There isn't anything quite like a glass of bubbles, and Champagne is queen of bubbly wines. But without the delicate fizz, Champagne would just be another white wine. So how exactly does Champagne get its bubbles? It's all in the second fermentation.
You can't make wine without the process of fermentation, and you can't make Champagne without the second fermentation.
Champagne is made using a time-intensive technique called the traditional method, or méthode Champenoise. In the winemaking process, fermentation begins when the yeasts consume the available glucose and fructose sugars in the grape juice and convert them into carbon dioxide and ethanol. Most fermentation tanks have open tops, which means the CO2 (carbon dioxide) can blow off without getting trapped. Once the juice is converted to wine, a custom blend, or assemblage, is created and bottled.
Once the primary fermentation is done and bottled, a liqueur de tirage (a combination of wine, sugar, yeast, and yeast nutrients) is added to each bottle to kick-off a second fermentation. In this round, the bottle is capped with a crown cap and it traps the CO2 as it is created, ultimately becoming carbonated. Because it had all that pent-up energy developing in the bottle, Champagne has persistent and small rapid bubbles. After the second fermentation is complete, there is a long and tedious process of riddling, disgorging, and bottle aging.
Other Sparkling Wine
Without getting too technical, sparkling wines are basically any type of bubbly wine. While Champagne can only be called so if it is made in the region of Champagne, France, and in the méthode Champenoise style, there are numerous other ways wines can become sparkling.
Most sparkling wines undergo a second fermentation to get their bubbles. Spanish cava and Italian franciacorta are made using the same process as Champagne, but in their distinct regions with their native grapes. Prosecco, on the other hand, is made in the charmat method, or tank method, and undergoes its second fermentation in a large, pressurized tank that traps bulk bubbles.
Another style of sparkling wine is the méthode ancestrale. These wines only undergo one fermentation. The wine is bottled in the midst of fermentation, leaving enough yeast and sugar to create carbonation, which is trapped by a crown cap. These wines are often called pétillant natural, or pét-nats. In lower-quality sparkling wines, a base wine may be injected with CO2 at bottling and capped.
Making Champagne is an intricate and time-consuming process from start to finish, and often the price tag reflects this. But in a quality Champagne, those bubbles are well worth it.