What Is Carbonation?
Carbonation is the process of dissolving carbon dioxide gas in a liquid. In order to keep the carbon dioxide gas within the liquid, pressure is required. In the case of beer, this pressure is created by a sealed bottle cap or tab. When the pressure is released, the carbon dioxide rises to the surface in the form of bubbles or carbonation.
All beer is carbonated before it leaves the brewery. There are two methods used to achieve this—natural carbonation and forced carbonation. In both cases, the beer and carbon dioxide are sealed in a container under pressure. The beer absorbs the carbon dioxide, resulting in the fizziness of the beer.
What Is Natural Carbonation?
Natural carbonation occurs during the fermentation process. As yeast digests the sugar in the wort, it produces alcohol and carbon dioxide. Although most of the carbon dioxide escapes during fermentation, the brewer seals the beer in a container when it is almost finished. This technique is used to carbonate beer in holding vessels at the brewery and in casks.
Another way to achieve natural carbonation is through bottle conditioning. In this method, the beer undergoes complete fermentation and is left unfiltered, which means active yeast is still present in the liquid. A small amount of sugar is added at bottling time. As the yeast acts on the sugar, it releases carbon dioxide, which is then absorbed by the beer.
What Is Forced Carbonation?
In forced carbonation, the beer completes fermentation and then carbon dioxide is pumped into a sealed container with the beer, where it is absorbed into the liquid. This method is commonly used for kegs. After refrigeration, carbon dioxide is pumped into the keg of beer. Over a few days, the carbon dioxide is absorbed, fully carbonating the beer.
Keeping Beer Carbonated
To maintain carbonation, beer must be tightly sealed with a bottle cap. This ensures that no carbon dioxide escapes until the beer is opened. Once a beer is opened, it should be consumed within a few hours. Leaving it for longer will result in loss of carbonation, causing the beer to go flat and lose its enjoyable qualities. Beers with a low alcohol by volume (ABV) percentage can be stored unopened for approximately 6 months, after which they may go flat. Beers with a higher ABV are often suitable for aging, and leaving them unopened for a few years can actually enhance their flavor. Examples of beers that can be aged include lambic and stouts.
Proper Beer Storage
Beer is sensitive to light, so it should be packaged in dark bottles and stored in a cool, dark place away from sunlight. If the beer is in a keg or can, these containers are both light-proof, ensuring the beer remains protected from bright light.