ABSTRACT
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their sequential arrangement along the polymer chain may vary widely, depending on the origin of the alginate. The uronic acid residues are distributed along the polymer chain in a pattern of blocks, where homopolymeric blocks of G residues (G-blocks), homopolymeric blocks of M residues (M-blocks), and blocks with alternating sequence of M and G units (MG-blocks) coexist. Thus, the alginate molecule cannot be described by the monomer composition alone. Nuclear magnetic resonance (NMR) characterization of the sequence of M and G residues in the alginate chain is needed in order to calculate average block lengths. It has also been shown by NMR spectroscopy that alginate has no regular repeating unit (Grasdalen et al. 1979, 1981; Grasdalen 1983). The functional properties of alginate are primarily in§uenced by the G content, the average number of Gs in a G-block length, and the molecular weight.
