Carrageenans are sulfated galactans which are extracted from red algae . These polysaccharides consist of alternating 1,3-linked β-D-galactopyranose units (G-unit) and 1,4-linked α-D-galactopyranose units . The D-unit may also be present as 3,6-anhydro-α-D-galactopyranose, which is then referred to as DA-unit. Both the G unit as well as the D/DA-unit can be sulfated at different positions . Depending on the structural composition of the polysaccharide, the sulfate content usually varies between 22 -38 % (w/w) .