VIEW ARTICLE    DOI: 10.1094/ASBCJ-49-0014

Foam Stability and Physicochemical Properties of Beer. Katsuaki Maeda, Shigehisa Yokoi, Kozo Kamada, and Minoru Kamimura, Brewing Research Laboratories, Sapporo Breweries Ltd., Yaizu, Shizuoka, Japan 425. J. Am. Soc. Brew. Chem. 49:0014, 1991.

The surface viscosity of beer was investigated using rotational surface viscometry to obtain information on its role as a factor in beer foam stability. Beer proteins were also studied in relation to surface viscosity, adsorption onto air bubbles, surface tension, and foamability in order to reveal the effects of the proteins on foam stability. The surface viscosity of beer increased with time, where the force-flow curves showed that the surface changed from Newtonian to non-Newtonian. A close correlation was recognized between the velocity of increase in apparent surface viscosity and the ? value. Among beer proteins, the 40-kilodalton protein possessed the highest surface viscometric activity, the highest adsorption affinity to air bubbles, the highest surface activity, and a rather high foamability. These results showed that the surface viscosity of beer correlated with the foam stability and that the 40-kilodalton protein had favorable properties-a strong tendency to gather and to remain on the surface of the liquid film of foam and then to stabilize the foam.

Keywords: Adsorption onto air bubbles, Beer proteins, Foamability, Foam stability, Surface tension, Surface viscosity