How is sparkling wine processed?

Wines which are not still, those which contain a high level of carbon dioxide, are called sparkling wine. 

Sparkling wine requires unique processing, at least in the secondary fermentation that occurs in the bottles or in tanks under pressure (Charmat process).

Sparkling wines are relatively expensive, owing to high taxation as well as processing cost. High quality cannot be attained without care in the selection of the table wine to be champagnized.

There are four methods of producing sparkling wine are: Charmat or Cuvee Close, Transversage, Carbonation and methode champenoise. They all aim to produce a clear wine containing bubbles of carbon dioxide.

Many sparkling wines are made by the method champenoise, which is the traditional method of making champagne.

All wine goes through a fermentation process that turns the grape juice into an alcoholic beverage. During this fermentation, yeast cells transform sugar into ethyl alcohol, they produce carbon dioxide gas. The carbon dioxide is allowed to dissipate in the first fermentation.

After the wine has gone through primary fermentation the wine is ready to be bottled and go through the second alcoholic bottle fermentation which can be a manual or automated system.

There is a secondary fermentation after the wine is bottled and capped. This time carbon dioxide remains trapped in the bottle, that’s why there are bubbles in champagne. Complete fermentation and pressure generation are slow and usually take several weeks.

The yeast cells must flocculate and settle efficiently once the secondary fermentation is completed. The sediment begins to form in the wine, in a process known as autolysis.

In order to produce a crystal clear sparkling wine, the remaining dead yeast must be quickly removed and this technique known as the ‘Champagne method’ and often appears on wine labels as ‘methode champenoise’.

The yeast is ready to be removed by disgorging. The bottles are chilled to just above the freezing point and placed upside down in a brine bath to freeze the wine in the neck of the bottle.

This traps the yeast, and when the crown cap is removed, the pressure of the wine expels the plug of frozen wine, taking the yeast with it.

The sparkling wines attain their full maturity in the third year after being bottled and will lose nothing of their sparkling quality within a dozen year.
How is sparkling wine processed?