🍷 Charmat method

The Charmat method is a way of making sparkling wine in which the second fermentation takes place in a hermetically closed, pressure-resistant tank rather than in the bottle. The OIV International Code of Oenological Practices calls it bulk second fermentation in a closed tank and distinguishes two variants: discontinuous and continuous.

In the discontinuous variant the operations are: preparing the base wine or cuvée, preparing the tirage liqueur, inoculating with yeasts, adding clarifying agents, tirage in the closed tank, storage in the tank, clarification of the sparkling wine, cooling, addition of the dosage and isobaric bottling. According to the Code, only tirage, storage, cooling, bottling and dosage differ from the bottle method. During storage the tank is stirred several times, and its temperature must be low enough to give a good effervescence without stopping fermentation.

Clarification and bottling are carried out under isobaric conditions: the pressure is kept with an inert gas or compressed air, and the authorised inert gases are nitrogen, argon and the wine's own carbon dioxide. Before bottling the wine is cooled to lower the pressure.

In the continuous variant the base wine enters a system of several hermetically closed, connected tanks. Once started, the system runs without stopping for several years (3 to 5, depending on circumstances).

As for any sparkling wine, the excess pressure of carbon dioxide in the bottle must be at least 3.5 bar at 20 °C (3 bar for bottles under 0.25 l).