Sparkling wine is characterized by the presence of carbon dioxide (CO2) bubbles dissolved in the liquid. There are several reasons why wine can be made sparkling:
Fermentation: In the traditional method of producing sparkling wines, known as the "champenoise method" or "classical method", the base wine undergoes a second fermentation in the bottle. During this fermentation, sugar and yeast are added to the base wine sealed in the bottle. Fermentation produces alcohol and carbon dioxide as byproducts. Because the bottle is sealed, the carbon dioxide cannot escape and dissolves into the wine, creating bubbles.
Fermentation in pressurized tanks: As an alternative to the champenoise method, sparkling wines can be produced in large pressurized tanks. In this case, the second fermentation takes place in a controlled environment, where the carbon dioxide produced is retained inside the wine due to the pressure. The wine is then filtered and bottled.
Carbon dioxide injection: In some cases, carbon dioxide is added directly to the wine in an artificial way. This method is often used to produce slightly sparkling or slightly effervescent wines.
Maturation on yeasts: Some sparkling wines can obtain their bubbles through prolonged maturation in the bottle, during which the residual yeasts present in the wine continue to ferment the sugars, producing carbon dioxide.
The intensity of the bubbles in the wine can vary. Some sparkling wines, such as Champagne, have fine, persistent bubbles, while others may be more lightly sparkling.
It is important to note that there are also "sparkling" wines that have a very high level of effervescence, such as Champagne, and "sparkling" wines that have a more moderate amount of bubbles. The presence of bubbles can influence both the visual appearance of the wine and its sensorial perception, influencing aroma, taste and structure.