Freeze drying is a process of removing moisture from food items without affecting its taste and nutritional content. It is achieved by freezing the product at a low temperature and then removing the moisture through sublimation. The process development technology of fruit and vegetable freeze dryer generally involves the following steps:
1. Selection of raw materials: The selection of raw materials is crucial in the freeze-drying process. High-quality fruits and vegetables that are free from any kind of damage or deterioration should be selected for the process.
2. Washing and preparation: The fruits and vegetables are washed and prepared by peeling, slicing, or chopping into small pieces. Some fruits may require blanching before the freezing process to prevent discoloration and texture changes.
3. Freezing: The prepared fruits and vegetables are frozen at a temperature below -40°C to -50°C for several hours until the product is solid. The freezing process creates crystals inside the product that will later be sublimated.
4. Sublimation: The frozen fruits and vegetables are then placed in the freeze dryer where they undergo sublimation. Sublimation is the process of converting solid ice into water vapor without becoming a liquid. This process is achieved by applying a vacuum to the freeze-drying chamber, which reduces the pressure and temperature allowing the ice to evaporate without melting.
5. Packaging: Once the freeze-drying process is complete, the dried fruits and vegetables are packaged in an airtight container to protect them from moisture and air.
