The processing of healthy foods remains a challenge and any technology with the ability to tailor the physical properties of new materials is in demand. High-intensity ultrasound (HIU) has been identified as a useful processing technique for such activities particularly for edible lipids. HIU has been known to alter the crystallisation kinetics and in turn the resultant physicochemical properties for specific food applications. The role of cavitation dynamics during treatment of oils with HIU is of interest, with the knowledge gained allowing for insight into the complex and still undefined mechanism of action. To this end, the crystallisation kinetics of an edible lipid were investigated in the presence of several distinctly different cavitation conditions. Several cavitation clusters, including a bifurcated streamer (BiS), located on the surface of a piston-like emitter (PLE) were studied, each generated by a specific ultrasonic power level. Only samples crystallised at a low supercooling (ΔTSC) value display significant differences in induction time for each of the selected HIU powers, at least 5 minutes earlier than without exposure to HIU. Substantially better energy efficiencies were seen for the BiS regime (ΔTSC = 5 °C) which coincided with maximal crystal growth rates. An increase in melting enthalpy and elastic modulus is reported in the presence of HIU for all crystallisation temperatures, this effect is larger overall with increasing ultrasonic power. In addition, sonicated samples in the presence of the BiS event were composed of fewer smaller crystals compared to higher HIU powers after 60 minutes at 30 °C. Bubble dynamics recorded during a 10 s sonication period exhibited a greater acoustic attenuation effect for the highest ultrasonic power (75 W). The results suggest that the dynamics of the cluster and the presence of the BiS event are important in terms of energy efficiency and the physical properties of the crystallised lipid material.

Solid fat content (SFC) measurements collected using NMR Minispec mq20 series (Bruker, California, USA). This data is fitted to the Gompertz kinetics model which yields the induction time for crystallisation (λ) and the maximal crystal growth rate (μ) Hardness data collected using a Texture Analyser (model TA, XT Plus, Texture Technologies Corp., Scarsdale, NY, USA). Melting behaviour analysed using differential scanning calorimeter (DSC-TA Instruments, New Castle, DE, USA). Viscoelastic properties measured using magnetic bearing rheometer (model AR-G2, TA Instruments, New Castle, DE, USA). Crystal microstructure was determined using a polarised light microscope (PLM-Olympus BX 41, Tokyo, Japan) fitted with a digital camera (Infinity 2, Lumenera Scientific, Ottawa, Canada). Hydrophone data collected using an oscilloscope or a DAQ card and was processed using VB2010 software utilising NI Measurement studio.

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Funded under Agriculture and Food Research Initiative (AFRI) Grant No. 2017-67017-26476