The characterization of small emulsion droplets made from milk proteins and triglyceride oil

Measurements have been made of the light scattering properties of emulsion droplets produced using a Microfluidizer. The droplet size distributions were measured by both Integrated Light Scattering (ILS) over a wide range of scattering angles, and by Dynamic Light Scattering (DLS) at a fixed angle of 90 degrees. From the former, it was possible to derive number distributions, whereas the latter was used to give intensity distributions of the droplets. The calculated distributions from light scattering were also compared with samples studied by transmission electron microscopy. A range of samples was studied, including whole milks, and emulsions prepared from soya oil and stabilized by sodium caseinate; fractions containing the smaller droplets from these emulsions were also collected and studied. The results confirmed that it was possible to isolate a population of small (< 100 nm) particles from microfluidized milk or from the emulsions; larger particles were also present. Both ILS and electron microscopy confirmed these results. DLS also confirmed the presence of the small particles in the emulsions, but principally was useful in the analysis of the separated fractions. To improve the sensitivity of the method, it is necessary to use non-linear channel times in DLS experiments.