Carbonation
From Wikipedia, the free encyclopedia
Carbonation occurs when carbon dioxide is dissolved in water or an aqueous solution. This process yields the "fizz" to carbonated water and sparkling mineral water, the head to beer, and the cork pop and bubbles to champagne and sparkling wine.
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[edit] Effervescence
Effervescence is the escape of gas from an aqueous solution. The term is usually used to describe the foaming or fizzing that results from gas. In the lab a common example of effervescence is the addition of hydrochloric acid to a block of limestone. If a few pieces of marble or an antacid tablet are put in hydrochloric acid in a test tube fitted with a cork, effervescence of carbon dioxide can be witnessed.
This process is generally represented by the following reaction, where a pressurised dilute solution of carbonic acid in water releases gaseous carbon dioxide at decompression.
- <math> \mbox{H}_2\mbox{CO}_3 \longrightarrow \mbox{H}_2\mbox{O} + \mbox{CO}_2</math>
Effervescence is the cause of bubbles in fizzy drinks (carbon dioxide escaping water), beers and sparkling wines.
In simple terms, it is the result of a chemical reaction occurring in a liquid which produces a gaseous product.
[edit] Fizz
"Fizz" is a word that is used to describe the action or sound of gas bubbles moving through and escaping from a liquid, or the formation of an emulsion of this gas and liquid at the top of the liquid's container. The word itself is an example of onomatopoeia, derived from the sound the multiple bubbles make together as they "pop" when they escape. A carbonated beverage, such as cola or beer, will form bubbles when the dissolved carbon dioxide is depressurized to form emulsions at the top, and it will make "fizzing" sounds when it is opened or poured into a container.
Fizz can also result from a chemical reaction, such as a solid dissolving in a liquid to produce gas. For example, Alka-Seltzer brand tablets, used to treat stomach indigestion, form an effervescent solution that fizzes when dropped into water.
[edit] Natural and artificial carbonation
Carbonation can occur as a result of natural processes: when yeast ferments dissolved sugars sealed in a pressure-tolerant bottle or keg; when underground volcanic carbon dioxide carbonates well water; or when rainwater passes through limestone into a cave and forms a stalactite. Or it can be done artificially by dissolving carbon dioxide under pressure into the liquid. Sometimes natural carbonation is called conditioning while the term carbonation is reserved for the artificial process.
[edit] Uses
In many consumer beverages such as soft drinks (well known examples include Coca-Cola, 7 Up and Pepsi), carbonation is used to give "bite". Contrary to popular belief, the fizzy taste is caused by the dilute carbonic acid inducing a slight burning sensation, and is not caused by the presence of bubbles. This can be shown by drinking a fizzy drink in a hyperbaric chamber at the same pressure as the beverage. This gives much the same taste, but the bubbles are completely absent.
Carbonation is sometimes used for reasons other than consumption, to lower the pH (raise the hydrogen ion concentration) of a water solution, for example.
[edit] Brewing
In homebrewing overcarbonation can be dangerous: it can result in bottles gushing or even exploding. Adding priming sugar or malt extract at bottling time to beer that has had its fermentable sugar content totally consumed is the safest approach to carbonation. Exceeding recommended levels of priming sugar for a given recipe is dangerous, as is using inappropriate bottles or improper capping methods. Beer may also be force-carbonated using a keg and special bottling equipment, where the carbonation level can be carefully controlled.
[edit] Carbonated beverages
Carbonated beverages are beverages which contain dissolved carbon dioxide. The process of dissolving carbon dioxide in water is called carbonation. Carbon dioxide may be naturally occurring in the beverage from fermentation or a mineral source or be artificially added.
[edit] Testing carbonation
In breweries and soda bottling plants, carbonation is measured using one of three methods. Infrared carbonation sensors measure the vibrational frequency of dissolved CO2 and give a specific concentration not affected by other dissolved gases. The scientific principle is defined by Beer Lamberts Law. Another method uses Henry's Law. By measuring the pressure and temperature of a fluid in a sealed container, the concentration of all dissolved gases in water can be calculated. This is the most commonly used technique. The disadvantage of this technique is that the measurement is affected by other dissolved gasses, specific gravity and solubility coefficients. Another method is dissolved gas by weight. This is done by weighing the fluid in a sealed container and then driving off all the gases by heating the fluid. This method does not specifically measure CO2 but all dissolved gases. It has the added disadvantage that heat drives off fluid as well as gas.
[edit] References
- Robert O'Leary VitalSensors Technologies LLC. Attenuated Total Reflection Spectroscopy Method for Measuring Dissolved CO2 Concentration in Beer.— O'Leary describes the theory and practice of measuring carbonation in beer.
- Laboratory Methods for Craft Brewers, Edited by Rena M. Crumplen
- In-Line Determination of Carbon Dioxide in Beer by Infrared Analysis, Paul A. Wilks, MBAA Technical Quarterly, Vol. 25, No. 4 pp. 113-116
[edit] Further reading
- Richard J. Kinch. Carbonating at Home with Improvised Equipment and Soda Fountains. — Kinch describes in detail the theory and practice of constructing one's own home carbonation system.
[edit] See also
- Beer
- Carbonated water
- Champagne
- Charmat process
- Cola
- Méthode champenoise
- Sparkling wine
- Soft drink
- Tonic water
- Mentos eruption, uses carbonated liquid
