Wine nerds pursue tartaric acid

Owen Flynn likes the fact that he gets an antioxidant boost with every glass of wine he consumes. But the liquid's nutritional value is just icing on the cake for him.

"It's all about the finish," said the Sacramento contractor while shopping Thursday at Taylor's Market in Sacramento. "It's all about the flavor."

Unraveling some of the molecular mysteries that make wine both healthful and delicious is a focus for scientists around the world.

While deconstructing the grape for its most basic metabolic properties may not seem a romantic way to appreciate a good bottle of wine, it has enthralled an intercontinental team of researchers.

Scientists from UC Davis and the University of Adelaide in Australia teamed up in the past few years to zero in on one compound that most influences a wine's taste and feel in the mouth, its color and its longevity in the bottle: tartaric acid.

"A little will be quite good, but more can be very good," explained Chris Ford, a senior lecturer in enology at Adelaide University. "Wine is all about balance. A wine with no acid is horrible. Flabby. Jammy. Soapy."

It is well known in wine science circles that this natural and abundant material in grapes is synthesized from vitamin C. But scientists had not identified any of the specific enzymes responsible for the synthesis -- until now.

In a paper published online last week by the Proceedings of the National Academy of Sciences, the researchers report their discovery of the key gene within the grape that helps in that conversion.

Why should wine lovers care?

Getting a better handle on how grapes make tartaric acid will help vintners make a crisper sauvignon blanc or avoid producing a soapy Semillon, said Doug Cook, a plant biologist at UC Davis whose work on the grape genome provided the foundation for the discovery.

"There is a big black box of knowledge between growing a plant and the final outcome of the wine," he said. "One possible outcome (of this research) is a refined or more precise viticulture," the science of grape cultivation.

It could also save winemakers a lot of money, said Ford. In Australia, where winemaking is a huge industry, growers spend millions of dollars per year buying tartaric acid for wine production.

"We now have people drinking Australian wine," Ford added. "The task of the industry now is to keep those people drinking it and not moving on to the next great thing. We can produce what the customer wants, but we need to know what they are after."

While the latest discovery could yield a better tasting and less costly wine, it could also help scientists engineer table grapes -- and possibly even wine -- to produce more vitamin C.

While the researchers' goal is not to make a healthier glass of zinfandel, they don't discount the potential. Their investigation revealed that wild grapes lacking the gene also lack tartaric acid and contain more vitamin C. Blocking the conversion of vitamin C to tartaric acid could boost the vitamin C content in the grape.

"This does clearly show the potential to engineer grapes for high levels of vitamin C," said Seth DeBolt, a plant biologist whose interest as a postgraduate student at UC Davis spurred the research. "It's of interest to both the winemaking side of grape research and the table grape side. It has huge benefits for both, depending on whose side of the bench you're on."

From Flynn's perspective any innovation to enhance his favorite libation is worth a toast.