Exopolysaccharides (EPS) produced by microorganisms are of great relevance due to their ability to modify viscosity, texture, and water-binding capacity in aqueous solutions. Their functionality can be estimated using intrinsic viscosity , a key parameter that is independent of concentration. Determining for isolated microbial EPS, however, is challenging due to polysaccharide characteristics (e.g., chemical structure, sample purity, dissolution behavior, and limited sample quantity). In addition to structural differences, the viscosity measurement system and calculation method can influence the resulting . In this study, various uncharged (exo-)polysaccharides were used to systematically compare measurement systems (rolling ball viscometry, rotational viscometry, and size exclusion chromatography with refractive index- and viscosity detectors (SEC-RI/VISC)) and calculation methods (linear, non-linear and single-point determination) for determination. For commercial dextran ( Leuconostoc spp., Leuconostoc mesenteroides ) and commercial levan (timothy grass), the applied measurement systems yielded comparable . Rotational viscometry showed higher data scatter than rolling ball viscometry. For isolated microbial EPS ( Gluconobacter albidus , Weissella confusa , and Streptococcus thermophilus ), sample impurities can affect determination with SEC-RI/VISC resulting in differences between measurement systems. The non-linear equation yielded higher than the linear equations, indicating that lesser weighting of the concentration can improve the fit quality. Single-point determinations yielded comparable to linear or non-linear regressions when the Huggins coefficient was in the expected range for good solvent conditions. • Intrinsic viscosity was independent of calculations for good solvent conditions. • Intrinsic viscosity was dependent of measurement system for high molecular masses. • Non-linear Wolf equation yielded high . • Higher data scatter in rotational viscometry than in rolling ball viscometry.
Panetta et al. (Wed,) studied this question.