavonoids.

After several years of experimentation, Yu and his team developed a branch of transgenic yeast that can make resveratrol, a polyphenol abundant in red winegrape skins that is widely believed to provide health benefits including antioxidants and reduction of blood sugar. Although the skins and seeds of white winegrapes also contain resveratrol in lesser quantities, most of these are lost during crush.
Dr. Oliver Yu, Danforth Plant Science Center
Dr. Oliver Yu, Danforth Plant Science Center
Almost half of U.S. wine drinkers prefer white wines, and many have intolerances to red wines for as-yet undetermined causes. So building additional health benefits into white wines could be hugely beneficial to both the public and the wine industry. As with most genetic research, though, the path to commercialization is arduous and time consuming.

Hank Johnson, who owns 6,000-case Chaumette Vineyards & Winery in Ste. Genevieve, Mo., told Wines & Vines he has been working on the yeast project with Yu for two years. Limited by a non-disclosure agreement, he commented, “It’s safe to say, we’re providing the raw materials” for the winemaking research.

He revealed that the St. Louis Community College labs had produced “sufficient quantities of yeast,” and termed his involvement “a wonderful experience.” The Danforth Center, he said, “is a big deal here in town. I couldn’t believe the biotechnical labs there. We used the biofermentors in their labs; they are doing a great job for the wine industry.” Indeed, Missouri’s academic community has become a leader in wine-related genetic research.

What is that yeast?
In 2006, Yu and his colleagues published preliminary results of the transgenic yeast research in The Journal of the American Chemical Society. As Yu summarized it for Wines & Vines, “We transformed three genes: TAL, a bacterium; 4CL, sourced from a weed; and STS, from a grape.” Together, Yu said, “We were very happy to make resveratrol.”

The project started, he explained, as pure research to understand the mechanisms plants use to defend themselves. Scientists believe that grapes use resveratrol to fight pathogens.

Chaumette Vineyards
Chaumette Vineyards & Winery provided "raw material" for the white winemaking experiments.
Because the yeast is a true transgenetic organism, Yu acknowledged, bringing it to market raises massive hurdles. “We are paying extreme attention to all regulatory issues. We work under utmost standards, and the yeast are never released without proper control,” he emphasized. “We took a lot of time setting up controls. We are being very careful.”

Hybridizing grapes to create beneficial crosses takes years or decades. Yeast, on the other hand, “can be bred very quickly,” Yu noted.

According to Johnson, the developers have already propagated some 7 trillion yeast cells and are working on a patent now. When and if these find a commercial market remains a question.

Several years ago, Yu said, “We contacted Constellation Wines” hoping to secure industry support for the project. Although Constellation participated in some experiments, he said, “Eventually, they did not invest.”
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