the preparation of the product takes place in the following stages:
Pre-treatment (Optional):
• Washing and Sanitizing:
This step is often used for food items like fruits and vegetables to remove dirt, bacteria, and other contaminants.
• Slicing or Dicing:
Products may be cut into smaller pieces to increase surface area and accelerate drying.
The product is rapidly frozen to a very low temperature (typically up to-35°C) specialized freezers. This freezing preserves the product's structure and minimizes ice crystal formation, which can damage the product during drying.
Primary Drying (Sublimation):
The frozen product is placed in a vacuum chamber with low pressure and moderate heat. Under these conditions, the ice sublimates (transitions directly from solid to gas) without melting into liquid water. This process removes most of the water content (usually up to 95-97%).
Secondary Drying (Desorption):
In some cases, a secondary drying stage might be neces-sary to remove any remaining bound water molecules that are more tightly linked to the product. This stage typically involves slightly higher temperatures and lower pressure compared to the primary drying stage.
Once dried, the product is sealed in airtight containers with minimal moisture content to prevent spoilage or rehydration. Freeze-dried products are usually lightweight and have a long shelf life if stored in cool, dark, and dry conditions.