Méthode Champenoise is the traditional method by which Champagne is produced. After primary fermentation and bottling, a second alcoholic fermentation occurs in the bottle. This second fermentation is induced by adding several grams of yeast (usually Saccharomyces cerevisiae, although each brand has its own secret recipe) and several grams of rock sugar. According to the Appellation d’Origine Contrôlée a minimum of 1.5 years is required to completely develop all the flavour. For years where the harvest is exceptional, a millesimé is declared and some Champagne will be made from and labelled as the products of a single vintage rather than a blend of multiple years’ harvests. This means that the Champagne will be very good and has to mature for at least 3 years. During this time the Champagne bottle is sealed with a crown cap similar to that used on beer bottles.
After aging, the bottle is manipulated, either manually or mechanically, in a process called remuage, so that the lees settle in the neck of the bottle. After chilling the bottles, the neck is frozen, and the cap removed. The pressure in the bottle forces out the ice containing the lees, and the bottle is quickly corked to maintain the carbon dioxide in solution. Some syrup (le dosage) is added to maintain the level within the bottle and, importantly, adjust the sweetness of the finished wine.
An initial burst of effervescence occurs when the Champagne contacts the dry glass on pouring. These bubbles form on imperfections in the glass that facilitate nucleation or, to a lesser extent, on cellulose fibres left over from the wiping/drying process as shown with a high-speed video camera. However, after the initial rush, these naturally occurring imperfections are typically too small to consistently act as nucleation points as the surface tension of the liquid smoothes out these minute irregularities. The nucleation sites that act as a source for the ongoing effervescence are not natural imperfections in the glass, but actually occur where the glass has been etched by the manufacturer or the customer. This etching is typically done with acid, a laser, or a glass etching tool from a craft shop to provide nucleation sites for continuous bubble formation (note that not all glasses are etched in this way). In 1662, this method was developed by the British, as records from the Royal Society show.
Dom Pérignon was originally charged by his superiors at the Abbey of Hautvillers to get rid of the bubbles since the pressure in the bottles caused many of them to burst in the cellar. As sparkling wine production increased in the early 18th century, cellar workers had to wear heavy iron mask that resembled a baseball catcher’s mask to prevent injury from spontaneously bursting bottles. The disturbance caused by one bottle’s disintegration could cause a chain reaction, with it being routine for cellars to lose 20–90% of their bottles to instability. The mysterious circumstance surrounding the then unknown process of fermentation and carbonic gas caused some critics to call the sparkling creations “The Devil’s Wine”.
There are more than one hundred Champagne houses and 19,000 smaller vignerons (vine-growing producers) in Champagne. These companies manage some 32,000 hectares of vineyards in the region. The type of Champagne producer can be identified from the abbreviations followed by the official number on the bottle: