Electroacoustic determination of size and charge of sunflower oil-in-wateremulsions made by high-pressure homogenising

Determination of the particle size and zeta potential of emulsions formed b y high-pressure homogenisation has been made by electro acoustics using a f low-through version of an AcoustoSizer. The sunflower oil-in-water emulsion s were formed by passing the stirred oil-water mixture through a homogenise r in the presence of sodium dodecyl sulfate (SDS) at natural pH (6-7). The number of passages, the passing temperature and the volume fraction of oil are major factors influencing the final particle size, while the zeta poten tial is only slightly affected. The electroacoustic technique makes it poss ible to measure directly the size and zeta potential of the emulsion drople ts from 2 to 50% oil volume fraction. The zeta potential was similar to -95 mV and the median particle size, measured after 15 passages, decreased fro m 0.76 mum (2% v/v) to 0.23 mum (50% v/v) at 30 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.