How Sparkling Wine Is Made

Sparkling wine is wine with bubbles — but where those bubbles come from, and how they were trapped inside the bottle, is one of the most revealing things you can know about a sparkling wine. The method of production has a direct and significant effect on bubble size, persistence, and the complexity of the wine's flavour.

How carbonation works in wine

Carbon dioxide (CO2) is a natural by-product of fermentation — yeast eats sugar and produces alcohol and CO2. In most wine production, the CO2 is allowed to escape. To make sparkling wine, you trap it. There are several ways to do this, and they produce very different results.

The traditional method (Méthode Champenoise)

This is how Champagne is made, and how the best Crémant, Cava, Franciacorta, and Cap Classique are made. It is the most labour-intensive method and produces the highest quality.

Step 1: The base wine. Still, dry, usually quite acidic wine is produced from the grapes (in Champagne: Chardonnay, Pinot Noir, and Pinot Meunier). This base wine will be blended from multiple vineyards and, for non-vintage Champagne, from multiple years of reserve wine.

Step 2: Liqueur de tirage. A precise mixture of sugar and yeast is added to the finished base wine, and the bottle is sealed with a crown cap (like a beer cap). This triggers a second fermentation inside the sealed bottle. The CO2 produced has nowhere to go, so it dissolves into the wine.

Step 3: Lees ageing. The bottles are laid on their side in the cellar, where the wine ages on the dead yeast cells (lees). This is where the characteristic Champagne complexity develops — autolysis (the breakdown of yeast cells) gives the wine its biscuity, brioche, toasty, and sometimes creamy character. Minimum ageing for non-vintage Champagne is 15 months; for vintage Champagne it's at least 3 years. Prestige cuvées (Dom Pérignon, Cristal, Krug) often age 5–10 years.

Step 4: Riddling (remuage). After ageing, the lees must be removed. Bottles are gradually tilted neck-down (riddled) — traditionally by hand over several weeks, now usually by automated gyropalettes — so the lees collect in the neck.

Step 5: Disgorgement (dégorgement). The neck of the bottle is plunged into a freezing brine solution, freezing the lees into a plug of ice. The crown cap is removed, the plug of frozen lees is expelled by the pressure in the bottle, and the bottle is immediately sealed with a dosage addition and a cork.

Step 6: Dosage. The small amount of wine lost during disgorgement is replaced by the liqueur d'expédition — a mixture of wine and varying amounts of sugar. This controls the final sweetness level:

Brut Nature (or Dosage Zéro) — no sugar added, bone dry.
Extra Brut — very small dosage, very dry.
Brut — the standard level; dry, with a touch of sweetness that most people don't notice.
Extra Sec — noticeably off-dry.
Demi-Sec — clearly sweet; a dessert-wine style.

The tank method (Charmat or Martinotti method)

This is how Prosecco, Lambrusco, and many inexpensive sparkling wines are made. Rather than inducing the second fermentation in individual bottles, the base wine undergoes its second fermentation in large pressurised tanks (autoclaves). After fermentation, the wine is filtered and bottled under pressure.

The differences:

Bubble character. Tank-method bubbles are typically larger and less persistent — they dissipate in the glass faster. Traditional-method bubbles (formed under higher, more sustained pressure over longer periods) are finer and last longer.

Flavour. Without extended lees ageing, tank-method wines lack the autolytic complexity (the biscuit, brioche, and toast notes). They tend to be fresh, fruity, and aromatic — Prosecco's selling point is its gentle pear and white peach character, not complexity.

Cost. Tank method is faster (weeks rather than years) and requires less labour. This is reflected in the price.

The ancestral method (Pétillant Naturel)

The oldest sparkling wine method, now fashionable in the natural wine world. The wine is bottled before fermentation is complete, so the first (and only) fermentation finishes inside the sealed bottle, trapping CO2. There is no second fermentation and no disgorgement — the lees remain in the bottle, giving a slight cloudiness. The result (called "pét-nat") is usually lower in pressure (more gentle mousse than Champagne), often slightly funky or yeasty, and always unpredictable. It's wine as it was before the technology of the traditional method existed.

Transfer method

A hybrid: the second fermentation takes place in the bottle (like traditional method), but instead of riddling and disgorgement, the wine is transferred under pressure into a tank, filtered to remove the lees, and rebottled. The lees-ageing character is present but more limited. Used for some Australian and American sparkling wines.

Simple carbonation

The least artisanal method: CO2 is pumped directly into a still wine, the same way soda water is made. The result is large, aggressive, quickly dissipating bubbles. Used only in the cheapest sparkling wine category; rarely seen in quality production.