So, the rheological properties of concentrate emulsions are
strongly dependent on the -carrageenan/gelatin w/w ratio, Z, in
an aqueous phase. Increasing this ratio (i.e. increasing the polysaccharide
concentration) resulted in a decrease in the yield stress,
viscosity, and storage modulus. Moreover, as discussed above
(Fig. 4), when exceeding a certain threshold (Z > 0.1 gcar/ggel), emulsions
become partly unstable for coalescence and the emulsion
morphology sharply changes (Fig. 5).
Meanwhile, the behaviour of all emulsions under investigation
is qualitatively similar. All of them are viscoelastic media
with a clearly expressed (linear) domain of solid-like behaviour.
In this regard, we should apply to comparison of data presented
in Figs. 6 and 9. In Fig. 6, there is a domain of apparent maximum
quasi-Newtonian viscosity, although this behaviour is not evident
for emulsions stabilised by gelatin only (without -carrageenan).
Therefore, there is a contradiction between solid-like behaviour at
low deformation amplitudes (and correspondingly, low stresses)
and the possibility of flow (as seems evident from Fig. 6). Such a
contradiction was observedin[46] andexplainedby the time factor,
i.e. so-called thixotropic/rheopectic effects. Later, similar effects
were described for many multi-component materials [47–50] and
considered their general peculiarities.