What term describes the reversible migration of droplets to the surface of an emulsion, forming a cream layer?

• A. Creaming
• B. Flocculation
• C. Coalescence
• D. Breaking

Answer: (A)

Creaming is the reversible migration of droplets to the surface of an emulsion, forming a cream layer. This happens because there is a density difference between the dispersed droplets and the continuous phase, so gravity drives the droplets to rise (or sink) until a distinct layer forms at the top. Because this movement is not destroying the droplets, the process can be reversed by stirring or shaking to redisperse the droplets. It’s different from flocculation, where droplets cluster together but remain dispersed within the same phase; and from coalescence, where droplets fuse to form larger droplets, potentially leading to emulsion failure. Breaking refers to the complete separation into separate liquid phases. Factors like larger droplet size and greater density difference speed creaming, while higher viscosity of the continuous phase slows it down.