Formation of Thermally Reversible Networks from Starch Polysaccharides
The main components of homopolymer mixtures in starches are different in chemical structures. The capacity to aggregate is determined by distribution of molecular weight of amylose andamylopectin and certainly by the length of exterior chains of the branched amylopectin molecules. Methods applied for measurement of the physical properties are time dependence of the dynamic viscosity, shear modulus and relaxation. The thermal behaviour has been investigated by the method of Ferry and Eldridge. In the presence of amylopectin the aggregation process of amylose is prevented and thermally reversible networks are formed. Small amounts of added soluble amylose increase the intensity of polymer interaction. Amylose molecules with a degree of polymerization < 500 are favourable for a high aggregation velocity. Amylopectin contributes to the rigidity as well as to the viscoelastic properties of the gel, largely depending on its molecular magnitude. The results lead us to assume that cooperative interactions between amylose and amylopectin diminish the extent of junction zones in comparison to amylose aggregates.
KeywordsShear Modulus Potato Starch Melting Enthalpy Elsevier Apply Science Publisher Shear Modulus Relaxation
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