Sparkling wine is produced when a secondary fermentation takes place in the wine. For this to happen, yeast is added to the base wine, which converts the residual sugar in the wine into alcohol. Carbonic acid is also released and this remains contained in the wine, producing the fine bubbles that give sparkling wine its character.
The sparkling wine must be aged on the lees for a minimum of nine months, for Crémant this is set at twelve months. To remove the lees from the natural sparkling wine, the bottles are riddled in special riddle racks. This allows the lees, which have previously settled on the wall of the lying bottle, to move into the bottle neck. To remove the sediment, the neck of the bottle is frozen. When the crown cork is removed, the ice plug containing the sediment is ejected due to the pressure of the carbonic acid in the bottle. This process is called disgorgement. The dosage that follows, i.e. the addition of a sweet wine to replace the liquid lost during disgorgement, serves to define the flavour of the finished sparkling wine.