Part IV · How wine is made · 2 min
Bubbles, fortified and sweet
Sparkling, fortified and sweet: three ways of interrupting a fermentation.
Making bubbles
Every sparkling wine is a wine that fermented twice, with the second fermentation’s carbon dioxide trapped instead of released. Where you trap it decides everything.
| Method | Second ferment in | Gives | Examples |
|---|---|---|---|
| Traditional (méthode traditionnelle) | The bottle sold to you | Fine persistent bead, brioche, autolytic depth | Champagne, Cava, English sparkling, New Zealand |
| Tank (Charmat) | A pressurised tank | Larger bubbles, fresh primary fruit, lower cost | Prosecco, Lambrusco |
| Ancestral | The bottle, one unfinished ferment | Cloudy, unpredictable, low pressure | Pétillant naturel, or pét-nat: "naturally sparkling" |
| Carbonation | Nowhere - gas injected | Coarse, short lived bubble | Cheap fizz |
The traditional method is expensive because of time rather than ingredients. The bready complexity comes from years resting on dead yeast cells, and those are years the producer has paid for the stock and can’t sell it.
Fortification
Add neutral grape spirit and the alcohol jumps to 15-22%, past what yeast can survive. When you add it is the whole difference between the styles.
- Mid-fermentation - yeast dies while sugar remains, leaving a sweet, strong wine. This is Port, and the reason it’s both sweet and 20%.
- After fermentation - the wine is already dry and simply becomes stronger. This is Sherry.
Sherry then divides again by whether it ages under flor, a living film of yeast that grows across the surface of the wine and keeps oxygen off it. Under flor you get Fino and Manzanilla: pale, bone dry, saline, tasting of almonds and sea air. Without it the oxygen gets in and you get Oloroso: dark, nutty, still dry. Pedro Ximénez, from sun dried grapes, is the sweet one, and is almost black.
Sweetness without fortification
To leave sugar in an unfortified wine you must concentrate it in the fruit until the yeast gives up. Three routes, all of them expensive.
- Noble rot - Botrytis cinerea punctures the skins and dehydrates the grape, concentrating sugar, acid and glycerol while adding a marmalade and saffron note. Sauternes, Tokaji, German Beerenauslese.
- Freezing - grapes are left until frozen solid and pressed while frozen, so the water stays behind as ice. Eiswein. Requires a hard frost after ripening, which doesn’t arrive every year.
- Drying - grapes are laid on mats or hung to raisin. Vin Santo, Recioto della Valpolicella, Commandaria.