Unpolished Grape 101: How Does Sparkling Wine Get Its Bubbles?

Have you ever had a glass of sparkling wine and wondered how all those beautiful bubbles got into the bottle anyway? It’s quite an interesting process!

Let’s start with the basics! Grape juice turns into wine when yeast consume the sugar and leave alcohol in its place. This process also creates a gust of Carbon Dioxide (CO2), which usually just evaporates into the air. However, if you prevent the CO2 from escaping, it becomes trapped in the wine and creates the bubbles we see.

So how does CO2 get trapped in the wine? Let’s explore the 3 main ways!

Traditional Method (i.e. Champagne)

The “traditional” method is a process in which a bottle of wine undergoes a second fermentation after it’s been bottled. The wine-maker will add a dose of Liqueur de Tirage to the bottle, a mixture that includes a bit of wine, sugar and nutrients. Once the bottle is sealed shut, the yeast get to work re-fermenting the wine because now there is fresh sugar to consume. But this time, the CO2 remains trapped and creates the bubbles inside the bottle.

The dead yeasts stay in the bottle for a while, creating additional “bready” flavors. Next, the bottles undergo a process that removes the yeast and they are re-sealed tight with a heavy duty cork. The trapped CO2 is what we know as bubbles! This method is used in Champagne, Crémant, Cava, and many more sparkling wines from around the world.

Tank Method (i.e. Proseco)

The “tank” method is similar to the traditional method, except that the process happens in a tank as opposed to inside the wine bottle. The Liqueur de Tirage is added directly to the wine in the tank, which is then sealed shut to trap the CO2. Another difference is that at the end of this process, the dead yeast are removed from the bottom of the tank without allowing them to mingle with the wine for a bit. As a result, the wine is bottled with the bubbles, but without the bready flavors found in Champagne and Cava.

Asti Method (Sweet)

Unlike the traditional and tank processes, there is only one fermentation for the “Asti method. Here, the CO2 is trapped during the initial fermentation, and the bubbles begin to form at the same time the grapes are changing over to alcohol. However, the large amounts of CO2 cause the yeasts to die before all of the sugar is depleted, leaving the wine sweet. The dead yeasts are removed and the wine is bottled.

The next time you drink a glass of sparkling wine, remember how it was made!


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