Improved extraction of carrageenan from red seaweed () using ultrasound-assisted methods and evaluation of the yield, physicochemical properties and functional groups.

Red seaweed , an underexploited algae species, was used as a potential source for the obtaining of carrageenan. Seaweed was treated under alkaline conditions using ultrasound alone or combined with conventional procedures, to improve the yield extraction. Color, syneresis behavior, water retention capacity, and functional groups of the gelling and non-gelling fractions of carrageenan were determined; these properties were compared with those of commercial carrageenans named A and B. Ultrasound alone or with heat significantly ( < 0.05) increased the yield extraction up to 41-45% and influenced color parameters, in comparison with conventional treatments. Functional groups and , and alginates, were confirmed in both carrageenan fractions. Syneresis behavior was well fitted to a third-degree polynomial equation within days 1 to 6, after which, it reached a plateau. While, the use of ultrasound at room temperature gave carrageenan properties more similar to those of the commercial carrageenan type A.