Conventional and alternative technologies for the extraction of algal polysaccharides

Abstract: Alginates, agar and carrageenan are the main commercial water-extracted polysaccharides sourced from brown and red marine algae. These phycocolloids exhibit high viscosity, and stabilizing, emulsifying and unique gelling properties. Agar and carrageenan form thermoreversible gels while alginates form ionic non-thermoreversible gels; therefore they play an irreplaceable role in foods, pharmaceuticals and biotechnology. The phycocolloid industry uses seaweeds from different parts of the world, and phycocolloid production amounts to 86 100 tons annually; equivalent to US$ 1018 million. In this chapter we describe the conventional processes adopted in most factories for extracting and processing alginates, agar and carrageenan, and discuss the use of new eco-friendly extraction processes.