How do bubbles form in sparkling wine during pouring?

• A. Bubbles form when nitrogen is infused
• B. Bubbles are produced only by distillation
• C. Carbonation is independent of pressure
• D. Bubbles form when pressure is released during pouring

Answer: (D)

Bubbles form during pouring because sparkling wine is bottled under pressure with dissolved carbon dioxide. When you pour, the liquid meets lower pressure at the surface, and CO2 becomes less soluble in the liquid (Henry’s law). The gas escapes from the solution and appears as bubbles at nucleation sites—tiny imperfections on the glass or particles in the wine—then rises to the surface. This release of dissolved CO2 is what creates the characteristic fizz.

The other ideas aren’t accurate here: there isn’t a nitrogen infusion in standard sparkling wines, carbonation isn’t produced by distillation, and carbonation is not independent of pressure—it's driven by the gas’s solubility under the bottle’s pressure and the drop in pressure during pouring.