Hydrocolloids acting as emulsifying agents – How do they do it?

We consider the essential compositional and molecular structural features controlling the formation and stabilization of oil-in-water emulsions by hydrocolloid ingredients. The theoretical principles underlying adsorption of polymers and steric stabilization by polymer layers are outlined with particular reference to copolymer morphology and chain branching. These basic concepts are used to interpret at the molecular level the experimental interfacial functionality of three classes of biopolymer emulsifying agents: gum arabic, pectin, and hydrophobically modified starch (OSA starch). Some inferences are made concerning the mechanistic significance of certain generic features in relation to the surface activity and emulsification characteristics of hydrocolloids — the presence of covalently bound protein, the diversity of carbohydrate polymer structure, and the heterogeneity of natural ingredients.