Taking into account the molecular weight of used gelatin is
100,000 Da and that of -carrageenan is equal to 680,000 Da, it
is possible to evaluate the -carrageenan/gelatin “molar” ratio, Z
(Fig. 1) in the aqueous mixtures. A simple calculation shows that
this ratio in the stoichiometric complex (at the maximal optical
density, Fig. 1) is 0.10 molcar/molgel.
A decrease in the optical density following a further increase in
the -carrageenan concentration (i.e. -carrageenan/gelatin ratio,
Z or Z) is related to the formation of non-stoichiometric complexes
with varying content. In theory, such a dependence on Z is typical
of interpolymer complex formation [42] and also polyelectrolyte
gelatin–-carrageenan complexes [29].