General process of freeze-dried food
Different materials need necessary pretreatment before pre-freezing and freeze-drying to make them easy to process. Meat and aquatic product materials need to be tested and screened, cooled and aged, and sliced.
2. Product pre-freezing
The product is subpackaged in suitable containers and pre-frozen below the eutectic point before it can be freeze-dried. The purpose of pre-freezing is to keep the main properties of the material unchanged, and the freeze-dried products produced have a reasonable structure to facilitate water sublimation.
3. Product sublimation drying
The sublimation process before the frozen ice of the product disappears is called sublimation drying. At this time, pay attention to providing a suitable heat flux to ensure that the sublimation proceeds without reaching the eutectic point. If the temperature is too low, the sublimation time is too long. If the temperature is higher than the eutectic point, the product volume will be reduced, and the bubbles will be difficult to dissolve.