Sparkling wine is a specific type of wine that is additionally enriched with carbon dioxide produced in the secondary fermentation process. According to European law standards, sparkling wine should contain not less than 1.2% but not more than 15% of alcohol. Additionally, all alcohol contained in the wine must come from the fermentation process. Bubbles in sparkling wine are created as a by-product of fermentation. In the classic champagne method, secondary fermentation takes place in the bottle. In the Charmat method, secondary fermentation takes place in specialized pressure tanks. The resulting carbon dioxide causes the pressure in the tank to increase, up to 6-8 bar.