Bubble and Crystal Formation in Lipid Systems During High‐Intensity Insonation

The objective of the present research was to monitor bubble and crystal formation in lipids during high-intensity insonation. High-intensity ultrasound was generated with a 20-kHz probe. Bubble and crystal formations were recorded using a low-intensity ultrasound spectrometer operating at 1 MHz central frequency. Bubble formation was monitored in soybean oil (SBO) during insonation for different time periods (5, 10 and 60 s) and at different temperatures (22, 24, 26, 28, and 30 °C). Ultrasound attenuation due to the presence of bubbles was observed in all conditions tested. Attenuation increased with temperature and at intermediate frequencies (1 MHz). In addition, the presence of bubbles was detected after insonation was stopped, particularly for SBO sonicated for 60 s at 30 °C. Low-intensity ultrasound spectroscopy was used to monitor the crystallization behavior of interesterified SBO. The acoustic velocity increased during crystallization, but significantly decreased during insonation.