Wine Basics - Sparkling Wine
All sparkling wines start life as still wines and have the sparkle added later. The crucial factor in the quality of every sparkling wine is how the fizz is added. The fermentation process naturally produces carbon dioxide gas (CO2)- the waste product of the yeasts devouring the sugars. In still winemaking this gas is allowed to escape. In sparkling wines, the CO2 is retained, dissolving within the wine which is kept under pressure. When it is released, the CO2 bubbles to the surface. The method for producing a wine filled with CO2 varies from the very time-consuming and expensive Champagne method of natural, secondary fermentation in individual bottles, to the inexpensive and easy method of squirting industrial CO2 into cheap, still wine.
The Champagne method
The Champenois are justifiably proud of their wines and the age-old methods used in their creation. Legend has it that the method was invented by a monk and winemaker named Dom Pérignon. Champagne itself can come only from a very well defined area in the northeast of France, but many quality wines are made using the "Méthode Champenoise" (this term is no longer allowed on labels, so the term "traditional method" is often used instead).
First of all, a high-quality, dry white wine is made (usually from a blend of chardonnay, pinot noir and pinot meunier grapes) with "ordinary" tank fermentation. Once the wine is complete it is placed into special, heavyweight bottles and a fresh dose of yeast and sugar is added. The bottles are then capped and placed in the cool cellars of the winery for up to 2 years. During this time, a secondary fermentation takes place. The yeasts and sugars create CO2 that, because it is in a sealed container, cannot escape, so dissolves into the liquid. In the early days Champagne production was a dangerous business- cellars were destroyed by exploding wines. Controlled production methods and stronger bottles have eliminated that risk. The problem with this technique is the deposit of dead yeast cells that collects in the bottle. In still wines these would simply be filtered out, but since that would also remove the bubbles, another method had to be found. This process is known as Remuage: an action whereby each bottle is shaken lightly, revolved and its position adjusted, so that over the course of a few weeks the bottle ends up upside-down with the dead yeast cells captured in the neck of the bottle.
The Remueur can precisely adjust 40,000 bottles per day. At this stage the inverted bottles are carefully transported to a freezing tank. The necks are dipped in, just to the level of the gathered sediment, which freezes into a solid "plug" of dead yeast cells. The caps are removed and the gas pressure shoots the plug out. Depending on the style of wine being made (dry, medium or sweet) the bottles are topped up with a "dosage" of reserved wine and sugar.
The bottles are corked, wired, and at that stage, the Champagne is complete. Though this process is long, expensive and labour-intensive, no other method produces wines with such fine and persistent bubbles and such a creamy complexity on the tongue.
The tank method
This is a different process by which good quality bubblies can be made. Here the secondary fermentation still takes place naturally, by adding new yeast and sugar to a finished wine, but instead of taking place in bottles, the wine is held under pressure in large, sealed tanks so that the equivalent of several thousand bottles re-ferment at the same time. The wine is cleared of sediment and bottled under pressure, directly from the tank. The bubbles are a little larger and disperse more quickly, but the tank method can produce good results.
The transfer method
This is a less common system for creating a sparkling wine. Here, secondary fermentation takes place in individual bottles- like Champagne- but instead of the expensive remuage process, the wine is cleared by filtration and is then pumped, under pressure, into clean bottles.
Sparkling wine tastes and styles
Champagne/Sparkling wines can be made white or rosé. Although rare, there are examples of red sparkling wines, such as the deep red, sparkling syrah from Australia. Most Champagnes tend towards a dry, elegant style, but many other sparkling wines (such as Asti-Spumanti for example) are lighter in alcohol and sweet, or semi-sweet.