Whether it's midnight on New Year's Eve, or time to toast your favorite bride and groom, the bubbly texture in a glass of freshly poured champagne will tickle your nose and cause you to smile. A famous quote, often attributed to Benedictine monk Dom Pierre Pérignon, compares sipping the effervescent wine to "drinking the stars." But what puts the sparkle in champagne? And why do the bubbles form in patterns of trains?
Physics of Bubbles
Why champagne bubbles is no secret to science: when you pop a champagne cork, yeasts ferment sugars and form carbon dioxide gas (CO2). The effervescence process, which enlivens champagne, is the result of the fine interplay between CO2 gas molecules, tiny air pockets trapped within microscopic particles during the pouring process, and some liquid properties. Temperature plays an important role in this process - unlike many solids which dissolve in water, the amount of CO2 able to dissolve goes down as the temperature rises, which is why it is good to keep champagne chilled. The cooler the champagne, the more CO2, and, in turn, the more bubbles you will have in your freshly filled flute.
Scientific Results on Bubble Trains
Pieces of dust or lint on the walls of the champagne glass allow bubbles to nucleate (begin), forming different patterns of bubble trains, those tiny beads of rising air that give champagne its sparkle. If you want lots of bubbles, don't wash your flutes in a dishwasher - hand wash and use a cloth to dry the glasses to ensure lint.
The bubble trains in champagne rise to the top of the glass in a mathematical problem that changes over time, according to Associate Professor Gerard Liger-Belair, of the University of Reims. Taking snapshots of a glass of freshly poured champagne and looking closely at the bubbles, Liger-Belair and his team saw pairs of bubbles rising in strings that, over time, rose in groups of three before settling down into a string of evenly spaced single bubbles. The researchers developed a mathematical model that shows the variations in bubble patterns depend on factors such as temperature and the concentration of dissolved CO2. The main parameters for the rate of bubble formation are temperature (the higher the temperature, the higher the bubbling rate), and viscosity (the bubbling rate is inversely proportional to the viscosity, which is itself related to the sugar content). A very sweet champagne, having a high sugar content, will have a lower bubbling rate.
You can read more about the process and the mathematical model and view the photographs of bubbles in Liger-Belair's book, Uncorked: The Science of Champagne. In the meantime, should you find yourself holding a champagne flute and "drinking the stars," consider, for a moment, the science behind the romance.
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