Critical review of the methods of β-glucan analysis and its significance in the beer filtration process

β-Glucans are polymers containing β-glycosidic linkages that occur in beer as degradation products of yeast and cereal cell walls. These polysaccharides are known to have a technological influence on the filter performance time because of their functional properties as viscous, gel-forming hydrocolloids. Despite knowledge of the impact of β-glucans on filterability gained using model solutions, these results can only rarely be transferred to the brewing process. Because current quantification methods are based on various chemical and physical properties of these polymers, comparisons between methods are limited. Significant results concerning kieselguhr filtration, particularly the gel content, were assayed using fluorometric methods. Furthermore, viscosity measurements yielded a good correlation with kieselguhr filtration. Informative results for membrane filtration could be obtained using chromatographic separation of the sample and detection of high molecular weight fractions (>90 kDa) using enzymatic degradation. Although β-glucan molecules affect both kieselguhr and membrane filtration, the molecular fractions involved and their physical properties differ, as demonstrated using the measurement methods described.