A novel global hydrodynamic analysis of the molecular flexibility of the dietary fibre polysaccharide konjac glucomannan

• Published in: Food hydrocolloids Vol. 23; no. 7; pp. 1910 - 1917
• Main Authors: Kök, M. Samil, Abdelhameed, Ali S., Ang, Shirley, Morris, Gordon A., Harding, Stephen E.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-10-2009; Elsevier
• Subjects: Biological and medical sciences; Coefficients; Estimates; Flexibility; Fluid dynamics; Fluid flow; Food additives; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Intrinsic viscosity; Konjac glucomannan; Molar mass; Molecular weight; Persistence length; Sedimentation; Semi-flexible coil; Viscosity; Persistence length; Konjac glucomannan; Semi-flexible coil; Molar mass; Intrinsic viscosity; Persistence; Polysaccharide
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2009.02.002

Konjac glucomannans have been widely considered in health food products although their hydrodynamic properties have been poorly understood. The weight-average molecular weight (
M
w); sedimentation coefficient (
s
0
20,w) and intrinsic viscosities ([
η]) have been estimated for five different preparations. The decrease in both intrinsic viscosity and sedimentation coefficient with molecular weight enables the estimation of molecular flexibility in terms of persistence length (
L
p) using the traditional Bohdanecky–Bushin and Yamakawa–Fujii analyses for intrinsic viscosity and sedimentation data respectively. However, this requires an assumption of the mass per unit length
M
L. Advantage can now be taken of a recent development in data interpretation which allows the estimation of
L
p from combined intrinsic viscosity and sedimentation coefficient data and also an estimate for
M
L. Using this “global” procedure an estimate of (13
±
1)
nm is found for
L
p and a value of (330
±
10)
g
mol
−1
nm
−1 for
M
L.
The value for
L
p suggests a molecule of considerable flexibility, comparable to galactomannans (
L
p
∼
8–10
nm) but not as flexible as pullulan (
L
p
∼
1–2
nm).