文摘
The influence of guar gum and xanthan gum on the creaming of 10% oil in water emulsions hasbeen investigated. The presence of very low concentrations of the polysaccharides (typically< ~0.075%) was found to induce depletion flocculation of the emulsion droplets and increased therate of creaming. However, at higher polysaccharide concentrations (typically > ~0.1%) the creamingrate was reduced due to the increased viscosity of the aqueous phase. For most systems a delayperiod was noted before creaming started, which was found to be dependent on the zero shearviscosity of the continuous phase and independent of polysaccharide type. The delay period increasedsignificantly at zero shear viscosities approaching 1 Pa s. A mathematical model has been used tofit the creaming rate profiles and a simple exponential relationship obtained between delay time andpolysaccharide concentration.Keywords: Emulsion stability; depletion flocculation; delay time for creaming; xanthan gum; guargum; oil in water emulsions