On the physicochemical properties of gellan gum

Abstract

This paper concerns the behavior in dilute and demidilute solutions of deacetylated gellan. The conformational transition, controlled by temperature and ionic strength, is investigated. It corresponds to a double-helix single-chain transition. Large ionic selectivity is observed in the helical conformation th at controls the degree of aggregation upon gelation. Potentiometry and conductivity measurements are interpreted in terms of the Manning polyelectrolyte theory in the sol state.

Application of cross‐flow filtration for determining the solubility of iron species in open ocean seawater

“…Analysis of recent complexation data for 2kDG indicate that it would not be expected to retain Fe in solution under seawater conditions due to the strong interactions with Ca 2+ . Phytagel (Gellan Gum; Miyoshi et al 1996;Nishinari 1999) is a sugar-like macromolecule with a mean molecular weight of ~490 kDa (Milas et al 1990) and has been found previously to bind Th(IV) (Quigley et al 2002) in seawater. Thus we anticipated only a trace amount of 55 Fe would pass through the membrane, due to the high molar mass of the ligand, however we surprisingly measured a high concentration (c P = 9.54 nM).…”

Importance of acid polysaccharides for 234Th complexation to marine organic matter

“…7d). The intrinsic pKa of gellan gum is 3.06, although the apparent pKa increases as a function of ionic strength, and the conformation of gellan goes from a two-coil coiled aggregate in solution to a doublehelix gel with increasing ionic strength (Milas et al 1990). Conformational changes during the radiolabeling of gellan gum, i.e., gel formation, could affect the isoelectric focusing results of this polysaccharide.…”

Unassociated Molecular Chains in Physically Crosslinked Gellan Gels

“…[3][4][5][6][7][8][9][10][11][12][13][14][15][16] The gelation of gellan is remarkably enhanced by the addition of cations in aqueous solutions, since the gellan molecules possess carboxyl groups in the repeating unit. 11,12 Potassium, rubidium and cesium ions are categorized as gel-promoting cations.…”

“…The coil-helix transition temperature increases with increasing concentration of added salt. [9][10][11] Double helix formations and subsequent lateral association of the double helical molecules may achieve formation of the gellan gel network. It has been reported that gellan gels possess a crosslinking domain composed of associated double helices.…”