Starch fractions as examples for non-randomly branched macromolecules. 1. Dimensional properties

Abstract

Starch is well-known as a blend consisting of highly branched amylopectin and much smaller linear amylose. At a low amylose content the light scattering behavior is dominated by the amylopectin part. Applying a recent description by Fox and Robyt, a series of different molecular weights were prepared by acid degradation of potato starch. The obtained samples were characterized by static-dynamic light scattering and viscometry in a solution of 0.5 N NaOH. The results are compared with data from literature for amylose. The applicability of scaling relationships between exponents is checked. Determination of contraction factors allows evaluation of the branching density. These results are in good agreement with the theoretical model of ABC polycondensation. A comparison between the branching density obtained by LS measurements (0.016) and the branching density determined by NMR and enzymatical techniques (0.04) is made. The observed discrepancy is explained by a modified model of heterogeneously branched amylopectin. The approximate nature of the ABC model is also displayed by deviations of the experimental (= Rg/Rh) parameters from those predicted by the model.

Influence of extraction conditions on properties of seed xyloglucan

“…Similar values were obtained by Bello-Pérez et al [32] for amylopectin and normal corn starch and by Wang et al [33] for soybean polysaccharides. Considering the average molar mass (M W ), determined by HPSEC-MALLS, the index was found to decrease with increasing molecular mass as observed by Galinsky and Burchard [34] for starch. Their decrease, after longer extraction times, could indicate self-association of xyloglucans resulting in a more globular shape.…”

Microwave-assisted solubilization and solution properties of hyperbranched polysaccharide

“…A common technique involves the use of solvent such as alkali or LiCl/Me 2 SO to break the intermolecular hydrogen bonds of the polysaccharides, resulting in dissolution. 8,9 However, such solvent systems are not applicable in bioactivity assays. Additionally, chemical modifications have been used to improve the solubility of polysaccharides.…”

Molar mass and solution conformation of branched α(1→4), α(1→6) Glucans. Part I: Glycogens in water

“…The degree of branching of a hyper-branched macromolecule can be estimated from the shrinking factors (Ioan et al, 1999, Freire & Garcìa de la Torre, 1992Burchard et al, 1980;Zimm & Stockmayer, 1949;Galinsky & Burchard, 1995;Ioan, Aberle & Burchard, 2001) (Figure 4) g, g' and h.…”