What is Champagne?
Champagne is a sparkling wine produced as a result of a secondary fermentation which takes place in the bottle producing carbon dioxide which stays in the wine. Today, many sparkling wines are made this way but to be labelled "Champagne", it must be produced within the region of northern France which bears the name. So-called "Champagne" from other countries is may not be sold as such within the European Union.
How is Champagne made?
Champagne is produced using what is known today as the méthode traditionelle (most other quality sparkling wines also use this method). Grapes are harvested earlier than for still wine paroduction as it is desirable to have lower sugars and high levels of acidity than for most wines. Although red grapes may be used (Pinot Noir and Pinot Meunier) in addition to Chardonnay, most Champagne is white so the skins have to be removed from the equation quickly to prevent discolouration.
The primary fermentation is as for still wines, after which the wine is bottled. This wine is extremely tart and generally unpleasant to drink. Blending takes place (if at all which is not always the case with growers' wines) at this stage. Next, a secondary fermentation is induced in the bottle by the introduction of a solution of yeast and sugar (to give the yeast something to work with) called the liqueur de tirage which will go on to produce the carbon dioxide that makes the fizz The bottle is sealed with a metal cap (like those used on bottles of beer) whilst the secondary fermentation takes place leaving a very dry, sparkling wine.
Following this, the wines are "riddled" (see below) for at least 18 months so that the lees settle on the neck of the wine bottle, from where they can be removed in a process known as "disgorgement" prior to "dosage" (the addition of a further sugar solution to determine the sweetness of the wine) and finally resealed with a special mushroom-shaped cork.
After two fermentations, there is a considerable amount of sediment in the bottle which must be removed (primarily the dead yeast cells which contribute to the flavour of the wine). This is achieved through a two-fold process: remuage and disgorgement. Remuage (or riddling in English) is the process in which bottles are placed, necks pointing down at an angle on special racks called pupitres. Over a six week period, every two to three days, a remuer twists every bottle and replaces it in the pupitre which is further angled towards the vertical until, at last, the bottles are completely upside down. In this way, the sediment gradually works its way towards the neck of the bottle. Today this process has been replaced by machines in all but a few houses.
Once the sediment has collected in the bottle neck, the wine is ready for the final stages. First, dégorgement (disgorging in English) which is the process of removing the unwanted sediment. The bottle is now upside down and vertical; in order to remove the unwanted substances, the neck is frozen so that a plug of frozen matter is created which can then be pulled out of the bottle. An elementary knowledge of physics reminds one that there is a loss of volume which must be replaced, in this case by a "liqueur de expedition" - a mixture of base wine and sugar - known as the dosage. The sugar balances the acidity of the wine and also determines the final sweetness of the wine. A Brut Champagne will only have a little sugar added; Extra Sec a little more followed by Sec, Demi-Sec up to the sweetest level, "Doux". At the other end of the spectrum, some have no sugar added at all and are called (unsurprisingly) "Zéro dosage". After all this, the bottle is resealed with the well-known mushroom cork and foil.
What makes it Champagne?
As mentioned above, to be entitled to the label "Champagne" the wine must come from the eponymous region in northern France. There are three sub-zones: the Montagne de Reims in the north which is predominantly Pinot Meunier country; the central Vallée da la Marne where Pinot Noir is king, and the Côtes des Blancs in the south which, as the name suggests, is planted predominantly with Chardonnay (although, in fact, some red grapes can be found). Lastly, the Aube is entitled to appellation status but produces wines widely considered to be inferior.
Some areas have within them demarcated zones of Premier and Grand Cru status. Probably the very finest Champagnes hail from the Côtes des Blancs from Premier and Grand Cru areas such as Mesnil and Vertus (see Michel Rocourt!)