Have you ever wondered how the sparkle gets put into sparkling wine? How did those little bubbles of carbon dioxide gas get there? Well, there are 3 main methods.
The first and crudest is to simply inject the still wine with bottled CO2 Ð it works, but the sparkle is short lived and not very effective.
The second method goes under a variety of names Ð Tank Method, Charmat Method, Cuve Close Ð here the still wine is put into pressure tanks. Yeast and sugar is introduced into the base wine and the tank is sealed. The yeast reacts with the sugar to produce, amongst other things, CO2 gas which, as the tank is sealed, cannot escape and is forced into the wine. After a short ageing period the wine is filtered and bottled under pressure to retain the fizz. This method can be very effective and relatively inexpensive to carry out. The best known wine that is nearly always made in this way is Prosecco.
The third method is the most complicated, producing the finest results – the Traditional Method (Methode Traditionelle). It is the only method allowed in the production of Champagne and is used for most other top quality sparkling wines. The Traditional Method means that the wine has been bottle fermented Ð that is the wine goes through the second fermentation (to produce the bubbles) in the bottle that it will be sold in. The base wine is blended and bottled along with a small amount of yeast and unfermented grape juice or sugar (this is known as the liqueur de tirage). The bottles are then sealed with a crown cap and left in cool cellars where, like in the Tank Method, the yeast and sugar react to produce a small amount of additional alcohol (usually less than 1%) and the CO2 gas that, because the bottles are sealed cannot escape and is forced into solution in the wine.
After this second fermentation is complete the bottles are left for anything between a few months to several years depending on the wine to rest sur lie Ð on the lees Ð the dead yeast cells of the second fermentation Ð and it is this ageing sur lie that adds great complexity and depth to the final wine.
The problem is that whilst there is fizz in the wine there are also the lees Ð if they are left the wine will be cloudy. The next two processes to clarify the wine are known as remuage and disgorgement. The bottles are put into large, wooden, easel-shaped racks known as pupitre; initially horizontal over many weeks the bottles are slowly tipped and twisted by exact amounts until they are pointing vertically down. This remuage (riddling) process, by slowly twisting and tipping the bottle by exact amounts, moves the sediments down until they are in the neck of the bottle. Traditionally this was done by hand with a good remueur making up to 40,000 twists and turns a day! Today this process has been almost completely replaced by an automatic mechanical system (gyropalette) that works 24 hours a day.
Once the lees are in the neck they need to be removed (the disgorgement) and this is done by putting the neck into a bath of super chilled brine (-30¡C) that freezes the sediments into a neat little ice cube. This can then be removed by putting the bottle upright, taking off the crown cap and allowing the pressure in the wine to eject the ice pellet and the sediments. The small amount of lost wine is replaced and a sweetening wine (liqueur d’expedition or dosage) sometimes added to adjust the style of the end wine. The champagne cork and wire cage are then applied and after a vigorous shake to incorporate the dosage the bottles are left for an additional ageing period before being made ready for sale.
So when you next open a bottle of Champagne or Methode Traditionelle spare a thought for the years of effort that have gone into producing it!