ON HEAD RETENTION

The Σ-test for foam stability may give misleading results, and it is inadmissible to determine this value after dilution; moreover, the foam residue towards the end of degradation has enhanced stability. In a described method for determining “foam time,” beer is foamed under standard conditions and the time is found for 95% of the beer to return from the foam. This measurement, however, does not sufficiently characterize the foam properties of a beer, and it is proposed also to measure “foam adhesion,” obtained from the position of the highest persistent foam ring on the wall of the experimental cylinder. Foam time depends on high-molecular protein degradation products and on the hop rate, whilst foam adhesion depends almost entirely on the hop rate and, more specifically, on humulone transformation products, roaming properties are not significantly affected by esters, higher alcohols or barley fat, in the quantities likely to occur in beer.