Wine glossary

carbon dioxide / CO2
Definition:

The common term for carbonic acid (carbon dioxide), which is formed during the alcoholic fermentation and the malolactic fermentation. Due to the fact that fermenting gases are heavier than air, it can be a potential health hazardous in the cellar during fermentation. CO2 is a colourless gas often added to white wines during bottling to enhance freshness. In the production of sparkling wine, carbon dioxide is produced during the second fermentation and is responsible for its characteristic mousseux.