Protein separation by differential drainage from foam

Commercially available beer, which is a dilute solution containing components of yeast, malt, and hop used in the manufacture of the beer, was used as a model system to demonstrate the potential of foam fractionation beyond the primary foaming stage. Most of the components present in the beer concentrated in the initial foam, but they drained differentially in the subsequent collapsed foam collected over a period of 30 min. This resulted in further enrichment, in particular, of components which were present in low concentration in the original beer, Preferential drainage from foam, hence, might provide a novel way of fractionating further the proteins concentrated initially in the liquid films of foam. (c) 1994 John Wiley & Sons, Inc.