Particularities in the structure of amylopectin, amylose and some of their derivatives in solution

Abstract

Because of a well defined supramolecular architecture of the native starch granules the preparation of molecularly dispersed starch solutions is achieved only after autoclaving at temperatures of 135 to 160 C. A detailed analysis of static light scattering data allowed the determination of the molecular parameters of both the amylopectin and amylose. The results were confirmed by (1) measurements in the iron sodium tartrate complex FeTNa, (2) by extrapolation of the data obtained with degraded starches to no degradation and (3) by sedimentation field‐flow‐fractionation sFFF. Above the overlap concentration strong aggregation due to H‐bonding commenced and eventually led to gelation. The process is promoted by the amylose content and could be followed by static and dynamic light scattering. Cationic starches and cationic amyloses display remarkably different behavior. The branched amylopectin expanded uniformly when the ionic strength was lowered but the corresponding amylose exhibited an unusual helix‐disorder transition.

Solvent composition and rheology of starch–DMSO–water solutions

“…In the case of starch, helix–coil transition in amylose is highly involved in the process of gelation,11 the mathematical description of which is quite complex, even if one works with the simulation of these macromolecules in vacuum 12. When in solution, new variables are added to the problem: the competition between polymer–polymer and polymer–solvent interactions becomes increasingly important.…”

Friction properties of chemically modified starch

“…The molecular weight of a starch biopolymer is dependent on its structure. The estimated molecular weight of a linear starch biopolymer amylose is in the range of 0.5-2.0 × 10 6 [7]. The molecular weight of amylopectin is several orders of magnitude higher than that of amylose starch [1,8].…”

Sustained release properties of crosslinked and substituted starches

“…4 Starches from different sources vary mainly in their chemical structure and composition (amylose-to-amylopectin ratio), which strongly affects their gel-forming properties and their potential use as sustained release matrices. Amylose is an essentially linear polymer and tends to reassociate to form an insoluble network structure, 5 which leads to poor water holding capacity and unstable gel matrices in its native form. In contrast, amylopectin is a highly branched and large molecular weight polymer, which is less prone to reassociation and thus shows a better water holding capacity.…”