Vacuum drying
The use of vacuum in the processing of various materials is one of the modern methods that have become widespread in various areas of production.
Vacuum is a pressure below atmospheric pressure, the main advantage of which is the ability to process products at low temperatures. Like, for example, evaporating a solvent from a solution under high vacuum. It is essentially several processes in one: evaporation, drying and cooling.
In a deep vacuum, the boiling point of water is significantly reduced, so that the water contained in a hot product, for example, begins to boil already when it enters a rarefied medium. There is a direct relationship between vacuum depth and boiling point. The higher the vacuum, the lower the boiling point of the products. For example, at 50 mBar, the boiling point of water is about 32 degrees.
The advantages of vacuum drying processing:
- quick drying of the product
- rapid cooling of the product
- safe way of processing
- economy of processing
- heat-sensitive products can be processed (dried, concentrated)
- allows you to remove the solution from a large surface area
- preservation of nutrients and organoleptic properties of the original product
And much more!
All these advantages are important and necessary for drying fruits, vegetables and other various fruits that are used for medical, medicinal purposes. In the production of food supplements from natural raw materials.
As a rule, vacuum drying is carried out in cabinet-type batch dryers.
There are several types of such dryers, depending on the heat generator:
- microwave
- infrared
- “warm shelf”, which is based on the transfer of heat through the “jackets” that the shelves are equipped with.
Typically, the chambers of such dryers are tanks made of thick stainless steel, which is able to withstand deep vacuum. Inside, shelves are installed on which the product is laid out. Such dryers have a built-in heating system (depending on the type of generator), a vapor removal and condensation system, a vacuum system and a cooling system with a refrigeration machine necessary for the correct operation of the condenser, and a condensate collection tank. The units usually have the ability to adjust the temperature, vacuum depth and run time.