Physicochemical characterization of black seed oil-milk emulsions through ultrasonication

The ultrasonic formation of stable emulsions of a bioactive material, black seed oil, in skim milk was investigated. The incorporation of 7% of black seed oil in pasteurised homogenized skim milk (PHSM) using 20 kHz high intensity ultrasound was successfully achieved. The effect of sonication time and acoustic power on the emulsion stability was studied. A minimum process time of 8 min at an applied acoustic power of 100 W was sufficient to produce emulsion droplets stable for at least 8 days upon storage at 4 ± 2 °C, which was confirmed through creaming stability, particle size, rheology and color analysis. Partially denatured whey proteins may provide stability to the emulsion droplets and in addition to the cavitation effects of ultrasound are responsible for the production of smaller sized emulsion droplets.