(Komonews) - They don't stand on snobbishness when it comes to making wine at Washington State University.

For the past six years, every wine made by a WSU enology student or researcher has come with a screw cap.

"It's the best technology for closing wine in a glass bottle," said Thomas Henick-Kling, director of WSU's Viticulture and Enology program.

When Washington State scientist Walter Clore's research helped create the state's wine industry in the 1930s, cork was the only method for sealing a wine bottle.

But that has changed, as aluminum screw caps have started to replace the venerable cork across the industry. Screw caps have since moved from the cheapest wines to higher-priced offerings, as winemakers seek to avoid a problem called cork taint.

Since wines started flowing into glass bottles in the 15th century, corks made from the bark of the cork oak tree have been the main stopper. Today, about 80 percent of the world's 20 billion bottles produced each year are sealed with cork, WSU said. But the rest are sealed by either screw tops, synthetic corks or glass stoppers.

Cork taint can wreck as many as seven bottles of wine out of a hundred, putting a moldy, musty, off-putting smell inside that expensive bottle of chardonnay.

Two compounds, known as TCA and TBA, are responsible for most cork taint, said Jim Harbertson, WSU associate professor of enology. They develop anywhere that wood, water, chlorine and microorganisms combine.

"Dump chlorinated water onto wood or cardboard, and boom, you have TCA," Henick-Kling said.

In WSU's Blended Learning program in Pullman, enology students learn how to make and market their own wines over the course of a year. Blended Learning produces only small batches of wine, usually under 200 cases.

Not only are bad corks a problem for commercial winemakers, but they can ruin wine research.

"We cannot simply discard several and look for one with a good closure," Harbertson said. "Every bottle needs to reflect the quality of wine produced for a particular research project."

Bigger wineries have switched to caps for the same reason.

"If a consumer opens their wine, and it happens to be corky and they don't like it, they may not know it's the cork. They blame the winery," said Henick-Kling.

Washington has hundreds of premium wineries and many of them use screw caps exclusively, said Michaela Baltasar, communications director for the Washington Wine Commission in Seattle.

The commission does not have exact numbers, but she said they have definitely become more commonplace.