Ordered conformation of xanthan in solutions and "weak gels": single helix, double helix – or both?

Loading...
Thumbnail Image
Files
4344.pdf(2.68 MB)
Accepted Version
Date
2017-11-24
Authors
Morris, Edwin R.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier Ltd
Research Projects
Organizational Units
Journal Issue
Abstract
During the progress of xanthan from a recent discovery to its present status as a well-established food hydrocolloid, some investigations have indicated that the ordered structure, which underlies most of the practical applications of xanthan, is a single helix stabilised by ordered packing of sidechains along the polymer backbone, giving first-order kinetics for the disorderâ order transition. Others favoured a coaxial double helix, whose formation causes a doubling of molecular weight and mass per unit length. It is proposed here that both interpretations are correct, and that ordering is a 2-stage process: formation of single helices followed, under favourable conditions, by enthalpically-driven conversion to coaxial double helices. Comparison of recent evidence from atomic force microscopy with models from analysis of X-ray fibre diffraction data suggests that the most likely coaxial arrangement is an antiparallel 51 double helix.
Description
Keywords
Xanthan , Conformation , Single helix , Double helix , Light scattering , Optical rotation
Citation
Morris, E. R. (2017) 'Ordered conformation of xanthan in solutions and "weak gels": single helix, double helix – or both?', Food Hydrocolloids, 86, pp. 18-25. doi:10.1016/j.foodhyd.2017.11.036