Droplet size determination in food emulsions: comparison of ultrasonic and light scattering methods

Ultrasonic velocity and attenuation spectra (1–5 MHz) were measured for a series of corn-oil-in-water emulsions (20 wt% oil in 2 wt% polyoxyethylene sorbitan monolaurate) with a range of different mean droplet diameters (0.5–1.5 μm). Multiple scattering theory was used to calculate mean diameters for each emulsion from both spectra. Droplet size was also determined using two commercial light scattering instruments. All techniques showed the same general trend of decreased size with increased degree of homogenization but there was only limited quantitative agreement between the various measurement techniques.