Carrageenans are polysaccharides extracted from red algae and are commonly used as food additives, e.g. as thickening, stabilizing or gelling agent . They are linear polysaccharides and often described by using repeating disaccharide units. These units are composed of a 1,3linked β-D-galactopyranose (G-unit) and a 1,4-linked α-D-galactopyranose (D-unit) or 3,6-anhydro-α-D-galactopyranose (DA-unit). The individual monosaccharide units can be substituted with sulfate groups . The substitution position depends on the type of carrageenan and is usually annotated by adding the position and "S" to the monosaccharide descriptor (e.g. G4S for a 1,3-linked galactose unit which is sulfated at position C4) .