PhD Studentship – Understanding bubble dynamics in sonicated edible lipids to improve their physicochemical properties

High intensity ultrasound (HIU) or sonication has been exploited as a processing tool to change the physical properties of lipids. The materials studied are diverse and include anhydrous milk fat, palm kernel oil, palm oil, and all-purpose shortenings. HIU can alter the crystallization kinetics of some lipids, creating smaller crystals and generating a crystalline network that is harder, more viscous and with a greater elasticity. However, no single sonication condition will work for all systems and the use of this technology in lipids with low levels of saturation remains a challenge. While the beneficial effects of HIU are clear, sonication and process conditions, such as acoustic power levels and crystallization temperatures, must be optimized using a trial-and-error approach for each lipid system. These optimizations are typically conducted empirically by systematically changing the processing parameters (e.g. the sound source geometry, acoustic exposure duration, acoustic power levels, and crystallization temperatures etc.) to identify useful combinations of variables. This technically difficult and time-consuming approach is used because there is minimal understanding of the fundamental events associated with lipid sonocrystallization. This gap in knowledge limits the possibilities for using HIU technology on an industrial scale.
The aim of the project is to use a multidisciplinary strategy that combines analytical physical measurements, engineering, tailored lipid design, and food science to understand bubble dynamics in sonicated lipids and relate these events to crystallization kinetics and physicochemical properties of the material. In order to exploit HIU we aim to characterise the dynamics of bubble behaviour in oils. This aim will be achieved using a set of novel analytical characterisation techniques employed within the unusual environments generated around a high intensity ultrasonic source. In this complex environment, novel Coulter counter experiments combined with high-speed imaging, acoustic emission analysis and optical scattering techniques will be undertaken. The knowledge gained by this approach, in combination with the expertise gathered from collaborators in the project, will simplify the optimization of processing conditions needed to tailor the physical properties of lipids and hence improve the ultimate product quality.

The project will also involve close collaboration with colleagues in the US (Utah State University and University of Georgia). This collaborative section of the project will involve the student visiting the US for a short period in order to meet the goals of the project through the exchange of ideas and technical knowledge.