Sparkling wine is an alcoholic beverage made from partially fermented grape must, through a wine base obtained from different grape varieties of Vitis vinifera genus that would later on have a second alcoholic fermentation in bottle to obtain the carbonic gas or sparkle.
Main varieties used for sparkling wine production are: Macabeo, Xarel.lo, Parellada and Trepat within the Cava appellation, and Chardonnay, Pinot Noir and Pinot Meunier in Champagne. Keep in mind that both Cava and Champagne are the most renowned worldwide producers of sparkling wine; however there are other producing regions such as Sekt, Prosseco and Crémant.
How is sparkling wine obtained?
There are different methods to bring forth a sparkling wine: champenoise method, also known as traditional or classic one, where the second fermentation is produced in the bottle after yeasts addition; transfer method, where the second fermentation is produced in the bottle but later the liquid is racked into a deposit to filter it and then put in the bottle again to be distributed; Granvás or Charmat method, where the second fermentation takes place in big gas-tight vats; and finally the gasification method, where carbonic gas is added to base wine.
Doubtlessly, champenoise method is the most expensive one but it is also the one which supplies the best sparkle quality and consequently the best final product.
The first step to produce any sparkling wine is to obtain a base of white wine with low alcoholic degree and smooth astringency that has followed white winemaking standard procedures. There are some producers who keep aside a small quantity of white wine to be aged in oak in order to furnish tertiary ageing aroma to the wine, for instance some cuvées by Krug and Castell de Sant Antoni.
Once the wine is in big stainless steel deposits, the expedition or tirage liquor is added. This liquor is made of sugar and saccharomyces bayanus yeasts. Then, the mix is bottled in glass and corked with a cap similar to the one used for beer and a shutter. The glass is distinguishable for its thickness, as it has to endure the second fermentation pressure, which can reach up to 6 atmospheres.
The next step is the horizontal storage of the bottles, called rhyme, in the cellar with constant humidity and temperature. Rhyme ageing takes at least 9 months for Cava and 15 months for Champagne. During this phase, yeasts thrives on sugar and release both alcohol and carbonic gas (CO2), causing the cherished sparkle. After the second fermentation, yeasts die from asphyxiation and remain sedimented in the bottle; these are the famous lees that give the typical autolysis bouquet to wine.
Once rhyme ageing is finished (from 9 to 60 months, depending on the cuvée) is the moment for clearing or fining, by turning regularly the bottles now placed on desks, until they get in vertical position, thus transferring the lees to the bottleneck.
It is time for disgorgement, freezing the bottleneck with a champagel equipment. Then bottles are uncorked, so as to eliminate the part of the freeze wine that has yeasts sediments, a diminishment that is completed with base wine, if the idea is to obtain a brut nature, or with expedition liquor to obtain an extra brut sparkling wine (up to 6 g/l sugar), brut (up to 15 g/l), extra sec (from 12 to 20 g/l), sec (from 17 to 32 g/l), semi sec (from 33 to 50 g/l) or sweet (over 50 g/l). Expedition liquor is a blend of sugar and aged white wine.
Now all that's missing is corking, labelling and distribution. Bubbles party!