We report confocal microscopy observations of the spatial distribution of monodisperse charge-stabilized colloidal particles (amphoteric polystyrene latex) incorporated within a spinodal-type phase-separating system of mixed biopolymers (gelatin + oxidized starch). Images from samples aged at 40 degrees C demonstrate a strong tendency for the added particles to accumulate at the liquid-liquid interface and to influence the rate of coarsening of the complex bicontinuous microstructure. Large variations in the local curvature of particle-rich interfacial regions are suggestive of a liquid-liquid boundary that is substantially viscoelastic.

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Using confocal microscopy and small-deformation rheology, we demonstrate the formation of stable thermoreversible gelatin-based gels with colloidal fractal-type microstructure. The opaque particle gels were made by cooling of transparent mixed aqueous solutions of gelatin (1-3 wt %) and starch (7 wt %) from 40 to 24 degrees C. The mechanism involves starch-induced gelatin self-association into phase-separated gelatin-rich microgel particles, followed by diffusion-limited cluster aggregation into a particle gel network.