How do they make Champagne Bubbly?

Have you ever stopped and wondered how Champagne gets (and keeps) its bubbles? Most people assume that it is produced by using the same technique as used for making soft drink - An injection of carbon dioxide bubbles into a still wine.

In reality, sparkling wine is traditionally made via three sometimes laborious methods, with a sliding scale of effort suitably matched to the intended final style (and price) - Only very cheap 'passion pop' styled bubblies are produced by the aforementioned carbon dioxide injection. The CO2 injection method is used as it is the simplest & cheapest, but produces large, coarse bubbles that dissipate quickly in the glass.

The second method is known as the 'charmat' or tank method and is most commonly used for the production of fruity sparkling wines where freshness is the key (such as the Italian sparkling Prosecco). This process involves a secondary fermentation that takes place in a pressurised stainless steel tank. The resultant bubbles (called the bead) are smaller and finer than the injection method but nowhere near as constant or long lasting as those bubblies produced using the bottle fermentation method below.

The final method is known as the traditional method (or Methode Champenoise) which French Champagne and most premium sparkling wines are produced by. This lengthy, labour intensive process involves a secondary fermentation in bottle and maturation process that can last up to 10 yrs for some super premium Champagne, producing the highest quality sparkling wines with the finest, most persistent bead.

Step by Step Sparkling Wine Production

1 In the vineyard
As the proverb says, great wine is made in the vineyard: Sparkling wine is no exception. Most grapes used in the production of sparkling wine are picked earlier than their still counterparts (except for sparkling red, but that is a whole other story) with the aim to retain high levels of natural grape acidity and create a refreshing sparkling wine.

If we are creating a traditional French Champagne style sparkling there are only three grape varieties that are used: Pinot Noir, Chardonnay & Pinot Meunier. However sparkling wine can be made from just about anything - From Sauvignon Blanc to Durif to Chambourcin.

Picking for sparkling wine is often done by hand and at night time to minimise oxidation & preserve the inherent crisp freshness. In Champagne this is taken to the next level wit press houses located in amongst the vines to attempt to get the graps in and crushed as soon as possible.

2. Making the Base Wine
Once in the winery the grapes are crushed and fermented like any other still wine with the yeast (natural or added) converting grape sugars into alcohol. Once this still wine is produced it can be blended with different base wines from different vineyards (or different years) to form a master blend - known as a cuvée. At this stage the base wine may simply be injected with carbon dioxide and bottled immediately if a low budget sparkling wine is the aim, or follow on to the steps below for higher quality examples.

3.Secondary Fermentation
After this the base cuvée has a mixture of yeast and sugar added which serves to start a secondary fermentation process - creating bubbles of carbon dioxide, which are gradually integrated into the wine over a period of time (making for smaller, finer & more persistent bubbles). This second ferment can take place in a tank (Charmat method) or will take place in the individual bottle (Traditional method).
With the Charmat method, the sparkling wine is bottled quite quickly (3 weeks to 3 months) after this secondary fermentation to aid in freshness (albeit with less bottle pressure and less persistent bubbles). If we are using the traditional method the bottle is then sealed with a crown seal and sent off for maturation on lees.

4.Ageing on Yeast Lees
The next stage in the sparkling production process can take the most time, but is the most crucial in the production of complex, premium bubbly. Once the yeast cells used in the second ferment run out of sugar to feed on, they simply starve and die in the bottle. However, their usefulness does not stop there, with the wine drawing more flavour out of the dead yeast cells (known as yeast lees) the longer they are in contact. This process is known as yeast autolysis - a poorly understood chemical process that serves to give top Champagne the lovely bready, creamy, yeast derived flavour that it is renowned for. Ageing on yeast lees is compulsory for French Champagne (15 months minimum) and can last for a decade plus in the finest vintage wines.

5.Riddling
Once the wine has spent its requisite time ageing on its yeast lees, we need to remove the lees from the bottle (or end up with cloudy sparkling). This was traditionally done over a six week period by hand, with the bottles gradually turned from a horizontal position to inverted vertical by human 'riddlers' - using a special wooden riddling rack called a 'pupitre' (Like those in the photo above). These days the task is covered by a 'gyropalette' which looks like a massive wine carton, mechanically inverting the bottles and then vigorously shaking the contents - Forcing the yeast lees down into the neck of the bottle.

6.Disgorgement and bottling
The final step in this complex process is delightfully dramatic. The yeast lees now lie in the top of the bottle and we just have to get them out! This is done by dunking the neck of the bottle in a freezing solution, which freezes the bottle neck and the yeast lees with it. The bottles are then upended & opened, with the lees deposit jettisoned out by the pressure contained in the bottle, taking the form of a flying frozen yeast pellet! The bottle is then topped up with a mixture of wine and sugar syrup known as the 'dosage'. The sweetness of the dosage can vary from nil (in Brut Nature or ZD wines for example) up to about 12g/l, depending upon the desired finished style.

The bottle is finally then sealed with a special sparkling cork (Champagne producers are said to get the best cork in the world) with a wire muselet cage ensuring that the approximately six atmospheres of pressure doesn't force the cork off.

A few of our favourite Champagnes produced using the Traditional Method