Development of high-quality cryopreservation technique of food by active control of ice formation utilizing ultrasonic irradiation

主动控制结晶的方法是一种很有前途的食品低温保存技术。本课题的目的是研究超声波辐照对食品冷冻过程中结冰的影响。在实验中，琼脂凝胶或纯水在各种超声照射方式下冷冻。结果表明，在高强度下施加超声，可使过冷态得到释放，使超声空化效应增强。另一方面，在低强度下施加超声会导致成核温度的延迟。在初始过冷度一定的情况下，随着超声功率的增大，冰结构尺寸减小。在此基础上，讨论了超声辐照下生物组织超声结晶的机理。

A method to actively controlling crystallization is one of promising technique for cryopreservation of food. The object of this project is to study the effects of ultrasonic irradiation on ice formation during freezing of food. In the experiments, agar gel or pure water was frozen under various irradiation methods of ultrasound. It was found that the supercooling state was released by applying ultrasound at high intensity level, since ultrasonic cavitation effects augmented. On the other hand, a delay in the nucleation temperature was caused by applying ultrasound at low intensity level. Secondly, ice structure size decreased with increasing ultrasonic power under given initial-supercooling degree. Summarizing these results, the mechanism of sonocrystalization in biological tissue was discussed in relation to method of ultrasonic irradiation.