Color changes in hydrocarbon oil-in-water emulsions caused by Ostwald ripening.
The influence of Ostwald ripening on the optical properties of hydrocarbon oil-in-water emulsions stabilized by sodium dodecyl sulfate was investigated. The droplet size, spectral reflectance, and tristimulus color coordinates (L, a, and b) of a series of n-hexadecane and n-octadecane oil-in-water emulsions were measured in the presence and absence of a water-soluble red dye (FD&C Red No. 40). The droplets grew more rapidly in the emulsion containing n-hexadecane than in the emulsion containing n-octadecane because of the higher solubility of n-hexadecane molecules in the aqueous phase. Ostwald ripening caused appreciable changes in n-hexadecane emulsion spectral reflectance and color L, a, and b values due to the growth of emulsion droplets. L, a, and b color values and spectral reflectances of n-octadecane emulsions did not significantly change during the course of the experiment. The results were explained in terms of Ostwald ripening theory and a previously described light scattering theory. The model enables emulsion manufacturers to predict color changes in oil-in-water emulsions that exhibit transcondensational ripening.
Weiss
J
J
Colloidal and Interfacial Food Science Laboratory, Department of Food Science and Technology, The University of Tennessee, 2605 River Road, Knoxville, Tennessee 37996, USA. jweiss1@utk.edu
McClements
D J
DJ
D003116:Color; D004655:Emulsions / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry*; D008027:Light; D009821:Oils; D010316:Particle Size; D012542:Scattering, Radiation; D012967:Sodium Dodecyl Sulfate; D012995:Solubility; D014867:Water
D004655:Emulsions; D006838:Hydrocarbons; D009821:Oils; D014867:Water; D012967:Sodium Dodecyl Sulfate