Comments on viscosity enhancement and depletion flocculation by polysaccharides

Polysaccharides are added to oil-in-water emulsions to enhance the viscosit y of the aqueous phase, which modifies their texture and retards droplet cr eaming. Nevertheless, at certain concentrations polysaccharides have been s hown to accelerate creaming instability by promoting droplet flocculation t hrough a depletion mechanism. This paper examines the relationship between the molecular structure of polysaccharides and their ability to enhance the viscosity of aqueous phases and to induce depletion flocculation in emulsi ons. A theoretical phase diagram is developed to relate the creaming instab ility caused by polysaccharides to their molecular structure and concentrat ion. (C) 2000 Elsevier Science Ltd. All rights reserved.