Gushing Laboratory Tests as Successful Methods for Obtaining New Cognitions on Gushing

This work investigated the gushing phenomenon in wort samples by applying commonly used gushing tests (Weihenstephaner and modified Carlsberg test) in order to identify conditions for the development of gushing. The mashing and boiling procedures were modified (Weihenstephaner test), and the amount of wort and time of shaking of the bottle were increased (modified Carlsberg test). For the experiments one malt sample was applied that was identified as gushing-positive (Weihenstephaner test). A changing pattern of the mashing process revealed that gushing was induced after heating up to 97 °C while no gushing was observed until 80 °C. Heating up the mash from 80 °C to 100 °C and boiling it for 5 min afterwards sufficed for gushing to be induced in the wort sample..

From the applied malt sample it was possible to produce not only a gushing-positive wort but also a gushing-negative one. By mixing these wort samples, gushing could be reduced, or even entirely suppressed, applying a volume of only 10 % v/v of the gushing-negative sample. The gushing-positive wort could only induce gushing in amounts of above a critical level. Gushing started to develop after a mild shaking for 10 h (modified Carlsberg test) and increased significantly after 20 h of shaking. The results demonstrated that the temperature of the mash is a decisive parameter for the development of gushing.

BrewingScience - Monatsschrift für Brauwissenschaft, 62 (May/June) 2009, pp. 83-89