Rheological Properties of Alginate Gel

Abstract

The alginate is an anionic polysaccharide which is composed of 1-4 linked β-D-mannuronic acid (M) and 1-4 linked α-L-guluronic acid (G). The mannuronic acid/guluronic acid ratio of an alginate molecule effects strongly on the polymer concentration at the gel point in the alginate-acetic acid aqueous solution system. The G-rich alginate forms a gel at lower polymer concentration. This is attributed to the fact that the sequence of guluronic parts is stiffer than that of mannuronic parts. On the respect of gella-tion by introducing divalent metal ions, the salt concentration required for gelation of alginate aqueous solution increases in the order of SrCl2 Ca2+ >Mg2+, and that the G-rich alginate has a higher affinity for divalent metal ions. The gel structures formed by introducing CaCl2 or SrCl2 were also studied in terms of fractal structure using small angle X-ray scattering measurements. © 1994, The Chemical Society of Japan. All rights reserved.