here are two main methods of making sparkling wine: the champenoise method of bottle fermentation, known as the metodo classico or tradizionale in Italian, and the sealed tank fermentation method, often referred to as metodo charmat. A detailed description of the former starts with the following paragraph, while the latter is the subject of this section's next and last chapter.
Assembling the base wine
White Chardonnay and dark Pinot Nero grapes (as well as Pinot Meunier and sometimes other varieties) are picked before they are fully ripe to retain high acidity. After alcoholic fermentation, the wines are blended by each producer into an individual cuvée, which may include different vintages.
The tirage
The base wine is then put into the same bottle in which it will eventually be sold and the liqueur de tirage - a syrupy solution that includes cane sugar and special strains of yeast - is added.
The refermentation
After being sealed with metal caps, bottles are shaken and stacked horizontally in a cool cellar where the wines undergo a second fermentation. The yeasts gradually transform the sugar into another 1 or 2 degrees of alcohol as carbon dioxide builds up to a pressure of 5-6 atmospheres. This process, known as the presa di spuma in Italian, forms the fine bubbles known as perlage.
