Kappa-Carrageenan is a gelling sulphated galactan extracted from red seaweed (typically Gigartina stellata and Chondrus Crispus).
The structure of all carrageenans consists of a strictly alternating masked repeating unit of (1,3)-linked α-D-galactose and (1,4)-linked β-D-galactose.
The α-linked galactose occurs as a 3,6-anhydro unit and the β-linked sugar occurs as the 4-sulphate.