Potential Effect of Cavitation on the Physical Properties of Interesterified Soybean Oil Using High-Intensity Ultrasound: A Long-Term Storage Study

The objective of this research was to evaluate if cavitation events generated during sonication (20 kHz, 216 mu m amplitude, 10 s) are responsible for changes in physical properties of a fat with low levels of saturated fatty acids and if these changes are maintained during storage. The fat was crystallized at 24 and 34 degrees C and stored at 25 degrees C for up to 24 weeks. An increase in solid fat content and melting enthalpy was observed for sonicated samples crystallized at 34 degrees C and an increase in elasticity was observed for sonicated samples crystallized at 24 degrees C (P< 0.05). Hardness increased in sonicated samples crystallized at 24 and 34 degrees C (P< 0.05) after 60 min of crystallization and after 24 weeks storage. Elasticity of non-sonicated samples crystallized at 24 degrees C decreased (P< 0.05) after storage at 25 degrees C for 48 h while it remained constant in sonicated samples. Sonicated samples had more, and smaller crystals compared to the non-sonicated ones. No significant change was observed in physical properties of sonicated samples crystallized at 24 degrees C and 34 degrees C during the 24 weeks of storage. Sonication at 24 degrees C was less efficient at changing the physical properties of the fat compared to 34 degrees C; however, the number of subharmonic components generated during sonication at these two temperatures was not affected by crystallization temperature. These results suggest that changes in physical properties are associated with secondary effects of sonication such as bubble streamers rather than changes in cluster dynamics.