Wine may be healthy for your heart, and help prevent other ailments, but chemicals in a common by-product of red wine production may “significantly reduce the ability of bacteria to cause cavities,” according to a study recently released by a team of researchers at the University of Rochester Medical Center and the New York State Agricultural Experiment Station at Cornell University.
The research was funded by the USDA, and the findings published in the Journal of Agriculture and Food Chemistry, and reported on by Wines & Vines.
Led by Hyun Koo, DDS, Ph.D., the scientists found that specific polyphenols found in large amounts in fermented seeds and skins – known as pomace, and normally discarded in the process of red winemaking – actually interfere with the potency of Streptococcus mutans, the microbial culprit behind dental caries; and glucans, the building blocks of plaque.
“We thought grapes and pomace could be a potential source for these bioactives, especially considering that they are largely available,” Koo told Wines & Vines.
To prepare polyphenolic extracts, the team used pomace donated by wineries in New York’s Finger Lakes region: Cabernet Franc from Cornell Orchards, Baco Noir from Pleasant Valley Winery, and Noiret from Swedish Hill Winery. Cameron Hosmer, at Hosmer Winery, recalled contributing about 100 pounds of his vintage 2005 Pinot Noir pomace to the project. Varieties were pre-screened for their phenolic content. Red grapes have been shown to contain 40% more phenolic content than white grapes.
The researchers were most interested in examining the impact of grape polyphenols on two capabilities of S. mutans that enable it to survive in the human mouth. According to their report, “First, it secretes enzymes known as glucosyltransferases (GTFs) that produce the sugary, glue-like substances -glucans – that firmly attach bacteria to tooth surfaces and form a tough barrier around bacterial colonies.”
These barriers protect the bacterial colonies against environmental assaults, such as toothbrushing, and make them, in some cases, “hundreds of times more resistant to antibiotics.”
Another source of S. mutans damage is its ability to secrete acid and to survive that acid. “Having evolved to be ‘acid durable,’ S. mutans can survive and out-compete other bacteria in the mouth,” the report continued.
Results revealed that all of the grape varieties inhibited two bacterial GTFs by as much as 85%, unprecedented in Koo’s experience. “Cabernet Franc extracts were more effective GTF inhibitors, with Pinot Noir a close second at concentrations that might be useful therapeutically,” the report said. “Grape polyphenols were also found to cause S. mutans to produce significantly less acid… None of the extracts from any variety killed the bacteria outright.”
As winemakers and tasters are painfully aware, wine itself is acidic, and can cause severe erosion of tooth enamel. For that reason, Koo emphasized, “We make it clear that we used chemical fractions of grape extracts devoid of acids and naturally occurring sugars (another substance that can be detrimental to tooth integrity, since it can be fermented to acids by oral bacteria). So, do not run into the liquor store and start rinsing with wine.”
One application of the research, however, would be some type of mouthwash containing the beneficial polyphenols to protect the teeth. The project is continuing. “We are currently trying to identify the bioactive polyphenols. This is critical before planning any potential rinse formulation,” Koo said.