The operation of the food freeze dryer is relatively simple, and the operation steps can be divided into three steps: food pretreatment, pre-freezing, and vacuum drying.
Step 1. Food pretreatment: Fresh raw materials should be washed and sliced. When slicing, the thickness should be appropriate, and the cutting surface should be perpendicular to the fiber direction, so that the interface movement direction of the ice sublimation interface during freeze-drying is consistent with the fiber direction, so as to improve the drying rate.
Step 2. Pre-freezing: Before packing, put the processed raw materials into the freeze-drying box to cool down the empty box, then put the product into the freeze-drying box for pre-freezing, and freeze at -35°C for 2-4 hours. Freeze the moisture well.
Step 3. Vacuum freeze-drying: when the temperature of the cold trap reaches about -50°C, various parameters of the vacuum freeze-drying machine are set, and vacuum freeze-drying is performed. Freeze-drying is divided into two stages. At the beginning of freeze-drying, the separator is not heated, and heat is provided for the sublimation process through external radiation. Freeze-drying takes about 10 hours. The sublimation-drying stage is basically completed, and the analysis and drying stage is entered. Start the heating program to make the separator. When the temperature reaches 40°C, when the temperature of the material is close to the heating temperature, it means that the material has been freeze-dried, and the freeze-drying operation is ended.
