Particle size distribution of polysaccharides in beer before the filtration process

Abstract

Conventional beer filtration with diatomaceous earth as a filter aid causes a remarkable flow reduction due to the presence of yeast and colloidal particles formed principally by polysaccharides. The main polysaccharides of beer are dextrins, arabinoxylans (AX) and β-glucans (BG). Dextrins affect beer viscosity but not filterability, therefore the aim of this study was to quantify and characterize the two most influential polysaccharides in flow filtration: AX and BG. Scanning electron microscopy (SEM) and particle size distribution for each of the polysaccharides involved was performed. It was determined through SEM images a more compact and bigger formation of AX colloidal aggregates, even though both polysaccharides have the same diffusion limited method of aggregation. The greater size of AX compared to BG, might indicate that the concentration and the average size of AX could have a greater influence on filtration, resulting in a further reduction in the filtration flow