Thank you Rachael Liggett-Draper, Jeremy Eubanks, and Dustin Chabert for your responses last week on closure types!
This week: Disgorgement
What are various methods of disgorging sparkling wine and how does the disgorgement date impact the overall flavor?
For Traditional Method wines, disgorging is done by plunging the neck of the bottle into a solution that is very cold (-27C) to freeze the plug of yeast that has collected there through remuage. The bottle is then opened and the frozen plug is forced out by the pressure in the bottle. This process is mechanized, though the manual technique (à la volée) is still employed for large and small format bottles as well as for very old wines. The manual technique freezes the neck of the bottle and then the bottle is held inverted, opened, and quickly righted to minimize loss.
Ancestral Method is disgorged in the same manner as Traditional Method. There is no dosage.
Wines made in the Transfer Method can skip the freezing step as they are disgorged into pressurized tanks and then filtered prior to re-bottling for dosage and final packaging.
The Transversage Method differs from the Transfer Method in that the wines are disgorged as in the Traditional Method, then emptied into a pressurized tank where the dosage is added. No filtering is necessary.
Charmat (Tank) Method, and Continuous Method do not involve disgorging.
The date of disgorgement has a significant impact on flavor in two ways. First is the impact of the amount of time spent in tirage, and the second is the amount of time elapsed from disgorging to consumption. The time spent on the lees will contribute to the development of the bready, toasty, yeasty, leesy family of flavors and aromas. The longer on the lees, the greater the development of these flavors and aromas. The time on the lees not only creates the effervescence of the wine, but refines and integrates the bubbles as well. Wines consumed within the first three to six months after disgorgement are more likely to present sharp, sour flavors and have a clipped palate. Most wines need time in bottle to relax.
I'll add the Freezing neck method is called "a la glace."
The bottles have a small capsule inside to catch the plug of yeast called a bidule.
The bottles are usually sealed with a crown cap, but sometime have a cork.and staple (agrafe)
The jump in productivity from the methods by hand (a la volee -400 bottles/hr ; a la glace -800 bottles an hour) to mechanized (1500 bottles an hour) is significant, though some small producers insist on a path volee so they can smell every bottle of wine.