Kinetic study on the effect of ultrasound on lipase-catalyzed hydrolysis of soy oil: Study of the interfacial area and the initial rates

Comparative studies of lipase-catalyzed hydrolysis of soy oil takes place at the interface between the oil and the aqueous solution in solvent-free system were carried out in shaking bath and in ultrasonic bath. The interfacial area between the oil phase and the aqueous phase influences the rate of hydrolysis. Compared to shaking bath, ultrasonic shaking was found to be a more effective procedure to disperse the oil in water. Larger interfacial area and smaller drop size could be obtained in ultrasonic bath. The initial rate of hydrolysis was increased with the increasing of interfacial area. In ultrasonic bath, the highest initial rate of reaction was obtained with the oil volume fraction of 0.7, which was in accord to the highest interfacial area obtained with the oil volume fraction of 0.7, when the ultrasonic power was 1.64 W/cm2. The higher initial rate of hydrolysis was 161 mol/m3 min. The ultrasonic bath was a useful way to disperse soy oil in water to obtain a larger interfacial area, which caused the higher initial rate of soy oil hydrolysis in the solvent-free system.