A Review on Thermodynamics and Functional Properties of Complex Coacervates

Complex coacervation is defined as associative interactions between oppositely charged functional groups of proteins and polysaccharides, which on separation, form a phase rich in polymeric compounds in equilibrium with another aqueous phase. So coacervates are macro-ionic hydrated complexes of two charged neutralized bioploymers. Voorn and Overbeek developed the first model on complex coacervation by applying Flory-Huggins theory for random mixing of polyions. Alternatively, Veis and Aryani proposed that initially charged pair of symmetrical aggregates forms, followed by phase separation, for modeling diverse range of aggregates. Physicochemical properties such as pH, ionic strength, ratio of protein to polysaccharide, polysaccharide and protein charge, and molecular weight, mechanical properties (shear force) and temperature affect the formation and stability of coacervates. Improved structural, rheological, interfacial and delivery properties of these complexes than individual biopolymer can be exploited in numerous domains. This article intends to elucidate the salient features of coacervates which may contribute to better understanding of protein-polysaccharide systems, for their application in foods, cosmetics, pharmaceutical, and medicine.