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Beer Carbonation
Methods of Carbonation
Secondary Fermentation
The traditional method involves carbonating the beer during secondary fermentation at low temperatures and under counterpressure. The beer transferred to the conditioning tank should have at least 0.5 to 1.0ºP of fermentable extract and be placed under pressure from 12 to 15 psi in conditioning tanks (15). Munroe reports that if the pressure is too high during secondary fermentation, yeast growth may be affected and change the flavor characteristics of the beer (19). While in the tank, the remaining extract ferments and creates sufficient carbon dioxide to saturate the beer to equilibrium.
Mechanical
Mechanical carbonation is accomplished either by in-line or in-tank techniques. Carbon dioxide may be purchased from suppliers of industrial gases. Alternatively, carbon dioxide may be recovered from fermentation vessels and then purified, liquefied, and stored until needed for carbonation. However, this collection system can be too expensive for most craft brewers. In general, the viability of collecting carbon dioxide depends on an alternative cost of purchased carbon dioxide, its availability, and the quantity used in the brewery. Some brewers report that use of mechanical carbonation actually has a greater influence on reducing acetaldehyde levels than does kraeusening the beer.
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