It is an object of the present invention to provide a refrigeration method for milk or dairy products which can be stored for a long period of time and has high quality and high quality.A storage space for storing stored milk or dairy products, a cooling means for cooling the storage space, an electric field generating means for generating electric fields in the storage space, and an ultrasonic irradiation means for irradiating milk or milk products contained in the storage space to milk or dairy products In the freezer, milk or dairy products are housed in the preserving space, the electric field is generated by the electric field generating means and the ultrasonic wave is irradiated by the ultrasonic wave generating means to cool the milk or milk product by the cooling means and freeze it.本発明は、長期保存が可能で高鮮度で高品質な乳又は乳製品の冷凍方法を提供することを課題とする。 収容された乳又は乳製品を保存する保存空間と、前記保存空間を冷却する冷却手段と、前記保存空間に電場を発生させる電場発生手段と、前記保存空間に収容された乳又は乳製品に超音波を照射する超音波照射手段とを備えた冷凍庫において、乳又は乳製品を前記保存空間に収容し、前記電場発生手段により電場を発生させると共に、前記超音波発生手段により超音波を照射しながら、前記冷却手段により前記乳又は乳製品を冷却して冷凍する。
