The G- and M- units are joined together in one of three blocks: GG... , MM... , and MG.... These are illustrated in Figure 5. The proportion, distribution, and length of these blocks determine the chemical and physical properties of the alginate molecules.
The chemical composition of alginate varies according to seaweed species and even within different parts of the same plant. As with all products produced from natural resource, alginate properties are subject to seasonal variations. By selecting raw materials with varying but known properties, FMC BioPolymer is able to manufacture alginates with consistent properties in a wide range of grades.