Determination of the molecular weight of barley β-glucan using intrinsic viscosity measurements

Molecular weight (MW) of polysaccharides determines their solution properties such as intrinsic viscosity [eta], flow and aggregation behavior. Determination of polysaccharide MW usually involves specialized equipment, extensive sample preparation and equipment calibration. Barley beta-glucan gum (BBG) was extracted at laboratory (LAB) and pilot plant (PP) scale. Its MW and critical concentration (c*) were determined using [eta] at infinite dilution. Solutions of beta-glucan standards (32-443 K), PP and LAB gums were prepared at different concentrations (0.025-0.20% w/w) and viscosity was measured at 25.8 s(-1). Intrinsic viscosity was calculated from linear and exponential extrapolation of reduced viscosity. PP and LAB gums had MW of 198 and 598 K, respectively. Mark-Houwink relationship between MW and [eta] was found to be different from previously reported findings. Calculation of c* was not applicable to low-viscosity BBG gums. Determination of MW through [eta] measurements is a simple method for characterization of P-glucan, which is a soluble fiber component receiving increased attention due to its health benefits. (C) 2003 Elsevier Ltd. All rights reserved.