Explaining the Five Stages of the Charmat Method

In previous articles, we have talked about the Metodo Classico (or Traditional Method, also known as Method Champenois). This article introduces another method that is used to make sparkling wines: the Charmat Method.

While the traditional method is labour-intensive and requires the producer to dedicate a lot of time and resources to their winemaking, the Charmat method is a bit quicker. It is widely used in Italy and internationally by producers such as those who make Prosecco and Asti Spumante.

Also called the Marinotti method or the tank method, the Charmat method was invented in 1895 by an Italian winemaker named Federico Martinotti. However, 12 years later, a French producer named Eugene Charmat tweaked Martinotti’s original method, creating the Charmat method that we know today.

The Charmat Method is more efficient than the traditional method. It allows for the secondary fermentation of large quantities of wine inside large tanks, rather than the traditional method’s reliance on fermentation within the bottle. But that’s not the only difference between the traditional and the Charmat method. The latter actually incorporates a five-stage process that we will explain in this article.

Stage #1 – Primary Fermentation

After the grapes have been picked and all of their juices are extracted, the wine is placed into large stainless steel vats. Here, it undergoes a primary fermentation process that results in a still white Italian wine that has a fairly low alcohol percentage and a fruitier taste than the final sparkling product will have.

You can think of this initial wine as the base of the sparkling wine to come. It’s actually an edible drink in its own right. However, it doesn’t yet have the qualities that a sparkling wine needs to have. What’s more, it may not be strong enough to be sold as a still white wine.

Stage #2 – Secondary Fermentation

It’s here where we see the main difference between the Charmat method and the traditional one.

In the traditional method, the original wine is poured into the bottle in which it will be sold. That bottle then receives a temporary cap and the producer leaves it until the yeast finishes working and dies.

The Charmat method differs because the original wine mixture does not go in the bottle. Instead, it’s placed in vast stainless steel tanks, which is where the method gets its alternative name of the “tank method”.

This tank is called an autoclave. After the wine is added, the producer mixes in sugar and yeast to create a chemical reaction that induces the original wine. The resulting mixture is called the wine’s tirage.

Depending on the wine, this secondary fermentation process can take anywhere between three months and a year. Over that time, bubbles will start to appear in the wine, with the process continuing until the yeast dies and becomes a substance called lees.

Stage #3 – Cooling and Filtering

Once secondary fermentation is completed, the wine has the bubbles you’d expect it to have as a sparkling wine.

But the process isn’t done yet.

There’s still the small problem of a huge tank of wine that also contains a lot of dead yeast cells. The lees are not something that any consumer will want to drink, which means they need to be filtered out of the wine before it can be bottled.

The problem is that the wine will still be undergoing a fermentation process, even after the death of the yeast cells. So, it needs to be cooled before it can be filtered. The producer uses machinery to create a cooling effect, which takes advantage of stainless steel’s ability to transmit cold as well as to conduct heat. Once the wine is cool enough to stop the fermentation process, it’s run through an enormous filter while it is transferred from one tank to another.

Stage #4 – Adding Sugar

While we’ve marked this as the fourth stage of the Charmat method, the reality is that producers can add sugar at almost any point of the process.

The amount of sugar added is called the dosage and it determines how sweet the wine will be. If the producer wishes to make a dry wine, such as a Prosecco, they’ll use less sugar than they’d use to create a sweeter wine. The presence of sugar also influences the wine’s alcohol volume. As a very general rule, more sugar usually means that the wine emerges with a higher alcohol content. However, this isn’t a hard and fast rule.

Stage #5 – Bottling the Wine

Once the fermentation and filtering processes are completed, all that’s left is to bottle the wine ready for shipping.

Except that process isn’t as simple as it would seem.

When bottling a still Italian wine, the producer doesn’t need to worry too much about the pressure inside the bottle. They need to create a seal to prevent oxygen from getting inside. But beyond that, pressure isn’t a major concern. But with sparkling wines, maintaining pressure is key to ensure the bubbles are as powerful when the bottle is opened as they were when the wine was fermenting. As such, the producer has to keep the bottle under pressure until it’s sealed to ensure the bubbles are still there when you open it.

Once that’s done, the wine is packaged, sold, and shipped to wherever it needs to go.

The Final Word

There’s some debate over whether the traditional or Charmat method is the best choice for creating sparkling Italian wine.

In our opinion, they’re both capable of creating some stunning wines. While it’s true that Champagne is the result of the traditional method, the Charmat method gives us Prosecco, which is the most popular sparkling wine in the world. That alone tells us that there are plenty of merits to the Charmat method. And ultimately, the only major difference between the two is that the Charmat method is more efficient, which allows for greater quantities of sparkling wine to be produced using it.

With that being said, perhaps now is the time to sample an Italian wine or two made using the Charmat method. You’ll find plenty of examples if you explore the Xtrawine collection.