Effects of Molecular Weight and Concentration of Arabinoxylans on the Membrane Plugging

In this paper, arabinoxylans from wheat were isolated, purified, and degraded into four fractions with different molecular weight. The distribution of particle size was employed to evaluate the membrane plugging by beer. These arabinoxylans fractions were added into arabinoxylan-free beer to investigate the effects of molecular weight and concentration on the distribution of particle size in beer. Results showed that the fraction of arabinoxylans retained by a 0.22-μm pore size membrane was more easily affected by shearing and arabinoxylan concentration than the fraction of arabinoxylans retained by a 0.45-μm membrane. The effects of shearing, pH, and ethanol concentration of beer on the particle size distribution of the highest molecular weight arabinoxylan fraction in beer were also examined. General linear models (GLM) equations indicated that there was a positive correlation between the particle size distributions of arabinoxylans and shearing and ethanol content, while high molecular weight arabinoxylans particle size retained by the 0.45-μm membrane was not significantly (p > 0.05) influenced by pH value. Scanning electron microscope (SEM) photos showed that membrane plugging was significantly affected by the molecular weight of the arabinoxylans. Keywords: Arabinoxylans; beer; membrane plugging; shear