The Second Fermentation

The bubbles in Prosecco almost always arise in a pressure tank rather than in the bottle. The method is called Metodo Martinotti in Italy, named after Federico Martinotti from Asti, who had it patented in 1895. Eugène Charmat improved it in 1907, which is why it's usually called the Charmat method outside Italy. The still base wine is given sugar and yeast, pumped into a sealed stainless steel tank, and ferments there a second time.

The carbon dioxide can't escape and dissolves into the wine. In Spumante, the sparkling-wine style of the DOC, the law requires at least 3.5 bar of pressure, more than in a typical car tire. How long fermentation takes depends on the house, from a few weeks to several months. For Rosé, the DOC prescribes at least 60 days.

Frizzante is the lighter line: semi-sparkling wine with 1 to 2.5 bar. It barely foams, lightly fizzes in the glass, and in Italy often carries a string around the cork, the spago. This also has to do with tax law. According to common practice, Frizzante under 3 bar doesn't count as sparkling wine under Germany's sparkling wine tax, as long as the bottle isn't sealed with a sparkling-wine stopper with a retaining cage. That's one of the reasons for the string instead of the wire cage.

By comparison: the sparkling wine tax is a fixed amount per hectoliter, namely 136 euros, which comes to a good 100 cents per 0.75-liter bottle. With millions of bottles, that matters to every seller. It has nothing to do with the quality of the wine, only with its legal classification.

Whether Spumante or Frizzante, the idea is the same: the wine stays cool and is quickly separated from the remaining yeast after fermentation. This protects the fruit and keeps production predictable. Bottle fermentation remains the exception for Prosecco; the bulk of it comes from stainless steel.