Wine is about experience. It’s about a subtle taste and a pleasant buzz. The slow brewing of a drink over months and years. It could also involve knocking down cheap fermented grape juice as quickly as possible. Who should judge?
Some things that probably don’t cross your mind when you consider the wine experience: sauerkraut, marmalade, wet dog. But these scents are produced by a chemical reaction called luminosity when wine, especially white wine and rosé, is exposed to ultraviolet light or high-frequency visible light. According to Fulvio Mattivi, a food chemist at the Edmund Mach Foundation in Italy, “every technician knows about it.” It’s one of the reasons wine is stored and aged in cool, dark places and why bottling methods are so important.
“But then the final decision on what goes to market is up to the head of marketing” for each wine company, said Dr. Mattivi, who, with collaborators, recently published a paper in the Proceedings of the National Academy of Sciences on how bottle color affects the light in wine on supermarket shelves.
White wine and rosé are often sold in clear bottles made of a refractive material called flint glass to show their color, and although standard fluorescent lights in supermarkets don’t produce the same amount of high-frequency light as direct sunlight, the harmful wavelengths are still present. dr. Mattivi’s most recent research shows that just a week on supermarket shelves in these bottles can lead to the “production of foul-smelling compounds.”
“With exposure, you can have a really bad wine,” said Dr. Mattivi.
The winemaking itself is done in the shade. “There’s really no exposure to light until it hits the bottles,” says Gage Oughterson, a winemaker at Highland Cellars Winery in New York. He noted that light strike effects are “definitely a consideration” in the winegrowing world. “Looks like the marketing department won the development department,” he said.
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“The things we bottle in clear bottles are generally wines that have a color that we want to show off,” said Ian Barry, a winemaker in New York’s Finger Lakes who started most of his lighter wines in flint glass bottles. to do, because they sold better in supermarkets. “For example, it’s very important when people decide which rosé to buy.”
Mr Barry added that people interested in naturally produced wine seemed more receptive to emptying bottles. “I don’t know if that’s because they’re literally transparent,” he said.
Frederick Frank, a third-generation winemaker in New York, said that in addition to bottling decisions that stem from a desire to show off wine’s brilliant hues, there is a tradition surrounding the color of wine bottles. In his family’s wineries, semi-dry wines are often bottled in amber, while dry wines are bottled in green. Whatever clear bottles lack in historical significance, they make up for in commercial success. Rosé, chardonnay, sauvignon blanc and pinot gris are all typically bottled in flint glass. “We just hope people don’t leave the bottle in the sun,” said Mr. Frank.
While light strike has been a known effect for at least half a century, winemakers and scientists are unsure of its chemical origins and how quickly it occurred under different conditions. To study it, Dr. Mattivi and his colleagues sell more than 1,000 bottles of wine in an imitation supermarket. This was part of a larger project to understand the effects of shelf storage on wine, stemming from a 2020 paper in which Dr. Mattivi and his colleagues showed that wine in clear bottles developed a bad odor after a few weeks in the store. But what happened at the molecular level?
Wines of different types in bottles of different colors were periodically chemically analyzed. Two aromatic compounds, norisoprenoids and terpenes, which at different concentrations can give the drink a smell of baked apples, flowers, saffron, citrus, spicy cloves or fish oil, were found to be significantly affected in wine stored in clear bottles after just one week. in the supermarket. Wine in green bottles did not show the same kind of chemical change even after 50 days on the shelf, and wine stored out of light remained almost completely stable.
In addition, Dr. Mattivi that the chemical composition of different wines became more similar the longer the wines were kept on the shelf in transparent bottles. “The wine will just be less characteristic,” he said.
“I think there is definitely a perception that a wine in a clear bottle is less severe than wine in a darker bottle,” said Mr. Barry, when told about the new study. He added that knowing the science behind it could change the way he chooses bottle colors.
Mr Oughterson noted how important the new research is to wine connoisseurs, but said: “As long as the stores are running fast enough, I don’t think the average consumer will pick up on anything.”
dr. Mattivi, on the other hand, said wine just shouldn’t be kept in clear bottles. He brought up the folktale of Hans Christian Andersen of an emperor who was convinced by cunning swindlers that his new clothes were beautiful, even though he couldn’t see them. Surrounded by yes-men, the Emperor continued to buy imaginary clothes and eventually donned them to parade through the city. A child, unburdened by social norms, said, “But he’s not wearing anything!”
dr. Mattivi continued: “Wine in clear bottles is naked.”