Which fermentation step creates the carbonation characteristic of traditional sparkling wine production?

• A. Primary fermentation of grape juice
• B. Secondary fermentation in tank
• C. Secondary fermentation in bottle
• D. Carbonation by injecting CO2

Answer: (C)

The bubbles in traditional sparkling wines come from a second fermentation that happens inside the bottle. After the base wine is made, a tirage mixture (sugar and yeast) is bottled with it and sealed. The added yeast ferments the sugar again, producing alcohol and carbon dioxide. Because the bottle is sealed, the CO2 can’t escape and is dissolved into the wine under the bottle’s pressure, creating the characteristic sparkle. This bottle-fermentation step is what distinguishes traditional method sparkling wine from other methods. Primary fermentation in the tank can produce CO2, but the sparkling effect in the traditional style specifically arises from fermentation that occurs in the bottle. Fermenting in a tank or injecting CO2 would not yield the same bottle-aged, naturally carbonated character.