The Science Behind Bubbles: CO₂, Pressure & Perlage Explained
There’s a certain undeniable luxury behind sparkling wines. Whether down to their aromatic complexity or spritzy mouthfeel, they’ve cemented themselves as the quintessential celebratory tipple.
One of the fascinating things about them is the bubbles themselves. This delicate string of pearls rising from the base of the glass, literally “perlage”, can have a long and complicated creation process, striking a fine balance between physics and patience.
The Pressure Behind The Pour
Still wines are a finished story, but sparkling wine has a further chapter.
Most bottles undergo a secondary fermentation. After the initial wine is crafted, a small amount of sugar and yeast is added back into the mix. If this happens in a sealed bottle - the famed méthode traditionelle - the resulting carbon dioxide has nowhere to go. Under pressure, the gas dissolves into the wine itself, waiting for the moment the cork is eased away.
The pressure inside that bottle is roughly double what you’d find in a car tire. This is why Champagne bottles tend to have thicker glass – before this, they would historically explode in cellars with the pressure!
When that pressure is finally released, the dissolved CO₂ looks for a way out, and the "sparkle" is born.
Texture, Time, And The "Mousse"
We often talk about the "mousse" of a wine - the tactile, creamy foam that forms when it hits the palate. The texture of that mousse changes depending on how the wine was made.
In wines aged for a long time on their "lees" (spent yeast cells), the bubbles tend to be smaller and more integrated, known as “fine perlage”. The yeast cells break down and release proteins, which act like tiny life jackets for the CO₂ bubbles, coating them and preventing them from merging into larger bubbles. These tiny, persistent beads create a silkier, more velvet-like mouthfeel.
On the other hand, wines made with the "Charmat method" in metal tanks - like many of our favourite Proseccos - often have larger, more energetic bubbles. These are bright, frothy, and wonderfully lively, designed to emphasize the fresh, floral fruit of the grape.
The Aromas
The bubbles do more than just provide texture; they are the wine’s aromatic delivery system. As each bubble rises, it collects fragrant compounds along the way. When it reaches the surface and eventually bursts, it releases a microscopic mist of aroma.
This is why the scent of a sparkling wine is so immediate. It’s a literal lift of fragrance—sending notes of toasted bread, white flowers, or citrus zest directly to the senses. The finer the perlage, the more consistent that delivery becomes, allowing the wine to reveal its layers slowly as it sits in the glass.
A Note On The Glass
If you ever find your wine appears to be still, don't worry - it isn't flat. This is often a sign of a perfectly polished glass. Bubbles need a "nucleation point," a tiny imperfection or a microscopic fibre, to begin their climb. Some of our favourite glassware is even laser-etched at the base specifically to give the bubbles a place to start their journey.
So, the next time you pull a cork, take a second to watch the climb. There’s an entire world of physics rising to the surface.
Find Your Favourite Style
The best way to understand these differences is to taste them side-by-side. From the soft creaminess of a traditional method wine to the bright lift of a tank-fermented bottle, every pour has its own personality.