Flute or coupe: CO2 above the glass

The study

Liger-Belair and colleagues measured gaseous CO2 and ethanol just above two glasses filled with the same champagne: a flute and a coupe.¹ Each glass received 100 mL. Both started with about 0.7 g of dissolved CO2, so any difference above the glass comes from the shape.¹

What they found

During the first 15 minutes, CO2 near the rim of the flute was roughly two to three times higher than above the coupe.¹ The reason is geometry. The coupe has a wide, open surface, so the CO2 flux leaving the wine spreads over a large area and mixes with room air. The flute has a narrow opening, so the gas collects in the headspace above the wine.¹

The study also compared temperatures in the flute. Champagne at 12 °C released less ethanol vapour above the glass than the same wine at 20 °C.¹

Flow inside the glass

Shape also changes how the wine moves. Flow visualisation work presented at a symposium found that in a flute the rising bubbles drive a vortex that fills the whole glass and mixes it well. In a coupe the filling height is low, and some liquid near the edge stays almost still.²

What it means for tasting

The gas above the glass is what reaches the nose first, so the shape of the glass changes how the wine is perceived.¹ Neither the flute nor the coupe is the official choice. The Comité Champagne recommends a third shape: a tall glass with a generous bowl that narrows at the top, so the wine can show its aromas and the bubbles can develop.^3,4 This is closer to a tulip or white wine glass. See glasses for the practical advice.

The study measured gas above the glass. It did not score taste, and it does not show that one glass makes a wine better.