In a previous post, I’d mentioned that sparkling wines are made in two basic ways. I’m going to go into a little more detail here about the more traditional methods now because I think they’re pretty interesting (the quickie, contemporary method is to just inject CO2 into the wine. Done.)
The older method, formerly widely referred to as Méthode Champenoise, is now pretty commonly just referred to as the “Traditional Method.” This is because the French are pretty dang picky about anything not made in Champagne bearing the champenoise label. The basic gist of how wines are made sparkling under this method is that they are fermented normally, but then undergo a secondary fermentation in some sort of enclosure (bottle or tank) and the bubbles come as a byproduct of that fermentation. The grapes are usually picked earlier, so that the starting wine has a higher acidity and lower sugar. Then, a sugary wine mixture and yeast are added, and the wine is bottled and tightly sealed (no sulphur dioxide is added here- in order to not kill the yeast.) Thus the carbon dioxide released by the yeast in this secondary fermentation is trapped in the bottle. The wine is then aged on this yeasty sediment (even though they’ve died) for varying times. The French have all sorts of laws relating to how long the wine must sit on the yeast, ranging from about 1-8 years. At this point, the winemaker is faced with getting the dead yeast cells and sediment out of the wine, without losing all of the precious carbonation. What to do?
Well, it’s actually pretty smart! The bottles undergo a process called riddling. They’re put into a rack that tips them upside down at an angle. Every day, they’re gently shaken and rotated till all of the sediment falls down into the neck of the bottle. Traditionally this was done by hand. Yes, a person would go in every day and shake and turn the bottles! Today, it’s usually done by machine. Even in Champagne. Then, the very top of the neck (or bottom, as they’re upside-down) is frozen. When the cap of the bottle is taken off, the ice plug shoots out, the bottle is topped up with a wine that is pH and sugar balanced, then it is corked, caged, and ready for labeling and sale! Voila! It’s neat that in this method, the wine undergoes the secondary fermentation in the same bottle it is sold in.
A twist on this Traditional Method is the Transfer Method. It seems a little silly to me in that the bottles undergo the secondary fermentation, but then are dumped into a tank, the wine is balanced for pH and sugar, and then is filtered and re-bottled. I think the reason they do this is to avoid the riddling process and speed things up a little. And even though it is done under pressurized conditions to avoid losing carbonation, I’d think it’d be not as fizzy, would risk oxygenation or microbial contamination, etc.
Another way of carbonating the wine is the Tank Method. Here, the secondary fermentation takes place in a large tank (pressurized to keep the carbonation in) and is then bottled from there. It is not as well-regarded a method because it doesn’t allow for the extended contact with the dead yeast cells that the other methods do. It is also sometimes referred to as the "Charmat Method."
To sum up (that was a lot of info, I know,) many modern wines are made by injecting CO2 into the wine like soda. Traditionally produced wines undergo secondary fermentation in the bottle, are aged on the dead yeast and stuff (lees) which is then removed and they’re bottled! The Transfer Method does the secondary fermentation in the bottle and aging on the lees, but then dumps the wine out of the bottles in order to remove the sediment. It’s then rebottled. And the Tank Method does the secondary fermentation in a large tank, but is not aged as long on the lees.
That’s it! That’s generally how sparkling wines are made!
Did you know?
Wine lees consist of dead yeasty sediment (actually a combo of live and dead yeast cells along with teeny tiny particles of grape left in the wine.) There is a French phrase called “sur lie” which means “on the lees.” Many sparkling wines are aged “sur lie,” as described above, but many other wines (usually whites) may also undergo extended contact with the lees. This imparts a sort of toast flavor to the wine and can be used to take a hard bite off of acidic whites.
Really extended contact time with the lees (months and months and months and months) in barrel or tank is referred to as bâtonnage, but as these cells start to decompose, the wine has to be stirred around frequently to keep a rotten egg smell from taking over. Ick.