Technique
Prise de Mousse
The second fermentation in the bottle for Champagne and other méthode traditionnelle wines. Yeast eats added sugar, produces alcohol and CO₂. Takes 6 to 8 weeks at 10-12°C.
What it is
Prise de mousse literally means “taking up of mousse”. It is the second fermentation in the bottle, the phase in which a still base wine becomes sparkling Champagne. Not to be confused with the first fermentation (must fermentation) that happens right after harvest.
The step begins with tirage: the base wine is bottled together with a mixture of sugar and yeast (the liqueur de tirage). Under the crown cap the prise de mousse then happens: yeast eats the added sugar, produces ~1.5% additional alcohol and the CO₂ that creates the bubbles.
How it works
Per Comité Champagne specs the prise de mousse works as follows:
- Tirage: base wine + 24 g/l sugar + yeast + clarifier, combined just before bottling.
- Bottling: bottle closed with crown cap, not the final cork.
- Stored horizontally in cool cellar (10-12°C).
- Fermentation runs: 6 to 8 weeks for full consumption of the added sugar.
- Pressure rises to ~6 bars (comparable to a truck tyre).
- Yeast dies off after consuming all sugar. The cells remain in the bottle for autolysis.
Temperature is critical. Above 15°C the fermentation runs too fast and produces coarser mousse. Below 8°C the yeast stops working. Between 10-12°C a fine, slowly building mousse develops: the hallmark of Champagne quality.
Where it gets misread
The standard explanation says: “Champagne is bubbly because it ferments in the bottle”. That’s true but hides an important nuance. The first fermentation (still wine making) happens in tank or vat, not in bottle. The second fermentation (prise de mousse) is what makes the bubbles. Two separate phases, sometimes months or years apart.
Second misconception: prise de mousse is not the same as autolysis. Prise de mousse creates the bubbles (6-8 weeks). Autolysis breaks down the dead yeast cells (months to years). Both happen in the same bottle, but in successive phases with entirely different effects.
When to stop
The prise de mousse lasts until all added sugar has been consumed. With standard tirage (24 g/l) that delivers ~6 bars of pressure. Above that pressure the bottle can burst; below it the mousse is weak. That’s why the Comité Champagne enforces strict norms for added sugar quantities.
In other sparkling wine regions less sugar is sometimes added to get lower pressure. Crémant d’Alsace typically uses 22 g/l (~5.5 bars), Franciacorta sometimes 20 g/l (~5 bars). Lower pressure = softer mousse = different mouthfeel.
In practice
For the drinker the prise de mousse isn’t directly observable. What you taste is the result: fine mousse, persistent bubbles, a specific mouthfeel. But on a tour at a Champagne house you can see the bottle during prise de mousse: lying on its side, crown cap pointing up, in rows of hundreds or thousands.
Best time to observe the step: August through November, when many houses bottle their new harvest for the prise de mousse. Visits in those months give the most concrete view of the process.
Frequently asked questions
How long does the prise de mousse take?
6 to 8 weeks at 10-12°C. Sometimes slightly longer in colder cellars, shorter in warmer ones. After that the yeast stops and lees ageing (autolysis) begins, which takes months to years.
Does prise de mousse differ between Champagne and Crémant?
Technically identical, often different in duration and pressure. The Comité Champagne uses 24 g/l sugar addition (6 bars). Crémant AOCs vary between 20-22 g/l (5-5.5 bars). The difference lies mainly in mousse fineness: higher pressure = finer bubbles, when properly managed.
What is liqueur de tirage?
The mixture of wine, sugar and yeast added to the base wine to start the prise de mousse. See liqueur de tirage for explanation of yeast strains and composition.