Rheological Studies on Biopolymers

Abstract

Rheological and related physicochemical Studies on biopolymers are reviewed. Methods of determining viscoelastic constants of cylindrical gels were proposed and applied to various polymer gels. This was convenient to study the rheological changes induced by diffusion of ions into gels, and those induced by retrogradation of starch gels. A reel-chain model was proposed to understand the temperature dependence of elastic modulus of thermoreversible gels Such as agarose, gelatin, poly(vinyl alcohol), gellan etc. This model was extended recently to understand the large deformation and yield behaviour of physical gets. Gelation process of various food biopolymers, soybean protein, casein, konjac glucomannan, gellan as well as the interaction between different biopolymers have been studied by dynamic viscoelastic measurement in combination with other physicochemical methods. Rheological behaviors of hyaluronan, a major component of synovial fluid, and of schizophyllan, anti-tumor active and very rigid rod polysaccharide, were studied. Viscoelastic properties of films of polysaccharides, amylose, pullulan, cellulose derivatives, konjac glucomannan were studied as a function of temperature and were analysed from the view point of molecular motion with NMR and dielectric studies as a basis of molecular understanding of biodegradability.