There are four ways to make sparkling wine, each of which produces a very different wine. It’s important to remember that all sparkling wines still wines that have undergone some additional processes that add bubbles. To make a decent sparkling wine, the original still wine also needs to be of high quality.
The traditional or classic method is used to make Champagne and is sometimes known as the Champagne method. The bubbles form as a part of the secondary fermentation (that for ordinary wine usually takes place in large steel vats or barrels) and this takes place in the bottle that the wine will be sold in. This secondary fermentation is started by the addition of ‘Liquer de Tirage’ to the still wine, this is a cocktail of wine, sugar, yeasts and a clarifying agent. The fermentation produces CO2 and thus the bubbles. This method is quite lengthy and involved which accounts for the high cost of Champagne.
The transfer or transversage method is similar to the traditional method, but the secondary fermentation doesn’t take place in the bottle the wine is released in. The fermentation takes place in larger bottles and is then transferred to smaller bottles for sale. This method should result in a more consistent end product, as more wine undergoes exactly the same process, but the quality of bubbles is affected and isn’t as fine as with the traditional method.
The tank or Charmat method works on the same principal as the transfer method, just on a larger scale – the secondary fermentation takes place in large tanks. Again it produces a wine with a consistent quality but the bubbles are affected to even a greater degree.
Carbon injection or carbonation is the cheapest and lowest quality procedure. CO2 is pumped into the wine, just like a soda stream. This process is rarely used, cannot label itself a quality wine and produces a sparkling wine with large aggressive bubbles that is not pleasant to drink.