When using a freeze dryer to freeze-dry Cordyceps sinensis, its appearance is similar to that of golden needle mushrooms. It is difficult to measure its eutectic point temperature by measuring the change in resistance value. We use the trial method and experimental observation. After physical slice observation, the eutectic point temperature of northern Cordyceps sinensis is about -10~51℃.
In order to ensure that the tissue of Cordyceps sinensis is not damaged, we use the method of quick freezing. First, the shelf temperature in the freeze-drying room is reduced to -20℃, and then the northern Cordyceps sinensis is placed on the shelf in the freeze-drying box. After 1 hour, the shelf temperature reaches -36℃, and the product temperature is -19℃. At this time, the vacuum pump is turned on, the freeze-drying box stops refrigeration, and the water vapor condenser continues to refrigerate.
After 1.5 hours, the freeze-drying box shelf is heated, and its heating speed is controlled until the shelf temperature is close to the product temperature. It is considered that the freeze-drying process is basically completed, and the heating, vacuum pump, and refrigerator are stopped.
The air valve is opened and the Cordyceps sinensis is taken out. The entire freeze-drying process lasts 13 hours. The drying chamber of the FD-2C vacuum freeze dryer is made of aviation acrylic material, which is high-strength and leak-free. It uses an industrial-grade touch screen for simple and convenient operation.
