Chemical Composition
While the actual foam activity of beer depends on the presence of carbon dioxide, it is the surface-active materials like amphipathic polypeptides from malt that determine size, shape and length of the foam.
Beer foam consists of polypeptides of five different classifications, divided by their relative hydrophobicity. As the hydrophobicity of the polypeptide groups increases, so does the stability of the foam.
Carbonation occurs when carbon dioxide is dissolved in water or an aqueous solution. This process is generally represented by the following reaction, where water and gaseous carbon dioxide react to form a dilute solution of carbonic acid.
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