ABSTRACT
To fully appreciate the potential of alginate’s gel-forming properties, it helps to understand the chemistry behind gel formation. Regions of guluronate monomers, or G-blocks, in one alginate molecule can be linked to a similar region in another alginate molecule by means of calcium ions or other multivalent cations. The grade of alginate, calcium source and sequestering agents must be matched with the process and overall formulation to develop the final product. Films prepared from sodium alginate are water-soluble, but calcium alginate films are insoluble although they do swell in water. Propylene glycol alginate is compatible with acids and, in many cases, with alkaline-earth metal salts. The solubility of alginates is influenced by the total ionic strength of the solution, the free calcium concentration, and pH of the solvent. The steps involved in biosynthesis of alginate can be divided into four: alginate precursor biosynthesis, polymerization, acetylation and epimerization/transfer, and spread.
