Carbon dioxide - Beer, Wine, Mead, & Cider Brewing Discussion Community.

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Carbon dioxide is a colorless, odorless gas that is created as a byproduct by most strains of yeast.

When fermentation takes place in an enclosed space, as with bottle conditioned or cask conditioned beer, the increased gas pressure forces the carbon dioxide into solution, thereby carbonating the liquid. Pressure can also be applied using a canister of high-pressure carbon dioxide to carbonate the beverage; this is known as force carbonation.