So far, some techniques have been proposed as a method for drying substances prone to thermal denaturation at low temperatures. For example, the following methods are proposed for Pinzheng drying. Specifically, the depressurized superheated steam is introduced into the main body of the drying device that maintains the pressure reduction, and the food and other dry substances that are prone to thermal denaturation in the main body of the drying device are dried through decompression and overheating.

　　However, in this method, the placed object to be dried contacts with the depressurized superheated steam and carries out heat exchange. Therefore, it is difficult to ensure a large evaporative heating surface when the dried material is liquid raw material. In order to ensure a large evaporative heating surface, there is a problem of large-scale equipment.

　　In addition, the following methods are proposed by the Pinzheng drying chicken essence production line. Specifically, the spray drying device body is filled with flowing particles such as glass beads, and drying objects such as heat denatured foods, and the superheated steam decompression body after decompression is introduced into the spray drying device. The object to be dried and the depressurized superheated steam contact each other in a fluidized state. In this way, the object to be dried is dried.

　　However, in this method, it is also necessary to mix the drying object with the fluidizing particles in the main body of the spray drying device to form a flowing state, so it is inappropriate to use this method as a drying method to crush liquid raw materials into substances that are easily subject to thermal denaturation.