Exploring the frontiers of colloidal behaviour where polymers and particles meet

Two simple representations are commonly invoked to interpret the physicochemical properties of colloidal systems: the rigid particle model and the flexible polymer model. This article compares the essential features of these two ideal descriptions of the main functional entities involved in the stabilization of food suspensions, emulsions and foams. Attention is directed towards the factors that affect the structural and mechanical properties of adsorbed layers and the influence of nanoparticles and polymers on colloidal interaction forces between the surfaces of microparticles and emulsion droplets. In systems containing mixtures of particles and polymers, the various species may remain dispersed, or they may become associated into complexes, aggregates and networks. Adsorbed protein layers may be described using a polymer-like model (casein) or a particle-like model (hydrophobin), or a kind of composite representation (most globular proteins). Certain important food particles, like casein micelles and swollen starch granules, are themselves composed of interacting polymeric building blocks, and they exhibit mechanistic behaviour that deviates substantially from both simple solid spheres and simple molecular polymers. One particular type of hybrid particle polymer entity that is attracting current interest from many researchers in soft matter physics and food colloid science is the responsive microgel. (C) 2015 Elsevier Ltd. All rights reserved.