Researchers have taken on a question that's of great interest in the Modesto area: How do screw caps compare with corks?
The University of California at Davis has launched a study on how different types of closures affect the quality of wine.
Researchers will use high-tech tools on 600 bottles of sauvignon blanc over a year to see how oxygen gets through the closures. Some oxidation is needed to make good wine, but too much can throw off color, flavor and aroma.
"Our goal in this study is to determine if individual bottles might be getting a lot more or less oxygen — and therefore aging at different rates — as a result of the variation in the closures used to seal the bottle," wine chemist Andrew Waterhouse said in a news release.
He told The Bee on Thursday that the $16,000 cost of the study is being covered by the PlumpJack Group, which makes premium wines in the Napa Valley and uses both corks and screw caps.
The latter long have been associated with lower-market products. Among them are Carlo Rossi from E.&J. Gallo Winery of Modesto and Almaden from The Wine Group, which has a winery near Ripon.
Corks also top off some low-price bottles. Bronco Wine Co. near Ceres uses them for its $1.99 Charles Shaw line, better known as Two Buck Chuck.
The Davis team is studying natural corks, made from the bark of oaks grown mainly in Portugal, as well as synthetic corks and screw caps.
It started by obtaining images of the corks with a new type of computed tomography, or CT, scanner invented by John Boone, a Davis radiology professor known for his work in breast imaging.
David Fyhrie, a professor of biomedical engineering at Davis, will analyze the images for differences in the internal structure of the corks.
Every three months, the team will use a spectrophotometer to look for color changes in the wine, which will be kept sealed in clear bottles. PlumpJack provided the wine.
At the study's end, the 600 bottles will be divided into three groups, based on whether they show high, average or low color change.
Finally, the wines with the most and least color change will be opened for chemical analysis, as well as sampling by members of a sensory panel — people good at sniffing and tasting.
"Ultimately, when all of the data are in, we won't be declaring that one type of closure is superior to another," said Waterhouse, who also is working with undergraduate student Jillian Guernsey. "Rather, we'll be giving winemakers information about the variability of each type so that they can determine which is most appropriate for use in bottling their wines."
Bee staff writer John Holland can be reached at jholland@modbee.com or (209) 578-2385.
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