Partial Fermentation (Moscato)
This is an alteration from the Charmat method, and does not allow for a full fermentation of the base wine. This allows for a sweeter, carbonated wine to be made without fully completing the first alcoholic fermentation in either fermentation step.
In the first fermentation, the wine is only fermented up to about 6% alcohol, rapidly chilled, racked and kept cool. Once the wine is transferred, the base wine will be warmed up in a pressurized tank to allow for more alcohol production, but with retention of residual sugar. Once completed, the wine is sterile filtered and bottled. Examples of commercial wines that utilize the partial fermentation method include Moscato d’Asti and Brachetto d’Acqui (Brachetto) from Italy, although many commercial wines around the world utilize parts of this process to retain residual sugar and light carbonation in the final product.