Liqueur de Tirage [pronunciation: li-kyoor de ti-rahj ]
The solution added to the base wine at initial bottling to induce the second fermentation, composed of wine, yeast and sugar. The added yeast consumes the sugar, producing carbon dioxide, which is trapped in the sealed bottle, resulting in the formation of bubbles or effervescence. This is a key step in Méthode Traditionnelle.
As a general rule, four grams of sugar per liter of wine will produce one atmosphere of pressure. The standard measurement in Champagne is 24 grams of sugar, which produces roughly six atmospheres (88 psi), although a little may be lost at disgorgement. That’s just a little less than the pressure in a city bus tire!