Champagne Extra Brut is the AOC title for the very driest form of the world's most famous sparkling wine. It is sometimes informally expressed as 'Brut Nature' – a reference to the fact that the base wine is left 'au naturel', without any addition of sugar.
With only the very mildest dosage, the wine is fermented to within a few degrees of zero residual sugar. This is almost as dry as the yeasts can physically manage before they die off. According to EU law, Extra Brut wines must have no more than 6g/L residual sugar.
The result of this is that the production of Champagne Extra Brut is more susceptible to the effects of cool vintages, when sugar levels are at their lowest in the harvested grapes. With less natural sugar to digest (and thus convert to alcohol), and very little sugar being artificially introduced, the yeasts are unable to produce alcohol. This results in 'Extra Brut' cuvées being very low in sugar, high in acidity and slightly lighter in alcohol than their sweeter counterparts; these are not champagnes for the faint-hearted.
The official sweetness levels of champagne are:
- Doux (50+ g/L)
- Demi-sec (33–50 g/L)
- Sec (17–35 g/L)
- Extra-Sec (12–20 g/L)
- Brut (0–15 g/L)
- Extra Brut (0–6 g/L)
- Brut Nature/Zero (0–3 g/L).