Brown algae, algin

Alginates are a family of polysaccharides mainly extracted by brown algae. Alginate hydrogels are able to store up to 100 times their weight of water, trapped in a network of hydrophilic fibrils. This property accounts for their natural occiurence as water reservoirs in plants of the tidal area [6]. 

The alginic acid content of some of the commercially important brown algae is shown in Table 4. The commercial processes for the production of algin are proprietary (22,23). 

Sodium alginate is the principal brown algae gum, while the red algae are of two practical types ... 

These materials are another polysaccharide. The name derives from its original source, brown algae. The current commercial sources are brown seaweeds such as Laminaria digitata, L. hyperborea, Ascophyllium nodosum and Fucus serratus. Different properties are obtained in alginates from different seaweeds. The sources are rocky coasts in the United States, the United Kingdom, France and Norway. 

D-Mannuronic acid (36) constitutes the major component of alginic acid, the main polysaccharide of the brown algae, in which L-guluronic acid (37) is also found. The ratio of D-mannuronic acid and L-guluronic acid can vary with the algal species, the type of tissue, and the age of the plant. In the case of Laminaria hyperborea, L-guluronic acid is the major component.130... 

Polysaccharides from plants, too, can form gels in water. Pectin is used to help gel jams and fruit preserves. Some polysaccharides are used to thicken foods. Alginic acid, extracted from brown algae, is a linear polymer containing many carboxylic acid groups. The sodium salt is soluble in water and is used as a thickener in the preparation of ice cream and other foods. If a sodium alginate solution is mixed with calcium ion, the polysaccharide pre-... 

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