The group of phycocolloid polymers, commonly termed hydrocolloids because they are soluble in water, includes alginates, carrageenans, and agars—and red and brown macroalgae have long been used for the production of such compounds (Carlsson, 2007). These polymers are either located in the cell walls or within the cells where they serve as storage materials (Tseng, 2001).

Hydrocolloids account for the major industrial products derived from algae (Radmer, 1996; Pulz and Gross, 2004). They possess several useful properties for the food industry in thickening agents, forming gels and water-soluble films that are commonly applied to sta­bilize such products as ice cream, toothpaste, and mayonnaise (Tseng, 2001), thus taking ad­vantage of their forming a gel upon cooling (Carlsson, 2007). Each major subgroup is described in further detail in the follow subsections.