Polysaccharides viscosity methods

The alternative large scale recovery method to precipitation is ultrafiltration. For concentration of viscous exopolysaccharides, ultrafiltration is only effective for pseudoplastic polymers (shearing reduces effective viscosity see section 7.7). Thus, pseudoplastic xanthan gum can be concentrated to a viscosity of around 30,000 centipoise by ultrafiltration, whereas other polysaccharides which are less pseudoplastic, are concentrated only to a fraction of this viscosity and have proportionally lower flux rates. Xanthan gum is routinely concentrated 5 to 10-fold by ultrafiltration. 

Sam- ple Nr Method for obtaining Polysaccharide yield g/L culture medium, g Polyuronides DE, PUAC, % % Molecular mass Intrinsic viscosity dlxg" Huggins constant Kh... 

The radii of gyration of amylose and cellulose are calculated by a method of Lifson for different glucose conformations. It is found that the radii of gyration differ widely and it can be determinated clearly by means of viscosity and light-scattering measurements which kind of glucose conformation is present in the polysaccharides. The effects of twisting upon the linear molecule is discussed. 

By methylation end-group assay. 1 Number-average degree of polymerization of methylated polysaccharide by id (isothermal distillation) or op (osmotic pressure) methods. c Viscosity-average degree of polymerization. 

T 0 is the solvent viscosity, II is the electrophoretic mobility, small for macroions relative to microions, and (j is the applied electromotive force across x. Neutral polysaccharides do not migrate in an electrical field, except as a moiety of an ionic complex or when they adsorb ions. Electrophoresis is a useful method for studying heterogeneity (Aspinall and Cottrell, 1970). 

Enhancement of transmembrane flux has been shown in OMD of grape juice pretreated by UF [131]. The increase in flux has been attributed to a reduction in the viscosity of the concentrated juice-membrane boundary layer as the result of removal of high-molecular weight biopolymers present in juice. UF is a powerful method for removing natural polymers (polysaccharides, proteins) from fruit and vegetable juices. Lukanin et al. [12] have improved the concept of (UF + OMD), by enzymatic pretreatment of the apple juice prior to the UF step. Introduction of an additional enzymatic deproteinization step with the pectinase/amylase treatment of apple juice followed by UF has yielded minimal biopolymer content. Such a treatment is found to enhance transmembrane flux during concentration of clarified juice by MD. As in the case of grape juice this has been... 

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