Most people perceive a cork in a bottle of wine as a simple plug meant to keep the liquid in and the outside world out. In the recent study published in Science Advances, a team of French scientists demonstrated the cork is way more than that. By regulating the oxygen transfer into and out of the wine bottle, it works almost as another ingredient.
“Twenty years ago, our group focused on the oxidation and aging of wine and all its parameters,” Thomas Karbowiak said. “Oxygen diffusion through cork stoppers is one of these parameters.” Karbowiak is a chemist at the University of Burgundy, France, and the senior author of the study.
The mini-bottle experiment #
Oxidation is one of the key drivers of wine aging. A slow, limited ingress of oxygen helps wine mature, smoothing out harsh tannins and bringing out an aromatic complexity. But when too much oxygen gets into the bottle too quickly, it can make the wine stale, brownish in color, and unpleasant to drink. That’s because it will also react with alcohol and phenols in the same process that makes a cut apple turn brown.
The problem with trying to study this is that, in a standard 750 ml wine bottle, the volume of liquid and the thickness of the glass make it difficult to accurately isolate, monitor, and measure real-time oxygen kinetics without introducing external air or disrupting the internal environment. “The real bottle of wine is a complex system. We wanted something simpler and easier to understand,” said Julie Chanut, a researcher at the University of Burgundy and lead author of the study.