K. Demetriades et Dj. Mcclements, INFLUENCE OF DEXTRAN SULFATE AND NACL ON THE FLOCCULATION OF OIL-IN-WATER EMULSIONS STABILIZED BY A NONIONIC SURFACTANT, Journal of agricultural and food chemistry, 46(10), 1998, pp. 3929-3935
The creaming stability and viscosity of 10 wt % soybean oil-in-water e
mulsions stabilized by Tween 20 were monitored as a function of 500 kD
a dextran sulfate (DS) concentration (0-5 wt %) and NaCl concentration
(0-1 wt %). In the absence of salt, DS increased the apparent viscosi
ty of the emulsions and promoted droplet flocculation above a critical
concentration (CFC similar to 0.08 wt % DS). Above the CFC, the cream
ing rate decreased with increasing DS because of the enhanced viscosit
y of the continuous phase. The addition of salt decreased the apparent
viscosity of emulsions, increased the CFC, and increased the creaming
rate above the CFC. These results can be explained by the reduction i
n the effective radius of DS molecules due to electrostatic screening
by the salt. Emulsions with specific physicochemical properties can be
developed by carefully controlling salt and biopolymer concentration.