90. The forcing test to estimate beer stability—Influencing parameters and optimization potential

Roland Pahl (1); (1) VLB Berlin, Berlin, Germany


The forcing test (e.g., according to MEBAK represents a well-established method to estimate the haze stability of beer. Forcing tests are often implemented in quality control measures of breweries, as well as in external product quality tests. Parameters that possibly influence the results of forcing tests were tested and evaluated in a research project at the VLB Berlin e.V. The kinetics of temperature transfer represent one of the crucial factors for inducing turbidity in beer. The kinetics are influenced by the heating, as well as the cooling, device. In model solutions different parameters, e.g., volume, time, heating medium, were tested. Furthermore, the temperature at the moment of turbidity measurement is an important parameter. To illustrate the influence, beer samples were measured at different temperatures during long-term forcing tests. In a comparison study four different beers were aged according to the forcing test method described in MEBAK The turbidity was measured with five different turbidity meters, and the results were compared. The results revealed minor deviations depending on the measurement device used. In conclusion it was shown that the forcing test (MEBAK is able to show differences in the product stability for beer. To improve the consistency and liability of the results certain influencing parameters should be controlled. Potential for improvement is discussed for total analysis time and interpretation of results (stabilization efficiency).

Roland Pahl heads the Research Institute for Beer and Beverage Production within VLB Berlin. Roland started his brewing career with an apprenticeship at Berlin Schultheiss Brewery. After working as a brewer he started his studies in brewing technology at the University of Technology of Berlin. Starting to work for VLB Berlin in 2002, he became head of VLB’s Institute for Engineering and Packaging in 2007. In 2011 he obtained his Ph.D. degree in brewing technology and has been in his current position since 2014.