How are champagne bubbles formed?

They are the very symbol of champagne, these small, fine and sparkling bubbles, but how do these bubbles appear? What are the phenomena behind the famous sound of the “popping” of a bottle of champagne? Welcome to the magical and mysterious world of champagne.

When wine
becomes champagne

From grape juice to champagne, there is a whole process of incredibly precise chemical and physical transformation that takes place. At first, the grapes are pressed and then placed in a vat to undergo an initial fermentation, which is called alcoholic fermentation.

To this original juice a small quantity of “liqueur de tirage” is added composed of wine, sugar and yeast. This liqueur causes a second fermentation forming carbon dioxide. This “prise de mousse” [foam creation] represents the ultimate moment when the wine known as “still” becomes effervescent by giving birth to bubbles of carbon dioxide. Its alcohol content also increases to 12.5°.

How long does this “prise de mousse" last?

In 6 to 8 weeks, the yeasts will feed on all the sugar and produce alcohol and carbon dioxide. This gas gradually dissolves in the wine and the pressure slowly rises to 6 bars at the end of fermentation.

If it is handled several times, notably with the riddling stage which consists in stirring the bottle to make the sediment (yeast and riddling additives) go down into the neck of the bottle, then the disgorging stage which allows to eliminate this deposit, the wine continues its work of effervescence and will only let out the gas so sought after at the moment of the final opening of the bottle, this famous sparkling and joyful explosion which makes champagne unique and full of festive spirit.

The weather
as an ally

This transformation is not at all anecdotal because this fizz will have the effect of improving the aromatic qualities of the champagne wine by developing secondary aromas.

Placed in a horizontal position, the bottles will rely on time to develop beautiful, fine and harmonious bubbles. To do this, they need a low and constant temperature environment such as that found in champagne cellars. When the bottle is opened, the pressure created by the carbon dioxide escapes and makes the cork pop with that characteristic sound, the result of a long maturation.

But is this phenomenon the only one causing the effervescence?

The glass,
creator of bubbles

In addition to this alcoholic fermentation, another external element will cause the appearance of small bubbles. For a long time, it was believed that the irregularities of the glass champagne bottle were the cause of the appearance of bubbles. In fact, it is rather at the moment of serving the champagne that these bubbles come to life.

The small impurities or roughness inside the glasses allow the carbon dioxide to escape. Amazing, isn’t it?  Because even if it looks perfectly clean, a flute always contains irregularities. It is amusing to observe these small bubbles escaping in a column, starting from a fixed point in the glass and rising to the surface.

And how do you preserve these bubbles
when the bottle of champagne is opened?

Let’s put an end to a persistent legend, no the small spoon placed in the opened bottle of champagne will not retain the bubbles. To keep an opened bottle, it is better to use an airtight cap, which will be much more effective.

These technical explanations will never replace the elegance that emanates from a champagne bubble, that cheeky good-humoured “pop” when opening a bottle of champagne wine, but it is always exciting to lift a veil of mystery over this exceptional wine.