How is sparkling wine made?

I am pretty sure you like bubbly wines just as much as I do! But sometimes you wonder how sparkling wine is made and how these fine bubbles are trapped in the bottle. Maybe when someone starts talking about the methods used to produce sparkling wine, they use words that you don’t really understand.

Then don’t worry, I am here to help you understand these terms and the whole process behind the preparation of Champagne, Prosecco, Cava and other sparkling wines. I won’t go too deep into every technical detail in this article, but if you are interested in knowing more, just reach out to me and I will be happy to share the rest!

How are the bubbles created in sparkling wine?

First of all, we have to stress that there isn’t just one way to make sparkling wine. In many of the most important production methods, the bubbles are created during a second fermentation. The first fermentation is when the still base wine is made, while the second fermentation creates the carbon dioxide that gives sparkling wine its characteristic bubbles.

There are several important methods used around the world:

• Traditional Method — used for Champagne, Cava, Crémant and Franciacorta, and Sekt, among others
• Tank Method or Charmat Method — famously used for Prosecco and also some Lambrusco
• Transfer Method — used for some small-format and large-format traditional-method sparkling wines
• Ancestral Method — used for styles such as Pét-Nat and some sparkling wines from the Loire Valley and Jura

With these methods, the second fermentation takes place either in the bottle or in a pressurised tank. Yeast and sugar are added to start the fermentation, and during this process the alcohol level increases as well.

The Traditional Method: how Champagne is made

The main exception among these methods is the Tank Method, where the second fermentation takes place in a temperature-controlled tank rather than in the bottle. Once fermentation is complete, the sparkling wine is filtered to remove the dead yeast and is then bottled with the appropriate amount of sugar and wine.

But let’s move back to second fermentation in the bottle.

The most important aspect of the Traditional Method is that the transformation from still wine into sparkling wine occurs entirely inside the bottle. This is the method used to produce Champagne and several other high-quality traditional-method sparkling wines.

During the Traditional Method, we can also become familiar with some specific terms used in sparkling wine production.

Base wine or “Cuvée”

Grapes are picked, usually a little earlier to preserve acidity, and fermented into a dry base wine. This wine generally has a lower alcohol level because the second fermentation will increase it further.

The winemaker then takes the different base wines and blends them together to create the final cuvée.

Tirage

Tirage is the addition of yeast and sugar to the cuvée to start the second fermentation.

Second fermentation

During the second fermentation, the wine gains around 1.3% more alcohol and produces carbon dioxide (CO₂). Because the bottle is sealed, the CO₂ dissolves into the wine and creates the bubbles.

The yeast eventually dies and remains in the bottle, where it begins a process known as autolysis.

Ageing on the lees

The wine is aged on its lees, meaning the dead yeast cells left behind after fermentation. This period allows the wine to develop additional texture and complex flavours.

Generally, the longer a sparkling wine spends ageing on its lees, the more developed and complex its character can become.

Riddling

During riddling, the bottles are gradually moved into an inverted position so that the dead yeast cells collect in the neck of the bottle.

Disgorgement

Disgorgement removes the sediment from the bottle. The bottles are placed upside down into a freezing liquid, which freezes the yeast sediment collected in the neck.

The crown cap is then removed momentarily, allowing the frozen plug of lees to shoot out of the pressurised bottle.

Dosage

Finally, a mixture of wine and sugar called the dosage is added to fill the bottle. The bottle is then corked, wired and labelled.

The Transfer Method

With the Transfer Method, the sparkling wine goes through its second fermentation and lees ageing in the bottle, much like the Traditional Method.

After ageing, however, the wine is transferred into pressurised tanks, where it is filtered and the dead yeast is removed. The wine is then returned to bottles and receives its final dosage.

The Ancestral Method

The Ancestral Method works differently. Fermentation begins in the tank and is interrupted by chilling the wine before it is complete. The partially fermented wine is then bottled, allowing fermentation to continue inside the bottle.

The remaining fermentation produces CO₂, which becomes naturally trapped in the bottle. Depending on the style and producer, the wine may later be chilled, riddled and disgorged. Unlike the Traditional Method, dosage is generally not added.

The Asti Method: sparkling wine with one fermentation

We have now covered the main sparkling wine production methods involving a second fermentation, but there is one important method that uses only one fermentation: the Asti Method.

So, how is sparkling wine made with the Asti Method?

The must is chilled so fermentation does not begin and is stored until needed. It is then warmed and fermentation starts when the producer is ready to make the wine.

Initially, carbon dioxide is allowed to escape. Partway through fermentation, the tank is sealed to retain the CO₂. Fermentation is then stopped early by chilling the wine, usually when it reaches around 7–7.5% alcohol.

The result is a naturally sweet sparkling wine because some unfermented sugar remains. The wine is then filtered and bottled.

This method is mainly used in Piedmont, Italy, for the production of Moscato d’Asti, but we can also find sweeter styles of sparkling wine made using related techniques in other parts of the world.

How sparkling wine is made: the key methods to remember

As you can see, there is much more than one way of making sparkling wine. The Traditional Method, Tank or Charmat Method, Transfer Method, Ancestral Method and Asti Method all create sparkling wines with different characteristics.

Once you understand the basic production methods and terms such as tirage, lees ageing, riddling, disgorgement and dosage, it becomes much easier to understand what is happening inside that bottle of bubbles in your glass.

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