Abstract
A method to actively controlling crystallization is one of promising technique for cryopreservation. The object of this paper is to study the effects of ultrasonic irradiation on ice formation during freezing of biological materials. In the experiments, potato tissue was frozen under irradiation of ultrasound at frequency of 28kHz. Firstly, it was found that ultrasound enhanced the freezing rate. Secondary, the microscopic observation using Cryo-SEM suggested that mechanical damage of the tissue due to extracellular ice formation was reduced by ultrasonic irradiation. However, through impedance analysis, the Cole-Cole arc disappeared regardless of ultrasonic irradiation. Therefore, the effects of ultrasonic irradiation on freezing damage did not made clear quantitatively.
