Influence of the malting parameters on the haze formation of beer after filtration

Malting changes the chemical and enzymatical composition of barley. During malting, enzymes are synthesized, cell walls (pentosans, proteins, etc.) degraded and starch becomes available for enzymatic attack. The progress of germination defines the final beer quality and processability in several aspects: mouthfeel, foam and haze formation (different proteins), processability (viscosity caused by certain substances, like β-glucan), fermentation progress (FAN, sugar content), etc. The objective of this research was to study the influence of different modified malt on turbidity in beer after filtration. This was achieved by analyzing selected malts at different germination stages and afterward studying their influence on the final beer composition, focusing on protein content and composition. Protein fractions were analyzed using a Lab-on-a-Chip technique, which separates the proteins-based on their molecular weight-by capillary electrophoresis. This analysis was supported by the use of two-dimensional gel electrophoresis (2D-PAGE). Additionally, common malt and beer analyses and turbidity and filterability measurements were performed. The protein composition could be followed from malt to beer with both the Lab-on-a-Chip technique and 2D-PAGE. No differences in protein composition could be seen in the final protein composition of the beer. However, it could be observed, with Lab-on-a-Chip technique, that high amounts of a protein fraction with a size of 25-28 kDa caused increased turbidity in the beer.