How does wine get its bubbles? The methods of making sparkling wine
The common feature of sparkling wines is that the wine ferments in a closed space under pressure, and the carbon dioxide formed in the process stays dissolved in it. That is what gives it its sparkling bubbles. In most methods this is a second, so-called secondary fermentation; in pét-nat and Asti it is the continuation of the same fermentation. The main difference is whether the fermentation takes place in the bottle or in a tank.
What do the two routes give?
The bottle method gives fine bubbles and brioche and bread-crust aromas. The tank method is faster and cheaper, and preserves the grape's fruit and floral aromas.
The five methods in brief
- Traditional method (méthode traditionnelle): secondary fermentation and maturing take place in the bottle, followed at the end by riddling, disgorgement and dosage.
- Transfer method: fermentation in the bottle, but at the end the contents of the bottle are emptied into a tank.
- Charmat (tank) method: secondary fermentation takes place in a pressure tank.
- Ancestral method (pét-nat): the base wine is bottled before the end of the first fermentation.
- Asti method: a single fermentation in a tank, which the winemaker stops, so that a sweet wine with little alcohol results.