A distinction must be made between deliberate secondary fermentation in the bottle in the production of quality sparkling wine and undesirable secondary fermentation in the case of a still wine:
By adding the dosage (Fülldosage = sugar and yeast) to the bottle, a second fermentation is initiated for the base wine. During the second alcoholic fermentation of this wine, the sugar is converted, transformed into alcohol and carbonic acid, which increases the carbonic acid pressure in this bottle enormously. In addition, further esters and higher quality alcohols are produced, which have a positive influence on the taste of the wine. A bottle fermentation is legally obligatory for a champagne, but for other sparkling wines the second fermentation can also be done in the tank by means of Méthode charmat. Bottled fermented sparkling wines are declared on the label by means of EU standardised designations. These are Méthode champenoise (only for champagne), or Méthode classique (also Méthode traditionnelle), which is also permitted in the national language. In the absence of a label, it can be assumed that the sparkling wine was not produced according to the traditional method.