Determination of the foam stability
Beer and beer-based beverages
In determining the foam stability with the Steinfurth Foamtester SFT, the time required for the foam to collapse in a graduated cylinder is measured.
The pressurization is carried out in such a way that the container does not require degassing. The attempered beer is injected into the measuring cylinder through a nozzle, and in the process, foam is formed. The foam stability is determined by several optical sensors detecting the time necessary for the beer/foam interface to pass by them. The precise metering of a predetermined quantity of beer, the entire process of executing the analysis and displaying the results as well as cleaning and conditioning of the measurement cylinder are performed automatically.
Determination of the foam stability
Beer and beer-based beverages
In an Lg foam tester, the foam stability is determined by measuring the time it takes for the foam to collapse in a glass cylinder.
The foam is produced by pressing a constant beer volume through a nozzle (Ø 0.6 mm). The precise metering of a predetermined quantity of beer is achieved by time-controlled operation of the valve in conjunction with pressurizing the sample bottle to 2.5 bar (± 5 mbar). As the foam collapses, the height is measured optically in the glass cylinder [1].
beer, beer-based beverages, non-alcoholic beverages, mineral water
One of the basic prerequisites for properly conducting sensory analysis is selecting suitable candidates as members of the tasting panel.
This method describes the conditions under which sensory analysis is to be performed.
Beer, beer-based beverages, non-alcoholic beverages, mineral water
One of the fundamental prerequisites for a properly structured sensory evaluation of beverages is training members of the tasting panel.
This method describes the conditions under which sensory analysis should be carried out.
beer, beer-based beverages, non-alcoholic beverages, mineral water
One of the basic prerequisites for properly conducting sensory analysis is the availability of suitable persons to serve as members of a tasting panel.
Determination of foam stability
Beer and beer-based beverages
Determining foam stability using a NIBEM foam stability tester entails the time in which the surface of a head of foam collapses in a
standardized cylinder. Four separate phenomena cause foam to collapse:
| Coalescence: | the fusion of two bubbles |
|
Disproportionate pressure: |
diffusion between bubbles due to pressure differences in the bubbles |
|
Drainage: |
liquid exiting the foam |
| Diffusion of other gases: |
the creation of an equilibrium between the gas in the bubbles and the ambient air |
A movable system of electrodes tracks the surface of the foam (foam level) by means of electrical conductivity. One long needle is immersed in the center of the foam. The electrodes descend until one of the four outer needles touches the surface of the foam, at which point the electrodes stop their downward motion. The electrodes are motionless until contact to the outer needles is broken as the foam collapses, whereupon the electrodes begin their downward motion once more until they again come into contact with the foam. A timer built into the device measures the time for the foam to collapse (10/20/30 mm). After the measurement is completed, the electrode system returns to its initial position and the measured value is displayed in seconds.
NIBEM: Nederlands Instituut Brouwgerst, Mout en Bier, Dagelijkse Groenmark 3-5; 2513 AL Den Haag; Postbus 179; The Netherlands