The utilization of a vacuum during the processing of various food products is one of the healthiest and most prevalent modern methods that have become widespread in various areas of food production including for the production of crunchy fruit and vegetable chips.
Vacuum, characterized by pressure below atmospheric pressure, provides a significant advantage by enabling the processing of products at much lower temperatures. For instance, it efficiently facilitates the evaporation of a solvent from a solution under deep vacuum conditions. Its versatility is further demonstrated as it can seamlessly integrate multiple processes such as evaporation, drying, and cooling into a single installation.
In a deep vacuum, the boiling point of water is significantly reduced, causing water within the hot product to begin boiling when it enters a rarefied medium. The relationship between the vacuum depth and boiling point is directly interrelate. The higher the vacuum, the lower the boiling point of the products. For instance, at 50 mBar, the boiling point of water decreases to approximately 32 degrees.
The benefits drying under vacuum conditions include:
- Swift product drying
- Expedited product cooling
- Safe and secure processing method
- Economically efficient
- Ability to process heat-sensitive products (drying, concentration)
- Efficient removal of solutions from large surface areas
- Preservation of nutrients and organoleptic properties of the initial product
- And much more!
These advantages are crucial for drying fruits, vegetables, and various plants and herbs used for medical and medicinal purposes, as well as in the production of food supplements from natural raw materials.
As a standard practice, vacuum drying is carried out by using cabinet-type batch dryers. These dryers come in various types, each depending on the heat source:
- Microwave
- Infrared
- «Warm shelf», relying on heat transfer through the shelves equipped with “jackets”
Typically, the chambers of these dryers consist of robust containers made out of thick stainless steel, capable of withstanding deep vacuum conditions. Inside these chambers, shelves are installed for the positioning of the product. Such dryers are equipped with a built-in heating system (depending on the type of heat generator), a vapor removal and condensation system, a vacuum system, and a cooling system featuring a cooling machine essential for the proper functioning of the condenser. Additionally, a condensate collection tank is included. These units usually offer the flexibility to adjust the temperature, vacuum depth, and run time.
