Second Fermentation in Sealed Pressure Tank
Tank Method sparking wines also go through two fermentations. After the first fermentation (usually in tank), the base wines are placed in another sealed pressure tank and a mixture of yeast and sugar is added to induce the second fermentation.
As the tank is sealed, the CO2 produced during the second fermentation cannot escape and is trapped in the wine (i.e. the bubbles). In contrast to traditional method sparkling wines, tank method sparkling wines undergo much less lees contact (autolysis) - though this does not have to be the case, as paddles / agitators can be placed inside the tank to ensure better contact with the lees.
After the second fermentation is complete, the wine is fined and filtered to remove the lees and any other sediment. After this step the dosage (mix of sugar and wine that defines whether a wine is Brut, Demi-Sec or Sec etc.) is added to the tank and the wine is bottled under pressure to preserve the bubbles in the bottle.
Advantages of the Tank Method
The Tank Method is a much less expensive and less time-consuming method of sparkling wine production. And while it is mostly associated wit the production of higher volume sparkling wines, this does not mean that it is for producing inferior or lower quality wines. In fact it is a much better process for making sparkling wines from aromatic grape varieties, such as Prosecco or Asti, where you want to preserve the freshness and intensity of the grapes' aromas, rather than cover them up with autolytic complexity.
Other advantages of the Tank or Cuve Close method include the fact that it allows for economies of scale as well as greater control over the quality consistency of the end-product (as everything occurs in the same tank, rather then individual bottles).
In terms of global sparkling wine production, the tank method is the most used method worldwide.
Mary Gorman-McAdams, MW (Master of Wine), is a New York based wine educator, freelance writer and consultant.
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