A commercial ultrasonic probe was used to study emulsification of an o/w system (5 wt% soybean oil stabilised with 1 wt% Tween 80 in water). Two different sets of experiments were performed. Firstly, we investigated the effect of power, duty cycle and ultrasound time on the production of an oil-in-water emulsion from a coarse pre-emulsion mix. The droplets reached a stable size (0.7 microm) within 5 min independent of the power and duty cycle used. Secondly, the mechanism of emulsification was studied by observing the emulsification process at an oil-water interface (no pre-mix) with a high-speed camera. Transient cavitation is thought to be responsible for acoustic emulsification; however there have been no measurements to relate the transient cavitation zone to the production of an emulsion. It has already been shown that the transient cavitation in probe systems is directly under the probe tip. High-speed observations showed that an emulsion could only be obtained if the interface was within a few millimetres of the probe tip. These results strongly suggest that the transient cavitation zone is responsible for the acoustic emulsification of oil.

Capillary electrophoresis has been used to characterize samples of the copolymeric anionic polysaccharides homo- and rhamno-galacturonan (HG and RGI, respectively). In the case of HG, the ratios of the two component sugar residues, galacturonic acid and its methylesterified analogue, have been controlled chemically to produce samples comprised of varying degrees of methylesterification (DM). The mapping of the measured electrophoretic mobilities to the biopolymer charge density has been considered in some detail and for HG substrates with random intramolecular patterns of methylesterification it is shown that the experimentally extracted intermolecular DM distribution agrees well with the predictions of calculations based on the binomial theorem. This demonstrates that the intermolecular distribution of the methylesterification of pectin samples contains information on the intramolecular pattern by virtue of the fact that they are both manifestations of the same statistical process.