Palate-Fulness and Foam-Stability of Beer

The American Brewers’ Review  –  1905

Meeting of the Munich Station

The twenty-eighth regular meeting of the members of the scientific station for brewing of Munich was held October 21, 1904. This was among the addresses given.

Palate-Fulness and Foam-Stability of Beer. — By Prof. Dr. LINTNER

Palate-fulness and foam-stability are highly prized properties in beer. Palate fulness was connected with the amount of viscous matter and identified with viscosity. For the purpose of estimating it, REISCHAUER constructed a viscosimeter, by which the velocity of flow of a certain quantity of beer of constant temperature is measured. He took that of the beer from the Hofbrauhaus at 100. Dextrins, and more particularly the higher ones, and albuminoids, exert very great influence on palate-fulness. This is less the case with maltose and glycerin, and still less with the mineral substances. On the other hand, much importance attaches to the hop resins and gummy substances.

The production and stability of foam is governed, aside from carbonic acid, by colloidal substances, as proteids, gummy bodies and hop resin. In contradistinction from the crystalloids, with which lower dextrins form a connection, they are generally only strongly swelled in water. The most important colloidal matters, both in quality and quantity, are the proteids.

Foam is formed by the bubbles of carbonic acid at the surface taking on a delicate film of the colloidal solution. The greater the viscosity of this solution, the greater the consistency of the foam. As distinguished from dextrin and sugar, caramel is a good foam producer. The best are the albumins which, however, are eliminated by boiling the wort. A substitute is supplied by the hop resin, including the gamma-resin. During fermentation and storage more foam producers are eliminated. The addition of water, according to EMSLANDER, has a favorable influence upon foam production. Yeast may also have a favorable influence upon foam-stability.

The foam producers can be precipitated by shaking the ether or by electrolysis. In that manner positive colloids are obtained which have the property of absorbing acids, including carbonic acid, according to the laws of surface tension. This surface action is diminished by bodies soluble in ether, as fat and ethereal hop oil, which is the reason why these bodies diminish the foam-stability. While we are fairly well informed concerning the producers of palete-fulness, and foam-stability, reliable data are lacking for the optimum of their action since the raw material and the preparation of the malt are quite as influential as the boiling process and cellar treatment.