Solution properties of gellan gum: change in chain stiffness between single- and double-stranded chains.
Nine samples of gellan gum in the sodium form, ranging in weight-average molar mass from 3.47 x 10(4) to 1.15 x 10(5) at 40 degrees C, were investigated by static and dynamic light scattering and viscometry in 25 mM aqueous NaCl both at 40 and at 25 degrees C. The ratios of the molar mass at 25 degrees C (in the ordered state) to that at 40 degrees C (in the disordered state) were in the range of 1.99 to 2.07, supporting the scheme of the conformational transition of gellan gum between a disassociated single chain and an associated chain composed of two molecules. Focusing on the effects of polydispersity, the intrinsic viscosities, radii of gyration, and hydrodynamic radii were analyzed on the basis of unperturbed wormlike chain models. The persistence lengths were evaluated as 9.4 nm at 40 degrees C and 98 nm at 25 degrees C.
Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, Sumiyoshi, Osaka 558-8585, Japan. rheo@oct.zaq.ne.jp
Rheo
R
Takahashi
Hiroshi
H
Tokunou
Kenji
K
Kubota
Etsuyo
E
Ogawa
Tatsuo
T
Oida
Tokuzo
T
Kawase
Katsuyoshi
K
Nishinari
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D008027:Light; D008969:Molecular Sequence Data; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012542:Scattering, Radiation; D012996:Solutions; D014783:Viscosity
D011135:Polysaccharides, Bacterial; D012996:Solutions; C048288:gellan gum