Aspects of beer foam formation and head retention.

Heintz, O.E.

Abstract
The composition of beer foam and factors influencing its formation and stability are described. Foam quality is largely governed by the interaction of hydrophobic and hydrophilic substances. The most stable foams are formed by the synergism between hydrophobic materials, hop resinous substances and trace metals. The rate of head formation is dependent to an important degree on the carbonation level in beer and the rate of collapse on bubble size and uniformity. The best foams contain small tightly-knit bubbles. As proteinacous materials in the molecular weight range 5000 to 60000 are regarded as the principle building blocks of foam the degree of proteolytic activity taking place during malting and mashing is of major importance. Iso-alpha-acids are a significant part of good foam. Lipids are generally foam negative. Recommendations are made on measures to be taken during malting, mashing, lautering, wort boiling, hopping, fermentation, carbonation and handling if the quality of beer foam is to be optimized.
Keywords : adhesion beer cling foam head stability