Addition of sugars influences color of oil-in-water emulsions

The influence of glucose, fructose, lactose, and glycerol on the color and appearance of surfactant-stabilized oil-in-water emulsions containing a red dye was investigated. A stabilized (Tween-20) oil-in-water emulsion was di luted into sugar. solutions to give a range of oil droplet and sugar concen trations. Tristimulus coordinates (L, a, b) and reflectance spectra were me asured using a spectrophotometer. With increasing sugar concentration, refl ectance spectra shifted to lower reflectance values. Tristimulus coordinate s were reduced by approximately 50% for emulsions containing high concentra tions of sugar. Adding fructose to emulsions reduced L a, b values more sig nificantly than adding glucose, lactose, or glycerol. Tristimulus coordinat es remained constant when the temperature was raised from 20 to 80 degreesC . The experimental results were explained in terms of the change of relativ e refractive index at the water-oil interface. The results have important i mplications for the food industry as they offer a new means to control and optimize the color of food emulsions.