We recent asked Bele Casel’s to tell us a little bit about the tirage for the winery’s Colfòndo. Here’s what he had to say.
All sparkling wine is made by making a base wine, in other words, a first fermentation of grape must. Once the base wine has been fermented, it is the fermented a second time (second fermentation) by the addition of sugar and yeast. The second fermentation is carried out in a sealed environment. And as a result, the CO2, a natural by-product of fermentation, is captured in that environment, be it a bottle or a tank.
In the case of Prosecco Col Fondo (or Colfòndo, as Bele Casel likes to call it), the winemaker is not allowed to add cane sugar. And so the winery uses reserved grape must. The Prosecco DOCG does include a col fondo, i.e., re-fermented in bottle wine (in Italian it is called rifermentato in bottiglia). But it can only be made using reserved grape must or concentrated grape must.
What is grape must? It’s the juice and the solids that result from the pressing or crushing of the grapes. Essentially, it’s unfiltered grape juice.
In the case of Bele Casel’s col fondo, they reserve some of the must at harvest and they keep it stable in a pressurized and temperature-controlled tank that keeps the must from fermenting spontaneously. The key is the cool temperature and the lack of oxygen.
When it comes time to re-ferment the base wine, the winemaker uses the reserved grape must for what is called the tirage, a French term used to denote the provocation of the second fermentation by adding sugar (in this case, sugar from the grape must) and yeast. Luca noted that the tirage is in many ways one of the most difficult elements in making these wines. They have to put just the right amount of sugar in so that it’s all consumed by the yeast. Otherwise, the wine could have residual sugar and be too sweet.