ABSTRACT
Alginic acid was first discovered by Stanford and recognized as
the structural component of marine brown algae (Phaeophyceae) [136] where it constitutes, as an insoluble mixture of calcium,
magnesium, potassium and sodium salts [62], up to 40% of the
dry matter. In the first half of the twentieth century, the repeating
units constituting the polysaccharide backbone were identified
with mannuronic and guluronic acids [7, 47, 120]. The content
of the two different uronic groups in alginate samples was found
to vary over a wide range depending on their source. Nowadays,
to underline the chemical inhomogeneity of this polysaccharide,
the term alginate is used to describe a family of polysaccharides
[113] produced by brown algae and bacteria. In seaweeds, alginates
contribute the strength and flexibility of the plant. Indeed, alginates
have the same morphophysiological properties in brown algae as
those of cellulose and pectins in terrestrial plants [38]. The large-
scale production of alginates is exclusively based on the harvesting
of brown seaweeds belonging to the family of Laminaria (of the species hyperborea, digitata, japonica), to Macrocystis pyrifera, and to Durvillea antarctica. Alginate composition depends on the seasonal and growth conditions as well as on the parts of the plant
that the alginate is isolated from [3, 73].
