Gelation occurs by cross-linking of the uronic acids with divalent
cations, such as Ca2+. Calcium has found greatest popularity as the divalent ion for gel formation because its salts are cheap, readily available and non-toxic The primary mechanism of this gelation
involves extended chain sequences which adapt a regular
two-fold conformation and dimerize with specific chelation of
Ca2+, the so-called ‘egg-box’ structure