Carbonation refers to dissolved carbon dioxide (CO2) in beer, wine or soda. The container holding the liquid is held under pressure like in a keg or bottle. When the pressure is reduced, the carbon dioxide is released from the beverage as small bubbles.
So I was making kvass, and have decided to make it a little more alcoholic. I made it using the following recipe:
Slightly burn 3 pieces of toast, add to boiled water, and 1.5 handfulls of raisins.